Why Am I Allowed to Drink Clear Fluids Before Surgery, but Not Eat? (McGill OSS)

5 minute read

Surgeons often instruct patients to refrain from consuming food or drink before surgeries. However, even when patients aren’t allowed to eat, they can often drink “clear fluids”. Why aren’t clear fluids counted as consumption, and what purpose does fasting before surgery even serve?

Read the full article here: https://www.mcgill.ca/oss/article/health-general-science/why-am-i-allowed-drink-clear-fluids-surgery-not-eat

No Need to Shave the World: Why Your Beard Is Not a Problem in the Age of COVID

6 minute read
originally posted here: https://mcgill.ca/oss/article/health/no-need-shave-world-why-your-beard-not-problem-age-covid

In 1843 a letter to the editor entitled “The growth of the beard medically considered” published in the Boston Medical and Surgical Journalargued that beards were medicinally beneficial, and that “the practice of shaving the beard, and thus depriving the face, throat and chest of that efficient protection which nature has provided” was responsible for the “numerous diseases of the respiratory organs with which mankind are afflicted.”

Yet, by 1916 beards had lost their safeguarding status. Edwin F. Bowers (who would go on to invent the pseudoscience of reflexology) wrote in an article for McClure’s Magazine that “there is no way of computing the number of bacteria and noxious germs that may lurk in the Amazonian jungles of a well-whiskered face, but their number must be legion.”

It was only two years later that the 1918 Spanish Flu pandemic hit, and any possible disease vector, including beards, was targeted in bids to quell the number of sick individuals. Given that we’re currently in the midst of what the United Nations is calling “a global health crisis unlike any” it seems inevitable that beards once again fall under the literal microscope as potential germ gardens.

Luckily, given the scientific advances that have taken place since the last few hundred years, we don’t need to rely on racially contentious observations like this one from 1843: “those nations where the hair and beard are worn long, they are more hardy and robust and much less subject to diseases, particularly of a pulmonary character, than those who shave.”

Let’s see what science has to say about how pathogenic your facial hair might be.

Does facial hair collect more germs than a smooth face?

The real question of hair’s cleanliness isn’t whether or not it can harbour microbes. Unfortunately, just like any other surface, it most certainly can. What we really care about is whether a beard contains more germs than a clean-shaven face.

A 1967 study saw four volunteers’ beards or clean-shaven faces sprayed with a bacterial solution and swabs taken from their skin 30 minutes and six hours after, either with or without letting them wash their faces with soap. They found that while there were more bacteria on clean-shaven faces than on beards before washing, more bacteria were removed by washing a clean-shaven face compared to washing a beard. So even though the beards didn’t accumulate more bacteria than the face, they did retain it through the wash.

A 2014 study reinforced the finding that facial hair doesn’t accumulate more bacteria than non-hairy facial skin. Researchers took swabs from the cheeks and upper lips of 199 healthcare workers who had facial hair and 209 who didn’t. The results showed that clean-shaved healthcare workers were actually more likely to harbour certain types of bacteria than their fur-faced coworkers. Similarly, a 2015 study of 118 mustachioed and 123 non-mustachioed men found that “nasal S. aureus [a bacterium] carriage is similar in men with and without a mustache.”

So even though beards may retain bacteria through a wash (highlighting the importance of washing your beard well), there’s no evidence that they accumulate or harbour larger bacterial populations than smooth faces.

Does facial hair spread more germs than a smooth face? 

The other piece of this facial hair puzzle is whether or not people with beards spread more microbes than those without. This question has been at the forefront of a debate over whether or not doctors, nurses, surgeons and other healthcare workers should be allowed to have facial hair. Some people fear that their beards and mustaches could be contaminated and lead to infected patients. Others worry that strict facial hair rules unnecessarily limit a doctor’s personal choices.

Part of why this debate rages on is due to some conflicting study results. A study published in 2000 by McLure et al. compared the bacterial shedding of 10 bearded, 10 clean-shaven and 10 female subjects. The researchers had the volunteers wear a surgical mask either while talking and moving their faces such that the mask “wiggled” around or while still. They held agar plates just below their chins to collect any bacteria that fell off and then cultured these colonies and quantitated them. The results showed that with or without mask wiggling, bearded subjects shed more bacteria than clean-shaven ones.

However, a 2016 study by Parry et al. using the same methods found no difference in the amounts of bacteria shed by bearded versus clean-shaven subjects regardless of whether they wore a surgical mask, a surgical mask plus a hood (shown below), or nothing.

Image source: http://www.healio.com/doiresolver?doi=10.3928/01477447-20160301-01

Unfortunately, this leaves us at the familiar scientific dead-end: more research is needed. Without another study, preferably one with a much larger sample size than the 30 and 20 of these trials, it’s difficult to know which results to trust. Both researchers present reasonable explanations for their results. McLure et al. suggest that beards “may act as a reservoir for bacteria and dead organic material which can be easily dislodged with movement of the face mask,” whereas the daily act of shaving helps to remove the “superficial layer of skin containing bacteria” and thus give clean-shaven men fewer microbes to shed.

On the other hand, Parry et al. suggest that daily shaving can cause micro-cuts on the face that can serve as hiding places for bacteria. They also pondered if their results could be due to beard lengths. They showed that longer beards shed less than shorter beards when the subjects wore masks and hoods, which they hypothesize is due to longer beard hair being less abrasive and therefore leading to fewer shed bacteria. Unfortunately, since McLure did not report their participants’ beard lengths, it’s not possible to know for sure.

But wait, what about viruses?

To throw another wrench in the interpretation of these results, allow me to point out that all these studies measured the amounts of bacteria on participants’ faces or beards. However, the current COVID-19 pandemic is being caused by a virus, not a bacterium. While this distinction may not seem important, there are a lot of differences between these two types of microbes: in particular, size! As you can see below, the size range for bacteria is roughly 500-5000 nanometres, but for viruses is only roughly 100-800 nanometres, making them quite a bit smaller. The SARS-CoV-2 virus (at the time known as 2019-nCoV) has been reported to be 60-140 nm in diameter, making it a particularly small virus, as viruses go.

Image source: https://www.researchgate.net/figure/Relative-sizes-of-major-host-cells-and-their-components-versus-those-of-bacteria-and_fig4_325937574

In the end, there’s no compelling evidence that beards foster bacteria, but we cannot really say if they do lead to increased bacterial shedding. And as far as viruses are concerned, we have no evidence at all.

The good news is, that if you’re practicing proper social distancing, washing your hands often and not exposing yourself to others unnecessarily, you and your beard are unlikely to encounter the SARS-CoV-2 virus at all. So, if you’re doing your part to flatten the curve by staying home, keeping your beard should be fine. However, healthcare workers should consider the role that their facial hair may play in transmitting microbes and take care to wash it very thoroughly whenever possible. However, I do expect that, given that many facial hairstyles can interfere with special masks called respirators, many have already done a spring shave.

Image source: https://www.cdc.gov/niosh/npptl/pdfs/FacialHairWmask11282017-508.pdf

Static Shocks Are a Seasonal Occurrence, but Science Can Help Us Avoid Them

5 minute read
Originally posted here: https://mcgill.ca/oss/article/environment-general-science/how-can-i-stop-getting-static-shocks

If you live in Canada, you know what a nightmare winter can be for your hair. No, not because of hat hair, (or at least not entirely because of hat hair), but because of static electricity! All those big scarves and wool hats really do a number on the frizziness of our hair. But even if you’re bald you’ve probably noticed that the number of times you get shocked when reaching for everyday items, like keys, doorknobs and shopping carts, increases in the winter too. There’s some interesting science behind these seasonal shocking scenes, and how you can stop them. 

The number one factor influencing how many zaps you get is humidity. But to understand why we need to review a bit about electricity.  When two objects made of different materials come in contact with each other, like your hair and a hat, for example, electrons can transfer between them. The more prolonged contact, the more electrons move, creating an imbalance of charges between your hair and the hat.

Whether the electrons move from your hair to the hat, or vice-versa, depends on something called the triboelectric series. It’s basically a ranking of different materials based on their tendency to lose or gain electrons. Some things, like rubber or acrylic, are very likely to gain electrons and become negatively charged. Whereas other things, like hair, glass or wool, are more likely to lose electrons and become positively charged. In the case of your hair and a wool hat, since human hair is higher on the triboelectric series, the electrons flow from your hair to the toque.

The problem is that same charges repel each other, so now that your hair is full of positive charge, it’s rather unstable. That’s why, when you get near something conductive, like a metal doorknob, electrons from the knob will “jump” to your hair to neutralize the charge, shocking you in the process. It’s also why your hair stands on end when statically charged. The strands are repelling each other!

Why do charges build up in our hair or clothes, but not in other materials? Because insulating materials, like plastic, fabric or glass, will hold charges quite well, while conducting materials, like metals, will not.

Water happens to be an excellent conductor, so in the spring, summer and fall, when the air in Canada holds a lot of moisture, any negative charges built up on your body can jump to the air (or from the air to your body, either way results in a shock) whenever they want. We don’t even notice these numerous small jumps. But in the winter the air is drier, so the charges simply sit on your skin, waiting for you to approach another conductor (like your car or your girlfriend) to leap to freedom.

Read this to hear about why winter air, especially indoors, is so dry!

When thinking of how wet or dry the air is, we tend to only consider humidity. But there’s another metric that’s important: dew point. The dew point is the temperature at which the air is totally saturated with water. When temperatures fall below the dew point, water condenses on solid surfaces, forming dew in the summer, or frost in the winter (hence why the dew point can also be called the frost point). Warmer air can hold more moisture, meaning that when temperatures are low, the dew point and the actual temperature are quite close. Conversely, when temperatures are high, the dew point and actual temperature are far apart.

Why does dew point matter? Because temperature, dew point, and relative humidity (that % you see on your weather app) are closely linked.

As an example, as I’m writing this, the temperature outside is -9 ˚C, and the relative humidity is 57%. Using the chart below, or less confusingly, this online calculator, we can find that the dew point is -16 ˚C. This tells us that if we go outside it won’t feel muggy because the temperature is significantly above the dew point and the air isn’t saturated with water.

However, our furnaces bring that air into our homes and heat it. This doesn’t change the dew point, but it does change the temperature and the relative humidity. What was a relative humidity of 57% at -16 ˚C becomes a relative humidity of only 7% at 20 ˚C. That’s some really dry air.

Now importantly, the only thing changing here is the relative humidity. The absolute humidity is the same since the furnace doesn’t add or remove any moisture when it heats the air. So even though the air inside and outside is equally dry, it feels much dryer inside due to the relative nature of relative humidity. 

Source: https://www.ncbi.nlm.nih.gov/books/NBK143947/

One of the easiest ways to counteract the shocks that come with these Saharan conditions is to run a humidifier. Increasing the relative humidity of your home will allow more charges to dissipate into the air and avoid the shocks that come with letting them build up.  Side note: If you think desert-like is a bit too harsh to describe the indoor conditions in the Canadian winter, think again. The average relative humidity of the Mojave Desert is 28%, a full 21% higher than my house right now. No wonder I have chapped lips. 

If a humidifier isn’t cutting it for you, you could also try swapping out your rubber-soled slippers for ones with leather soles. Since leather is a better conductor than rubber, this will prevent charges from building up to the same degree. Similarly, try to surround yourself with more cotton. As it falls in the middle of the triboelectric series, it doesn’t have much of a tendency to gain or lose electrons, so won’t build charges like wool or fur.  

Still really worried about static shocks? You could always purposefully discharge yourself every once in a while. If you carry a metal object like a coin, key or paper clip around with you, and touch it to something metal in your house, any electrons stuck to your body will flow through the metal and away, preventing the “jumping” effect that causes a shock. 

Last, but not least, you can always rely on anti-static products to take the charge out of your hair and clothes. Dryer sheets contain chemicals like dipalmitoylethyl hydroxyethylmonium methosulfate that release positively charged ions when heated to neutralize the negatively charged electrons on your clothes. You can even rub your hair gently with one to remove static! Anti-static sprays and anti-static guns can also be used to keep static to a minimum wherever you need to, from your favourite dress to your Rubber Soul vinyl. 

Source: http://www.saapedia.org/en/saa/?type=detail&id=4070

Is Algaecal a Marine Mineral Miracle or Just Another Overhyped Health Product?

7 minute read
Originally posted here: https://mcgill.ca/oss/article/health-you-asked/algaecal-marine-mineral-miracle-or-just-another-overhyped-health-product-2

Every supplement makes flashy claims, but the ones made by AlgaeCal, that it is “the only calcium supplement that increases bone density” is particularly bold. You see, while every other calcium supplement currently on the market can, at best, decrease the rate of loss of bone density, AlgaeCal claims to be able to fully tip the scales in the other direction and make your bones denser with time. So, are the makers of AlgaeCal lying, or is it truly a miracle marine mineral? Does it represent a breakthrough in the way that we treat osteoporosis? Let’s look at the science.

Why do I care how dense my bones are?

Put simply, because bones that are less dense break more easily, and no one likes broken bones.

As we live our day-to-day lives our bones receive micro-damage. To combat this, our bones are in a constant state of remodelling. So constant in fact that up to 10% of our bones may be in the remodelling process at any one time. This remodelling has two main parts: bone resorption, and bone formation. Most of the time these two processes exist in equilibrium, but as we age this equilibrium can shift (for a wide variety of very complicated reasons). The result is osteoporosis. It affects roughly 10% of Canadians aged 40 or older and is characterized by weak and brittle bones that break in situations healthy bones would not, like when bending over to pick something up.

We can put a number on this loss of bone strength by looking at bone mineral (a calcium-containing compound that makes up 70% of the mass of a human bone called carbonated hydroxyapatite) since it is responsible for most of a bone’s strength. The bone mineral density (BMD) is a good predictor of fracture risks and can be easily and painlessly measured using a DEXA test.

As aside: What is a DEXA test?
DEXA stands for dual-energy X-ray absorptiometry, a non-invasive procedure that involves lying on a table for several minutes while two X-ray beams are aimed at your hip, spine, wrist or other bone. As for how this allows doctors to measure your BMD, I’ll let Osteoporosis Canada explain: “Think of the light shining through the curtains of your home on a sunny day. The amount of light that reaches your eye depends on the thickness of the curtains. If your curtains are very thick, very little sunlight passes through them. If, however, you replace them with a thinner fabric, the light coming through to you will increase substantially. Similarly, a bone densitometer uses a detector to measure the transmission of small amounts of X-rays (light) through your bones. The amount of light that passes through the bone is measured, thus providing a radiologist with a picture that indicates how dense (thick or thin) your bones are.”

How well do the existing calcium supplements work?

AlgaeCal costs more than 100 times as much as normal calcium supplements, so it must work much, much better right? Well, to answer that we first have to look at how well traditional calcium supplements work.

A 2007 meta-analysis published in The Lancet found, looked at both studies using fractures or BMD as their endpoint, and found that calcium supplementation was associated with a 12% risk reduction in all fracture types, and a 0.54% reduction in the rate of BMD loss in the hip and a 1.19% in the spine.

Basically, calcium supplements can help mitigate the decrease in BMD and increase in fracture risk that come with osteoporosis.

An aside: Why do we sometimes use fractures and sometimes use bone mineral density as our outcome?
The main negative outcome of osteoporosis is bone fractures. So, when we’re testing treatments for osteoporosis, we would ideally use fractures as our endpoint. Basically, that means that we would test if patients receiving a particular treatment suffer fewer fractures to see if that treatment works. This, however, can be difficult to do. If researchers run studies on osteoporosis treatments only lasting a few years, they may get artificially skewed numbers, as patients could experience no fractures during the study, but suffer one days after it ends, or they could experience two fractures during the study period but never another. Hypothetically, researchers could monitor osteoporotic patients from the time they’re diagnosed with osteoporosis to the time of their death, but the logistics of funding and operating an over-30-year-long study would be monumental. So, our options are to either run studies over only a few years using fractures as an endpoint but with a large number of participants to help account for the inconsistencies or to use bone mineral density as a surrogate clinical endpoint.

While some studies have found that calcium supplementation is not effective unless given with vitamin D, the Lancet meta-analysis found no statistical difference between the risk reductions offered by calcium alone versus calcium + vitamin D. Vitamin D only affected the fracture risk if the patient was deficient in it, and a similar effect was seen with calcium. Essentially, if you’re vitamin D or calcium deficient, it could be affecting your body’s ability to create new bones, but if you’re not, taking a vitamin D supplement likely won’t help you avoid broken bones, and taking calcium supplements will only help a bit.

How is AlgaeCal different from traditional calcium supplements?

What is it about AlgaeCal that allows it to do what other calcium supplements cannot? Well, what is AlgaeCal?

As you may have gathered from the name, AlgaeCal is made from algae. Specifically, a red algae found in the waters near Brazil, South Africa and New South Wales in Australia. The AlgaeCal website explains that the balls of algae are harvested by hand, sun-dried and then milled into a powder. It states that it is “pure whole food,” even though it is very literally not whole but ground up and that AlgaeCal contains “Nutrients. Not Chemicals.” I hate to be the one to tell them, but calcium, the selling point of their supplement, is so much of a chemical that it’s even on the periodic table of the elements!

The website states that AlgaeCal Plus naturally contains “all 13 essential bone supporting minerals: calcium, magnesium, boron, copper, manganese, silicon, nickel, selenium, strontium, phosphorus, potassium, vanadium, and zinc”, as well as vitamins D3 and K2. Unfortunately, they only provide values for six of these minerals, making it impossible to know if the others are present in useful amounts.

Even for the minerals we know the amounts of, the research supporting their effects on BMD is a bit weak. This 2008 study found no relation between boron intake and BMD in the femur or lower spine, and this 2000 studyfound that low vitamin K2 intake was not associated with low BMD.

So, if these minerals don’t matter, is the calcium in AlgaeCal somehow different than traditional calcium supplements?

Well, it claims to contain “pre-digested” or “plant-digested” calcium. Unsure what this meant, even having studied science for many years, I reached out to the company and asked. Unfortunately, their answer didn’t really explain much: “In regards to pre-digested, the algae itself absorbs all 13 bone-building minerals and pre-digests them for you.” I guess what they mean by pre-digested is just one of the great mysteries of the universe, like dark matter and why it’s impossible to eat only one potato chip.

Anyways, whatever pre-digested means, all that really matters is the bioavailability of the calcium or the amount that is absorbed through your digestive tract and into your bloodstream.

Calcium in conventional calcium supplements (or “rock-based” calcium, as AlgaeCal calls it) can be in a variety of salts, which, according to a 2000 review have bioavailabilities ranging from 23-37%. So, this is the number to beat for AlgaeCal.

Too bad we have no idea what the bioavailability of AlgaeCal actually is! While a clinical trial to answer that question was started in 2009 and finished in 2010, no data from it was ever published. Perhaps because it didn’t show the results that AlgaeCal wanted it to.

Nonetheless, the AlgaeCal website claims that there are 4 studies that support their product’s effectiveness. So, let’s take a look at those.

The studies of AlgaeCal

The first one published looked at AlgaeCal’s effects on human bone cells. The researchers treated human osteoblast cells with either AlgaeCal, calcium carbonate or calcium citrate, and found that AlgaeCal-treated cells showed statistically better function than the cells treated with the other calcium compounds. But there are two problems with this study. First, results in Petri dishes rarely translate directly to humans. Second, this study was funded, at least in part, by AlgaeCal. A conflict of interest that throws all of these results into question.

The next two studies (12), both done in 2011, were thankfully done in humans. They compared several “bone-health plans” (see image below) implemented in 176 participants and found that any of the plans were associated with increases in BMD. Not just that they slowed losses but that they increased bone mineral density!

Unfortunately, a few aspects of the designs of these studies prevent us from trusting their results. They weren’t blinded in any fashion, which means the results could be extremely biased, and they were not placebo-controlled. Oh, and also the lead scientist, Dr. Gilbert Kaats, is the CEO of Integrative Health Technologies inc., a company that has invested in AlgaeCal, and funded one of the studies! That’s a conflict of interest if I’ve ever seen one.

The last study on their site, from 2016, is also headed by Dr. Kaats, and funded via a grant provided by AlgaeCal themselves. Like the others, it wasn’t placebo-controlled or blinded in any fashion and, like the others, it showed increases of BMD over a 7-year period.

If we could trust these results, that is to say, if these results were replicated in a double-blind, placebo-controlled study that wasn’t funded by AlgaeCal or led by someone with a conflict of interest, it would be incredible. If we truly could increase the BMD of those with osteoporosis, not just slow their losses, it would literally revolutionize how doctors treat these patients. But when something seems too good to be true, it usually is.

It’s certainly true that new drugs or treatments are sometimes discovered that revolutionize medicine. A quick look at ganciclovir or penicillin proves that. But it doesn’t happen often, and before we start considering AlgaeCal revolutionary, we need an independently performed study.

So, while we don’t know if AlgaeCal is a pseudoscientific product, it sure does market itself like one. Ever since I first googled this product, I have been inundated with ads for AlgaeCal on every platform from Twitter to Buzzfeed. Now, aggressive marketing doesn’t necessarily mean a product isn’t evidence-based. However, when I’ve previously looked into the science behind products that forcefully target me with ads (like BioSilAllerpet or Skinny Magic) the evidence has not been in their favour.

As of right now, it’s hard to say whether AlgaeCal works or not. All we can really say is that there’s no good evidence that it does. Also, it’s expensive. At $2.17 CAD per day, you would save quite a bit of money by instead buying a traditional calcium supplement and throw in a vitamin D supplement too, for $0.14 per day.

So Your Kid is Trans and You Have Questions (SciMoms)

12 minute read
Originally posted here: https://scimoms.com/so-your-kid-is-trans-and-you-have-questions/?fbclid=IwAR0mJ87CcS9HY0eDiTWq7BC1m3f1hFxGqT9uS0IQdeWj2YeI7-72Y0L8KoY

I was overjoyed to get the opportunity to write about this important topic for SciMoms. As a scientist, I’m sick of bigots trying to use biology to justify their hatred. I wanted to create a resource to help parents, children and allies alike, that would help shift the responsibility of explaining their identities off of trans indidividuals. I’m so happy with this piece, and I hope you find it useful!
Read “So Your Kid is Trans and You Have Questions” here!

My Dog Ate Chocolate and He Was Fine, so What’s the Big Deal?

7 minute read
Originally posted here: https://mcgill.ca/oss/article/health/my-dog-ate-chocolate-and-he-was-fine-so-whats-big-deal

If you ask a dog owner what dogs cannot eat, they’ll list some foods like onions, garlic, rhubarb, grapes and chocolate. (As an aside, if they say grains, don’t listen to them.) Dogs’ inability to safely consume chocolate is common knowledge, but thanks to their proclivity for eating anything they can get their mouths on, many dogs are nonetheless treated for ingesting chocolate every year.

However, there are also many, many dogs who eat chocolate (with or without their owner’s knowledge) who are perfectly fine, no treatment necessary. If chocolate is so bad for dogs, why are these candy-consuming canines fine?

Because, as with all things, the dose makes the poison.

The components of chocolate that are toxic to dogs are theobromine and caffeine. These two chemicals are, structurally, almost identical, and both belong to a group of chemicals called methylxanthines.

Part of what makes methylxanthines so dangerous to animals is how slowly they process them, in particular, theobromine. While dogs reach peak serum (the non-cell part of blood) levels of caffeine after 30-60 minutes and eliminate half of an ingested dose in 4.5 hours, they don’t reach peak serum levels of theobromine until after 10 hours and take 17.5 hours to eliminate half of it.

While they’re in the blood, methylxanthines have a few effects. Primarily, they inhibit the activation of adenosine receptors. These receptors are generally responsible for making us feel sleepy, and decreasing the activity of our bodies. Methylxanthines inhibit these sleepy feelings and act as stimulants.

An aside: Grapefruit’s effects on theobromine metabolism

The enzyme responsible for metabolizing theobromine is a member of the cytochrome P450 family. If you’ve heard of these enzymes its likely because you take a medication that is similarly affected by them (such as Viagra, Cialis, Erythromycin, Xanax and many others) and you’ve been warned to stay away from grapefruit juice. This is due to compounds in grapefruit interfering with the P450 enzymes. Without properly functioning enzymes, medications aren’t broken down as they should be, and overdoses can occur. These compounds aren’t exclusive to grapefruits: they’re also found in pomelos, bitter oranges and Seville oranges that are used to make marmalade. Luckily dogs don’t often consume the fruits that harbour these compounds, however, if Marmaduke ever eats a jar of marmalade as well as some chocolate, he would be in serious trouble. 

So, what does this mean for your dog who ate a chocolate bar? It means they will feel nauseous and probably vomit, they’ll have a high heart rate, diarrhea, show signs of hyperactivity and, if they consumed a high dose of methylxanthines, tremors, seizures and possibly death.

What exactly is a high dose of methylxanthines however depends on your dog.

According to the ASPCA mild effects of theobromine poisoning can be seen at a dose of 20 mg/kg. Severe signs begin at about 40 mg/kg and seizures can begin at 60 mg/kg. A median lethal dose (LD50) is the dose of a toxin required to kill half of a sample population. It’s a common way of measuring a lethal dose of a substance in toxicological research, and for theobromine, the LD50is 100-200 mg/kg.

Notice that because all of these doses are given per kilogram of dog, what’s a low dose of theobromine for a German Shepard could be an exceptionally large dose for a chihuahua.

To illustrate my point, allow me to introduce three dogs. First, we have Baci, a 5-year-old, 7-kg Maltipoo. She’s considered a small dog by all reasonable metrics.

Next meet Chanelle, a 10-year-old Golden Retriever who is solidly medium-sized at 25 kg.

Last, we have Jupiter, a 5-year-old Malamute/German Shepherd cross who is quite large at 50 kg.

I’ve run some numbers to see how each of these dogs would fair if they ate the same amounts of chocolate. You can see my results in the chart below and can replicate my calculations easily using one of the online chocolate toxicity calculators.

(Green = <20 mg/kg, yellow = 20-40 mg/kg, red = 40-60 mg/kg, black = >60 mg/kg)

So, we can see that while Jupiter will probably be fine if he scarfs down 1/3 cup of cocoa powder (the amount in your average recipe for brownies), Chanelle would likely be sick, and Baci would be facing seizures and possibly death.

It’s easy to see, when you start playing with the numbers, how so many dogs can eat chocolate-containing foods and be totally fine. Chanelle could easily consume ½ cup of chocolate ice cream, or a chocolate pudding cup, or a chocolate cupcake and not even show the slightest sign of being sick!

An aside: What about mulch made from cocoa bean shells?

In recent years cocoa-bean-based mulch has gained popularity as an attractive alternative to traditional mulch. It can be good for your garden, contributing nutrients and preventing weed growth, but it can be really bad for your dog. With up to 32 mg of theobromine per gram, cocoa bean mulch can be a more potent source of theobromine than even pure unsweetened baking chocolate. If you can’t guarantee that a dog won’t munch on your mulch, you’re better off sticking to the traditional mulches, which come with the bonus of being much cheaper! 

Even if your dog doesn’t get sick from eating small amounts of chocolate however, it’s still best that they avoid it. One study found that repeated theobromine exposure led to the development of cardiomyopathy (a chronic disease of the heart muscle that makes it harder for the heart to pump blood) in dogs.

An aside: There may also be a genetic component to dogs’ ability to metabolize theobromine

Dogs with a particular variant in their CYP1A2 gene (the variant is 1117C>T) lack the ability to properly metabolize and break down some substances, including lidocaine, naproxen and theobromine. This has important implications in their veterinary treatment and could explain why some dogs get sick after eating very little chocolate.  

So, what should you do if you suspect your dog has eaten chocolate? You have a few options. You can check an online calculator (like this one) to see if your dog is likely to exhibit symptoms, or call animal poison control (1-888-426-4435 in Canada and the U.S.). Keeping in mind that such resources are not substitutes for veterinarian care, you should monitor your dog closely no matter what they say, looking for symptoms like a fast heart rate, vomiting or tremors.

If your dog ate an unknown amount of chocolate; is exhibiting symptoms; is pregnant (theobromine can cross the placenta and affect the puppy); or has other health complications, you should take them to a vet right away. Symptoms may not develop until up to two hours after ingestion, but veterinarian anti-chocolate treatments are most effective if performed as soon as possible after ingestion.

And what exactly do they do to cure a dog of theobromine poisoning? Gastric decontamination. The first step is to empty the stomach (if the ingestion was recent enough). This is often done with a drug called apomorphine which is administered through the eye so that it is quickly absorbed.

Next a vet will administer activated charcoal, a finely powdered material capable of binding a variety of drugs and chemicals. Activated charcoal is most effective if given immediately after ingestion of the toxin and is usually given by mixing it with wet dog food (beware: it will turn your dog’s poop black). In some cases, repeat administrations of charcoal are necessary, but in others just one dose will do it.

Beyond these steps, a theobromine-poisoned dog will just be given medicines to manage their specific symptoms, such as Diazepam for seizures or hyperexcitability, beta blockers for high heart rate, Atropine for low heart rate or others.

Before you go: a note on cats

As it turns out, cats are actually more susceptible to theobromine poisoning than dogs, but we don’t ever hear about a cat getting sick from eating chocolate. Why is that?

Mainly because cats don’t eat as indiscriminately as dogs. Dogs are known for eating just about anything they can find (including joint butts, a practice that places them at risk for cannabis poisoning), whereas cats tend to be picky eaters. In part this is explained by the fact that cats lack the ability to taste glucose.

If all chocolate tasted like 100% dark chocolate, you likely wouldn’t eat much of it either.

Take-home message:
 • Chocolate is poisonous to dogs mostly because of its theobromine content, which dogs are unable to metabolize effectively. 
 •The amount of chocolate a dog can eat without showing symptoms varies drastically with their weight
 • If your dog eats chocolate, you should monitor them closely and seek veterinary attention if they show any symptoms, or if they are very young, pregnant or have other health concerns.

Special thanks to Rachel Malkani MSc. CDBC and veterinary PhD candidate, and to Henry for inspiring this article by, as you may guess, eating chocolate.

Why Mosquitos Bite You and How to Make Them Stop

Originally posted here: https://mcgill.ca/oss/article/health-technology/why-mosquitos-bite-you-and-how-make-them-stop
15 minute read

Summertime means hammocks, BBQs, fireworks, and mosquito bites.

At least it does for me. Those rotten little suckers seem to just love me. They’ll flock to me even when there are three other people sitting in my backyard. What is it about my blood that they seem to enjoy so much?!

Let’s take a look at the science behind mosquitos and try to answer two questions: Why do mosquitos bite certain people, and what should we do to make them stop?

Take-home message:
– Blood type may or may not play a role in attracting mosquitos
– Products using DEET, icaridin, PMD, metofluthrin, and some blends of essential oils are effective at repelling mosquitos
– Bug zappers, sonic devices, citrosa plants, B vitamins, and scent-baited traps are not effective at repelling mosquitos and should be avoided

Mosquito isn’t a Species, it’s a Group

Before discussing the nitty-gritty of mosquito attraction, we need to realize something. While we tend to think of all flying bugs with proboscises as mosquitos, in truth there are more than 3500 species categorized into 112 genera that fall under the moniker of mosquito.

With such variation in species comes a lot of variation in habitats, behaviours, and risks. For instance, malaria is transmitted to humans only by mosquitos of the genus Anopheles, while yellow and dengue fever are transmitted by those in the genus Aedes. Canada is home to roughly 82 species of mosquitos belonging to the genera Anopheles, Culex, Aedes, Mansonia, and Culiseta. Some mosquitos are anthropophilic, meaning that they preferentially feed on humans, while others are zoophilic and preferentially feed on animals.

We’re typically taught to remove standing water from our property and avoid boggy or marshy areas (good luck in Ontario) to avoid mosquitos, but some species of these bugs don’t exclusively lay their eggs in water. We tend to think of mosquitos being at their worst in the summer, at dusk and dawn, but different species are active at different times, and their behaviour can even change from season to season, making it hard to predict when we are at risk of getting bitten.

Something that is true of all mosquito species though is that only the females bite. They require a blood meal in order to produce their eggs. The nasty by-product of this reproductive cycle is that they transmit diseases, and actually kill more people per year than any other animal.

How Mosquitos Track You

Mosquitos home in on their dinner-to-be by following a few different signals. The first clue that something biteable is nearby is the detection of a COplume exhaled on the breath of mammals and birds alike.

The amount of CO2, however, does not affect the attractiveness of a specific target, so even if you’re a human who produces more COthan others (such as those who are larger or pregnant) that alone is not responsible for your irresistible-to-mosquitos aura. This makes sense since large animals like cows naturally produce much more COthan humans, yet many mosquito species still prefer to bite us.

Mosquitos will track a CO­plume until they encounter host-cues. These first of these clues that a target is close by is usually smells emanating from the skin, which we’ll discuss more in a second. As they get close to the source of a smell, mosquitos will then detect and head towards heat and moisture signals emanating from a body.

Source: https://www.sciencedirect.com/science/article/pii/S096098221500740X

We don’t know whether changes in body temperature affect how attractive you are to a mosquito, but we do know that sweating increases the volatile compounds on your skin that they love, and that anhidrotic people, or those who show decreased sweating, are less attractive to the pests.

The main mosquito-cues that can differ between humans are the olfactory ones. While it’s easy to swap your shampoo and soap for unscented varieties that won’t attract mosquitos like the sweet-scented ones do, a lot of the smells that mosquitos sense are innate to your physiology and sadly are not something that we can really change.

A few of these odorous chemicals include ammonialactic acidsulcatone, and acetone. For many of these compounds, however, higher concentrations don’t equal greater mosquito attraction. Instead, they modulate the attractiveness of other substances. For instance, lactic acid has been shown to increase mosquitos attraction to ammonia and CO2.

While an animal may produce similar-to-human levels of CO2, humans tend to produce more lactic acid than primates or cows. This lactic acid synergistically increases the appeal of CO2for anthropophilic mosquito species, while actively dissuading zoophilic species from landing on you. Conversely, ruminants like cows also exhale1-octen-3-ol, a substance that attracts zoophilic species of mosquitos. In a demonstration of this, skin rubbings taken from cows were made just as attractive to anthropophilic mosquitos as skin rubbings from humans via the addition of lactic acid.

The Role of Blood Type

There has been significant debate over the role blood type plays in attracting mosquitos. Initially, a 1972 study using Anopheles gambiae found that mosquitos preferred those with O type blood (O>B>A>AB). But a 1976 study using the same mosquito species did not confirm this.

1980 study examined 736 patients and found that while those with A type blood made up 17.6% of the control group, they made up 29% of the malaria cases. Conversely, those with type O blood made up 33% of the control group but only 22% of the malaria cases. While this alone does not tell us whether or not certain blood types are more likely to be bitten by mosquitos or contract malaria, it does point to blood type playing some role in mosquito attraction.

Some clarity came with a 2009 study done with Aedes albopictus that found a similar pattern to the original 1972 study: O>B>AB>A. The researchers also compared the mosquito-attracting ability of those who secrete substances corresponding to their blood type onto their skin, versus those who do not. Their theory was that these blood type-specific secretions could explain mosquito’s ability to find their preferred type O prey. Their results, however, showed an order of preference of O secretors>A nonsecretors>B secretors>O nonsecretors>A secretors>AB secretors>B nonsecretors, which do not correspond to the blood type preferences established.

Concerning blood type’s role in attracting mosquitos, we’re stuck with the often-written phrase more research needed. Given the conflicting results and relatively small sample sizes of these studies, we cannot make definitive conclusions. Not to mention that we have no idea how mosquitos are able to detect a target’s blood type from a distance.

If mosquitos do truly target those with type O blood, the authors of this study theorize that preference could have evolved due to the prevalence of type O blood in African nations. The three most populous African nations are Nigeria, Ethiopia, and Egypt, and the percentage of their populations with type O blood are 51.3%, 39.0%, and 52.0% respectively.

How to Avoid Getting Bitten

Anyways, even if we knew what blood types attract mosquitos, you can’t change your blood type. So, what can you do to get some relief from these minuscule menaces?

First, it’s important to remember that just because you’re not forming welts doesn’t mean you’re not getting bit. Not all bites will lead to the familiar welts, so even if you’re not covered in itchy bumps, if you’re near mosquitos you should be using repellant.

Things That Work

Physical barriers should be your first line of defence against mosquito bites. Install screens on your windows, doors, tents, and RVs, and cover children’s cribs, playpens, and strollers with fine mesh to keep mosquitos out.

You can get specialty meshes and clothing treated with permethrin, an insecticide, for adults in Canada. The anti-mosquito effects of the chemical will last through several wash cycles, but permethrin-treated objects should never be used for or around children, including screens or mosquito nets that they may interact with, as their safety has not been evaluated.

In general, you should strive to wear light coloured clothing, and cover as much of your skin as the heat will allow. Mosquitos are better able to orient themselves towards darker targets, so skip the Nirvana t-shirt and try on a white tee instead.

Flowery and fruity scents will attract mosquitos greatly since they feed on flower nectar (in addition to us) but even non-botanical scented products should be avoided whenever possible. This includes (amongst many others): shampoo, soap, conditioner, shaving cream, aftershave, perfume, deodorant, hand cream, makeup, and even laundry soap and softener.

In terms of repellants, the good news is that you have more options on the market than ever. The bad news is that only some of them work.


N,N-Diethyl-meta-toluamide, better known as DEET, has been the standard ingredient in commercial bug sprays since 1957 when it made the jump from military to civilian applications. While it used to be thought that DEET interfered with a mosquito’s ability to detect lactic acid, more recent research has found that mosquitos detect and avoid DEET directly. Much like I do with vinegar.

Misguided fears about DEET’s safety have spurred some to move towards other mosquito repellants, and while there are other effectual repellants, none work as well or for as long as DEET. In terms of its safety, DEET has been more thoroughly studied than any other repellant and when used according to guidelines is quite safe.

When utilizing DEET-based repellants it’s important to pay attention to the concentration of DEET in the product. The Government of Canada recommends that no concentration over 30% be used on anyone and that only formulations containing up to 10% be used on children aged two to twelve (up to three daily applications) and aged 6 months to 2 years (only one daily application). Babies under 6 months should be kept mosquito-bite free through the use of nets and screens rather than repellants of any type.


Icaridin, also known as picaridin, is a safe alternative to DEET popular in Europe and recommended by the Government of Canada for use against mosquitos and ticks on anyone over the age of 6 months. This study showed that products with 9.3% icaridin can repel mosquitos for up to 3 hours, while this study showed that a 10% concentration repelled mosquitos for more than 7 hours. This is comparable to the 5 to 7+ hours of protection provided by 7-15% DEET products, although DEET has been more widely studied. Contrarily this study found a 10% icaridin repellant rather ineffective. If you find them effective, icaridin-based products could be particularly useful for small children who have exceeded their daily recommended applications of DEET-based products but still need to remain outside.


Citronella has long been the standard of backyard BBQs and picnics in its candle form, but in addition to the coils and candles designed to keep mosquitos out of a particular area, there are also repellants that contain citronella oil.

Citronella oil is made mostly from 2 species: C. nardusand C. winterianus, and contains many different chemicals, the most notable in terms of their insect-repelling nature include camphor, eucalyptol, eugenol, linaloolgeraniol and citronellal.

While it’s citronellal that provides the flowers with their characteristic lemony scent, a 2008 study’s findings suggest that it is actually linalool and geraniol that provide the bug-repelling effects. The researchers compared candles made of 5% citronella, linalool, and geraniol, and found the geraniol and linalool candles much more successful at repelling mosquitos than normal citronella (85% and 71% versus 29% repellency rates over 3 hours). This study likewise confirmed straight citronella candle’s inability to effectively repel mosquitos alone.

This study examined three mosquito repellants that contained citronella and found them all significantly less effective than formulas containing DEET or icaridin, and this study examined 3 wearable bracelets that claimed to emit geraniol and found them as effective as using no repellant at all.

So while it could be useful to burn a geraniol or linalool candle while you’re sitting outside, you should probably still backup your protection with an effective repellent.

P-Menthane-3,8-diol (PMD)

Products with p-Menthane-3,8-diol, a chemical found in small amounts in oil extracted from the lemon eucalyptus tree, have generally (studies 1,2,3) show it to be as effective as DEET and icaridin. The Canadian government recognizes PMD’s repellency effects on blackflies and mosquitos but recommends against using PMD-containing products on anyone younger than three.

Soybean and Essential Oils 

Soybean oil is perhaps the strangest bug-repelling ingredient on this list, but repellant formulations containing mixes of soybean oil and various essential oils have been rapidly making their way onto the Canadian market. While the soybean oil itself does not repel mosquitos, it works in tandem with the essential oils also included in the repellants to stabilize their volatility.

This study found that a formulation including soybean oil, coconut oil, geranium, and vanillin repelled mosquitos for more than 7.2 hours. However, the same study, and another, showed that other formulations also containing soybean oil, as well as other various essential oils (menthol, eucalyptus, lavender, rosemary, sage, etc.) worked very minimally.

This points to the particular essential oils and other ingredients in the repellant making the difference rather than the soybean oil itself. This makes sense when you consider that the geranium included in the effective soybean repellant was likely citronella, and that vanillin has been shown to increase the repellency effects of citronella.

The Government of Canada doesn’t place any age restrictions on formulas containing soybean oil but recommends not using essential oil formulations on those younger than 2. So, you’re free to experiment with different products using different ingredient blends and see which works, but make sure to turn to something a bit more reliable when actually venturing into the woods.


If you’d rather wear a clip-on device than use a mosquito repelling lotion or spray, your only good option is those that emit metofluthrin. This 2017 study examined the efficacy of 5 wearable anti-mosquito devices and found that only the metofluthrin at a concentration of 31.2% effectively repelled mosquitos. Much like citronella candles, however, clip-on devices work by creating a fog of mosquito-repelling chemicals around you. This means that they will only be effective for times when you’re sitting still.

Things That Don’t Work

While components of citronella oils may be effective repellants, citrosa houseplants are not. Nor are the sonic mosquito repelling products that claim to play sound at frequencies that will drive mosquitos away. I’ll let the authors of this paper sum up the evidence for these products: “We are not aware of any scientific study showing that mosquitoes can be repelled by sound waves and therefore we consider these devices as the modern equivalent of snake oil”.

While synthetic mosquito lures that attract the bugs just as well, if not better, than humans have been developed, in practice mosquitos continue to be attracted to humans even when these devices are used. Thus, their use is not recommended by the Canadian Government. Likewise, handheld or mounted bug zappers certainly exist and can be quite satisfying to use for revenge on the bugs that stole your blood, relying on them for protection is not a good idea.

You may have heard that eating bananas can alternatively make mosquitos more or less attracted to you. The claims of banana’s repelling power stem from their high vitamin B6 content, but a 2005 study tested the effects of vitamin B consumption on mosquito attraction and found absolutely no effects. In terms of bananas attracting power, those claims come from octenol content, a chemical that does indeed attract mosquitos. But, octenol isn’t unique to bananas, it’s found in many foods, and no studies have been done that prove consuming bananas does make you a bug-target, so keep on munching.

A subtler mistake you may make when selecting your mosquito repellant is to use a product that combines sunscreen and bug spray. While certainly convenient, the problem lies in sunscreen’s need to be reapplied much more frequently than mosquito-repellants. If both products are needed for an outing, it’s recommended that you wait 20 minutes between applying sunblock and repellant.

Basically, to avoid being a mosquito-target you should stay as scent-free as possible, wear light clothes, avoid bogs and use an effective repellent (such as those containing DEET or icaridin). Or, you could always stay inside- I hear its quite nice this time of year.

Kratom- Potential Opioid Saviour?

4 minute read
Originally posted here: https://mcgill.ca/oss/article/health-general-science/kratom-potential-opioid-saviour

Kratom is rapidly becoming a choice recreational drug, but there’s a good chance you’ve never heard of this substance, which can cause sedative effects like morphine at high doses as well as stimulating effects, like caffeine or methamphetamine at low doses. This drug is not new, though regulations concerning it are (at least in North America), and not everyone is pleased about them.

Mitragyna speciosa, commonly known as kratom or ketum, is a tropical evergreen found in Southeast Asia. Its leaves are chewed fresh, or dried, powdered and put into capsules, extracts, slurries or drinks. A user feels the affects about 30 minutes after taking the drug, and they last roughly 6 hours, though the dosage and timings are highly strain dependent. The leaves contain several active compounds, most notably mitragynine and 7-hydroxymitragynine which act as alkaloid opioids. An alkaloid is any molecule that contains nitrogen, and has a biological effect. In these chemicals’ cases, that biological effect is achieved through acting as μ-opioid receptor agonists. These molecules bind to, and activate the opioid specific receptors, much like other opioids such as morphine, codeine or fentanyl. 7-Hydroxymitragynine has a potency equal to 17 times that of morphine, and as well as the molecules mentioned, kratom contains about 25 other alkaloids, each which will affect the body in some way.

Unlike these other opioids however, kratom remains largely unregulated in most of the world. Here in Canada it’s possible to purchase kratom in bulk online, though illegal to advertise it for consumption. While America has had a slightly more complicated relationship to the drug, as of October 2016 the DEA has rescinded its August 2016 move to place mitragynine and 7-hydroxymitragynine on the schedule 1 drug list. Around the world policies vary country to country- unregulated in most African countries, but regulated in Sweden, the UK, Australia and Denmark. Kratom remains entirely illegal in Thailand, where it’s been a controlled substance since 1943. Prior to this regulation, kratom leaves were often chewed fresh to achieve a small stimulation similar to that of coffee.

It’s worth exploring why public outcries to banning kratom have been so fierce, especially when the regulation of other opioids has been met with favourable responses. There is a distinct lack of studies performed on kratom and its effects, and it seems that most studies that were performed conclude by pointing out how it`s too difficult to draw conclusions based on so few studies. The DEA and other law enforcement agencies point to the questionable purity levels of kratom products, the potential for abuse and how leaving drugs unregulated leaves them in reach of young adults. Of concern is the fact that kratom is not detected on standard drug tests, its low cost, its wide availability online, and like any drug, its potential to be cut with dangerous chemicals. Considering the fentanyl crisis currently sweeping BC, a fear of opioids makes sense, but whether the concern is warranted remains to be seen.

While kratom is itself addictive, with even the user guide sites for it instructing users to not take more than 1 or 2 doses a week, there is growing evidence that it could serve as a stepping stone for opioid addicts on the path to getting clean. Studies have shown that kratom may be effective to wean addicts off their opioids of choice. When kratom is fermented, an additional bio-active chemical is produced- mitragynine pseudoindoxyl. This substance has been the subject of much scientific excitement, as it has been shown to be an antagonist for the delta opioid receptor, a process which has been correlated with reduced withdrawal symptoms, and reduced morphine tolerance. The withdrawal symptoms of kratom, which include anxiety, restlessness, tremor, sweating and cravings for the substance, are generally considered to be milder than the withdrawal symptoms of other opioids, though longer lasting.

Studies have shown that tolerance to kratom is not built over time as it is with other opioids. This, combined with its potential to lessen withdrawal symptoms, while still providing the painkiller effects that most patients take opioids for, makes me really look forward to the kratom research that will take place in the near future. It undeniably has potential that warrants study, but at present it is far too soon to start referring addicts to Madam Kratom’s online emporium. The toxicity of kratom has not been properly studied, nor has its interactions with other drugs (legal or otherwise), its long term effects, or even really, its short term effects. While the promise is present the science is not, and it would be truly foolish to rush to the kratom bandwagon without knowing how it will affect most major organs, amongst other things.