bite my words

Dispelling nutrition myths, ranting, and occasionally, raving


Everything you want to know (and probably more) about vitamin K


No ranting today. No raving either. A little while ago, a friend asked me to write a post about vitamin K-rich foods. So, this post is just straight-up info for those who are interested in learning more about vitamin K.

You may be wondering, “What is vitamin K?” (if you’re not, feel free to skip on ahead to the next paragraph). Vitamin K is a family of compounds including phylloquinone (vitamin K1) which is found in plants, and menaquinones (vitamin K2) which are found in fish oils and meats (thanks old nutrition textbook: Perspectives in Nutrition by Wardlaw and Hampl).

Vitamin K is essential for blood clotting. Fun fact: the Danish researcher who discovered the relationship between vitamin K and blood clotting named it for the word “koagulation” (which, in case you couldn’t guess, translates to “coagulation” in English). The adequate intake for women is 90 mcg a day, for men, 120 mcg, based on typical adult intakes. In addition to food sources of vitamin K, microorganisms in our intestines also produce vitamin K.

Although, vitamin K is a fat soluble vitamin, there is no upper limit set for consumption as it tends to disappear from the body within a few days of consumption. However, high dose supplements are not recommended as the synthetic form of vitamin K is far more potent than the naturally occurring forms as has been found to cause hemolytic anemia in rats and severe jaundice in infants. Vitamin K deficiency is also relatively uncommon. It’s most likely to be seen in people who have fat malabsorption (e.g. celiac disease or some types of bariatric surgery), long-term antibiotic use, or seniors with little consumption of leafy green vegetables. Newborn infants are routinely given vitamin K injections within 6 hours of delivery as they are at risk of defective blood clotting and hemorrhaging as a result of vitamin K deficiency. It’s important for people taking blood thinners, and some other medications, to consume consistent (or limit) amounts of vitamin K containing foods to ensure efficacy of the medications.

As alluded to above, leafy greens are the primary dietary source of vitamin K. Kale tops the list at 530 mcg per 1/2 cup (cooked), followed by turnip greens (520 mcg per cup), spinach (480 mcg/cup), brussels sprouts (150 mcg per 1/2 cup), raw spinach or cooked asparagus (144 mcg/cup), cooked broccoli (110 mcg for 1/2 cup), and looseleaf lettuce (97 mcg/cup). Other good sources of vitamin K include: cooked green beans (48 mcg per 1/2 cup), raw cabbage (42 mcg/cup), sauerkraut (30 mcg per 1/2 cup), green peas (26 mcg per 1/2 cup), soybean oil (25 mcg/tbsp), and cooked cauliflower (20 mcg/cup).


What you need to know about magnesium


Photo “nuts!” by Adam Wyles on Flickr, used under a Creative Commons Licence.

I recently read an article about magnesium that someone shared on facebook. Shockingly, for FB, it wasn’t nearly as inaccurate as I had expected. However, there were a couple of things in it that I wanted to address. The premise of the article was that most of us are magnesium deficient. This is untrue. Most of us don’t consume enough magnesium but there’s a world of difference between that, and being truly deficient. Magnesium deficiency manifests as an irregular heartbeat which may be accompanied by weakness, muscle spasms, disorientation, nausea, vomiting, and seizures. People who are at greatest risk of magnesium deficiency include: users of some diuretics, those with diabetes, people with alcoholism, as well as those who live in climates where they experience frequent heavy perspiration or those who have long bouts of vomiting or diarrhea.

So, how much magnesium should you be consuming? If you’re a man between 19 and 30 years of age, you should be consuming about 400 mg a day. Women in this age group should be consuming about 310 mg a day. Needs increase beyond this age by about 20 mg/d for men and 10 mg/d for women, and for those experiencing the conditions listed above. For more information of magnesium recommendations, click here. According to one of my old nutrition textbooks (Perspectives in Nutrition by Wardlaw and Hampl), assuming things haven’t changed that much in the past eight years, men consume 325 mg, women 225 mg, on average each day.

It’s not that terribly difficult to reach the recommended intakes of magnesium. One cup of spinach contains 157 mg, one cup of squash `105 mg, 1/4 cup of wheat germ 90 mg, 1/2 cup of navy beans 54 mg, 1 cup of plain yoghurt 43 mg… Nuts and seeds are also good sources of magnesium; as is dark chocolate and raw cacao (nibs, powder). Other leafy greens, beans, and legumes are also good sources of magnesium.

If you do decide to take a magnesium supplement, you should be aware that they are not all the same. Magnesium oxide tends to be the most common and inexpensive form of supplemental magnesium. However, it is also the most poorly absorbed form of magnesium. Liquid magnesium supplements will be best absorbed; the quantity of magnesium listed on the label is not as important as the form. As far as tablets and capsules go, Magnesium lactate, magnesium gluconate, and magnesium citrate are the most absorbable. However, magnesium citrate may have laxative effects, and magnesium hydroxide and magnesium sulfate are forms commonly used as laxatives. Zinc supplementation may interfere with magnesium absorption, while vitamin D supplementation may enhance magnesium absorption. Some medications may also affect magnesium absorption. As with any supplement, you should always check with your pharmacist to ensure that there will be no interactions with any other medications you’re taking. As with any nutrient, it’s best to try to get it from your food rather than from a supplement.


Is it unethical for dietitians to sell supplements?


Eggcup of Pills photo by John Twohig on Flickr. Used under a Creative Commons Licence.

Something happened recently that kind of blew my mind. I was always under the impression that it was a conflict of interest for a dietitian to sell supplements. Short of causing someone harm, in my mind, it was pretty much one of the most blatantly wrong things that a dietitian could do. In my mind, it still is, but according to at least one College of Dietitians, it’s not.

I happened to be exploring a fellow dietitian’s website, as I’d seen them make some questionable assertions in blog posts. You know, the sort of sensational “sexy” hype that I’m always saying we RDs don’t make. I happened to notice that they had a “shop” in which you could purchase several supplements. I shared this information with a friend, another dietitian, who passed it along to a contact at the College in their region. The response indicated that this might be a concern; however, if there is scientific backing for the supplements, as long as clients don’t feel pressured into purchasing supplements, while not ideal, it’s kind of okay. What??

One of the main reasons that many mainstream healthcare professionals take an exception to some alternative healthcare professionals is that they peddle supplements to their clients. It shouldn’t matter how much science there is supporting the use of a supplement. For any healthcare professional to receive direct compensation for the sale of a supplement or drug is a clear conflict of interest. No matter how amazing the supplement may be, no matter how questionable the supplement may be, the potential to profit from its sale to a client can cloud the judgement of even the most upstanding healthcare provider.

I can understand the desire to make money by selling things. It can be tough to make a living as a dietitian. A supplement may seem like a fitting choice. However, it undermines our credibility. For one thing, there is little evidence to support the use of most nutritional supplements. Imagine the more extreme scenario: You go to see your doctor who diagnoses you with disease X. Fortunately, there is cure Y which she can sell you. Can you not see the potential for corruption? misdiagnosis? Unnecessary treatment? Incorrect treatment? Despite the best of intentions, this can happen when the person who is assessing your condition is also selling you the cure. It’s unethical for healthcare providers to profit from a direct sale of a treatment.

If you ever visit a healthcare professional who offers to sell you a treatment or cure, please report them to their governing body. Get a second opinion. Do some research. We need you to ensure that all healthcare professionals are doing their utmost to ethically optimize your health.


Supplements: Should I take truBrain drinks?

I guess promoted tweets do come in handy every now and again. Blog fodder. This tweet appeared in my feed last week:


Naturally, my response was: that sounds like complete and utter bullshit.

I went to their website to look for the science to back-up their claims; i.e. an increase in productivity. Naturally, the truBrain research team conducted the study. Surely no bias there. The study itself? Seven. Yep, seven, participants were examined for changes in EEG results following one week of truBrain consumption. The EEG was used to measure brain activity. There was no control group and no blinding (read: high likelihood of bias). Even with the deck so well stacked in their favour, the “researchers” found no significant results at a group level. This pilot study is the only research cited on their website.

Okay, so there’s no real science to support the claim that truBrain can increase productivity. Perhaps a look at the ingredients can provide more illumination:

375 mg of CDP-Choline – The lovely folks at indicate that there is some minor evidence to support the use of CDP-Choline to support memory and attention, and decreased cognitive decline in older adults. If there is a benefit conferred by CDP-Choline, this might be an effective dose.

200 mg of DHA – This is an omega-3 fatty acid. There may be benefits seen at this dose, although there is no scientific consensus. Also, benefits are most likely seen in individuals who do not regularly consume fatty fish.

375 mg of L-carnitine – This is quite a low dose. While there is some limited research to support the use of L-carnitine to increase cognition in the elderly, there is no research to support its use in the young.

300 mg of L-theanine – This is an amino acid that may promote relaxation. There is no research supporting its use to improve cognition.

375 mg of L-tyrosine – Another amino acid. As a supplement, it may reduce stress and memory in the presence of an acute stressor.

120 mg of magnesium- Many of us don’t consume enough magnesium in our diets so it’s hard for me to knock the inclusion of this mineral in their beverage. However, this is a rather low dose. Some forms of magnesium can cause gastrointestinal distress and diarrhea. It’s also important to note that magnesium supplementation is unlikely to have any effect on cognitive performance.

800 mg of oxiracetam – This is a mild stimulant that may improve memory but there aren’t currently human studies to support this.

In addition to the “medicinal” ingredients, truBrain drinks also contain the following “natural” sweeteners: pomegranate, stevia, blue agave, cranberry, sugar cane, and monk fruit. Six sweeteners. Sweet enough for ya? Not mentioned in any of the ingredient lists is caffeine. The website shows an option for purchasing “non-caffeine drinks” but at the moment they have not yet developed any.

At the low end of the scale you can purchase 15 drinks for a one time fee of $60 or $50 per month. That’s $4 per packet. Unfortunately, the website doesn’t clearly state the size of each drink packet nor the full ingredient list or nutrition information. Without complete information, I can’t completely rip these truBrain supplements to shreds.

Apparently these supplements were developed by neuroscientists. While this might seem to lend an air of believability to their claims, it truly only shows that no profession is exempt from quackery and the desire to turn a profit.


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Throwing the fish out with the oil


For the most part I love Fooducate; however, I was a little surprised by this recent blog post on their site. The post referenced a recently published study that suggested our touting fish oil supplements (or even the recommendation to consume fatty fish twice a week) is faulty. They did not offer any thoughts or critique on the new “study”.

The study was actually an analysis of previously published research. They claimed that our recommendation to consume fish (or fish oil) was based solely on a research study of Icelandic Eskimos conducted in the 1970s. They assert that the findings of this study were misinterpreted and that the researchers did not even look at the prevalence of cardiovascular disease in the population they studied. They then looked at the other research on diet and CVD in Eskimo and Inuit populations. They only found one study that performed direct measurements on the Greenland Eskimo
population for assessing the presence of CAD or CAD risk factors”
. They state that this study, conducted before the Eskimo population had adopted a Western diet, found no difference between incidence of CAD in the Inuit population in comparison to American and European populations. Interestingly, I took a look at the original research study and the researchers actually found a lower risk of CVD in the Inuit population as compared to the Western population. Essentially the opposite of what the current researchers are claiming.

So… “What the heck does this all mean??” you may be wondering. Should you be eating fish twice a week? Should you be taking fish oil supplements? Well, unless you are a Greenlandic Inuit then this research may not apply to you at all. We can’t say that what’s healthy for the Inuit population is healthy for other populations. We also can’t be certain that it’s the consumption of fatty fish that reduced their risk of heart disease. It may be any of  number of other lifestyle factors that placed them at lower risk for CVD. Recent research into the benefits of fish oil has yielded mixed results. Some studies show benefits of fish oil consumption, others show negative effects of its consumption. As always, the best advice is that variety is the spice of life and it’s best to obtain your nutrients from whole foods. Yes, eat fish (limit the larger saltwater fish you consume though as it can be high in mercury), choose a variety. If you don’t eat fish, you might want to consider consuming a fish oil supplement. There may be benefits other than lower CVD risk associated with consuming omega-3s from fish/fish oil (such as mental and cognitive well-being, bone and joint health). Research is ongoing and you might want to wait before you turf your fish oil supplement or grilled salmon.