Dispelling nutrition myths, ranting, and occasionally, raving


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What you need to know about magnesium

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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.


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Leave the veg for the rabbits, you’re going to die anyway

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A few weeks ago, Dr Sharma shared this article (on twitter and on facebook), without comment. It’s an article by the dreaded Zoe Harcombe about why we shouldn’t be striving for at least five servings a day of fruit and vegetables. No, it’s not what you think. She’s not suggesting that people should have more than 5 servings of veg and fruit a day, she’s suggesting that people should have fewer servings of veg and fruit a day. “Great,” I thought, “Zoe strikes again“.

After working myself up into a bit of a rage about the article I noticed the date on it. January 2011. When I first saw that I thought that I wouldn’t blog about it after all as it’s not current. My second thought was, “whatever”. If I’m only seeing this for the first time there are probably others only seeing it for the first time as well.

Harcombe argues that recent research showing the lack of protection against myriad chronic diseases through increased vegetable and fruit consumption means that we should cease encouraging people to eat more vegetables and fruits. And everyone rejoiced and ate doughnuts for dinner and lived long and healthy lives dying peacefully from old age in their sleep! Dietitians, nutritionists, and other health professionals were suddenly out of work as there was no more chronic disease to contend with. If only.

In the article, Harcombe states, “no doubt some dieticians and nutritionists will reject my arguments. But science backs me up.”
Well, she got the first part of that statement right, at least.

A great deal of Harcombe’s hypothesis centres around the assertion that vegetables and fruit don’t contain many vitamins or minerals. She concedes that vegetables do contain vitamin C and some A and K. Fruit apparently is only good for potassium. According to Harcombe, meat and other animal products are superior sources of most vitamins and minerals. This truly is a load of nonsense. Veg and fruit can be good sources of many vitamins and minerals. Not to mention the fact that they are usually good sources of water and can provide greater volume to your meal with few calories. Food is not just about individual nutrients. It’s about taste and texture and pleasure. Imagine eating a salad without vegetables. Think about the pleasure of eating a fresh blackberry off the brambles. How dull food would become if we didn’t have vegetables and fruit in our diets.

Harcombe moves on from her argument about the lack of vitamins and minerals in vegetables and fruit to say that some dietitians will argue that they are a source of antioxidants. She doesn’t object to this statement but instead says that she would rather not ingest oxidants in the first place. What was it that she said earlier? Oh yeah, “Science backs me up.” Might be time for a review of the oxidizing process, Zoe. If she’s avoiding oxidizing agents I want to know how she’s managed to survive without breathing air or drinking water. Our environment is chockfull of oxidizers. We should certainly avoid adding to them ourselves by avoiding smoking, excessive sun exposure, excessive alcohol consumption, etc. However, avoiding “chemicals” as Harcombe suggests is both ridiculous and impossible. Everything is chemicals. We are chemicals.

There is too much in this article to address it all. I mean, I could, but it’s too nice out as I’m typing this, and would you really keep reading if I went on and on? I just want to touch on one more issue with Harcombe’s vendetta against vegetables and fruit.

Harcombe takes issue with the belief that vegetables and fruit are important sources of fibre in our diets.

“The fact is, we can’t digest fibre. How can something we can’t even digest be so important to us, nutritionally?”

Apparently Harcombe doesn’t mind being constipated. Nor does she recognise the importance of fibre in prevention of heart disease. The desire to feel satisfied after a meal? Also not important. Even if these things are not important to her fibre serves other important organisms inside our bodies. That indigestible fibre is food for the bacteria living in our digestive tracts. Those same bacteria that provide us with things like vitamin B12, protect us against GI upset and harmful micro-organisms. We’ve only just begun to scratch the surface of the importance of our gut bacteria but it seems that they do a lot more for us than we ever realised.

So, if we are to listen to Harcombe and throw those five-a-day away, what are we to eat? Her top five foods: liver, sardines, eggs, sunflower seeds, and dark-green vegetables. That’s right. After telling us that vegetables and fruit are overrated and should be left for the rabbits, Harcombe then turns around and recommends vegetables in her top five foods. I rest my case.


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Why the home test for vitamin quality is crap

 

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I’ve had a number of people mention to me about testing vitamin quality by attempting to dissolve them. While this seems like a good idea, initially, upon further consideration, I can think of a number of flaws with attempting this at home.

The Consumer Lab provides a step-by-step guide to testing the disintegration of vitamins at home. They recommend putting the pill in water warmed to body temperature and then stirring continuously for 30 minutes, maintaining the water temperature. Unless the pill is chewable, enteric coated, or timed-released, it should break down. The implication is, if it doesn’t, it’s not breaking down when you ingest it and your body isn’t getting the nutrients from it. But, there are some problems with this premise.

First, your stomach is a highly acidic environment. Stomach acid usually has a pH of 1.5-3.5. Water, on the other hand, has a pH of about 7 (i.e. neutral). If you wanted to mimic the conditions of the stomach, you would need to use warmed lemon juice, or a similar acid.

Second, creating a warm, acidic environment isn’t enough. Most vitamins are recommended to be consumed with food. During digestion, the stomach releases a whole host of digestive enzymes which work to break down your food, and some of them would likely also have an impact on breaking down any vitamin and mineral supplements. Together the stomach secretions and jumbled-up food forms “chyme” which is generally ready to leave the stomach after 1 to 4 hours. That time-frame gives your vitamin a whole lot longer to break-down than the 30 minute warm water home test does. The stomach also secretes “intrinsic factor” which essential for the absorption of vitamin B-12 (don’t forget to add that to your cup of body temperature lemon juice).

Third, digestion doesn’t end in the stomach. After the chyme moves from the stomach to the small intestine which is actually where most digestion takes place over 3 to 10 hours.

Fourth, as the Consumer Lab test notes, a number of vitamins are designed to take long periods to break-down (i.e. timed-released). Others (i.e. enteric coated) are designed not to break-down until after exiting the acidic environment of the stomach and entering the neutral environment of the small intestine.

Fifth, have you ever shat out an intact vitamin pill? Unless your body’s stashing whole pills somewhere along your digestive tract, it’s probably safe to say that it’s being broken-down along the way.

Sixth, just because a supplement is breaking-down in your body doesn’t necessarily mean that it’s being absorbed. Determining that it dissolves in a cup of warm water won’t tell you if you’re obtaining any nutrients from it.


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Vitamin supplements: deadly or life saving?

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Last week everyone was getting worked up because an editorial in the Annals of Internal Medicine advised against taking vitamin supplements. I wish that I could unequivocally state that they were correct (or incorrect) in this assessment. Unfortunately, this is a complicated issue and I don’t think that we have all of the answers yet.

We know that there are problems with the supplement industry. It’s not well-regulated. Some herbal supplements were recently found to contain ingredients other than those stated on the label, some even contained none of the sole ingredient they claimed to contain. It’s not a stretch to presume that this issue extends to supplements beyond the herbal variety. Last year researchers found that vitamin D supplement often contained hugely variable quantities of vitamin D, even within the same bottle.

An issue unique to multivitamins is that some minerals impede absorption of other minerals when consumed together (for example, zinc and copper). Other vitamins and minerals actually work better together (think calcium, magnesium, and vitamin D). When we’re taking a multivitamin we’re almost certainly not absorbing many of the vitamins and minerals listed on the label (assuming the label is correct in the first place). Does this mean that we should give up on supplements altogether? Possibly not.

The editorial refers to three specific studies. The important thing to note if that these studies looked at people who were not nutrient deficient. The problem with this is that many of us are nutrient deficient. Canadians have difficulty meeting their nutrient needs for calcium, magnesium, and vitamin D through food alone. We also tend to fall short in consumption of potassium as well as EPA and DHA (essential omega-3 fatty acids). There is also the fact that individual nutrient needs vary and that increased nutrients are needed during specific life stages. For example, folic acid is needed early in pregnancy to prevent neural tube defects in infants (1) and many nutrient needs are increased during pregnancy and lactation. Smokers have increased vitamin C needs and athletes have increased needs for nearly everything. Infants require vitamin D supplementation to avoid rickets. Vegans and seniors need vitamin B12 supplements. Etc.

Another problem with the basis on which the authors of the anti-supplement editorial made their recommendation is that they were looking at extremes. They asked: Do multivitamins prevent cancer? Cognitive decline? Heart attacks? Just because vitamin supplements don’t seem to prevent these conditions doesn’t mean that there aren’t other potential benefits to supplementation. More “minor” aliments may be ameliorated by consumption of supplements. We also may have been simply too late to see benefit from supplementation in those involved in those studies. As with osteoporosis which is a pediatric disease with geriatric consequences, these diseases are likely a result of exposures and lifestyles starting in utero.

So, should we take vitamin and mineral supplements or not? I think that it’s a bit of a gamble either way. On one hand you may not be getting what you bargained for in a supplement. On the other hand, you might be risking nutrient deficiency by avoiding all supplements.

Obviously it’s best to try to meet your nutrient needs through food. Realistically, most of us do not do this. If you’re able to determine what specific nutrients you’re lacking in your diet then it’s best to supplement with only those nutrients. Try to select supplements that have an NHP number on them to ensure a minimal level of regulation. And, of course, too much of anything can be a bad thing. Unless advised by your MD or nurse practitioner to take a high dose (and even then, you might want to question them) of any supplement avoid reaching or surpassing the upper limit.


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The latest superfood: Beer

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I saw the tweet (above) yesterday. While it may be true that beer contains all 13 essential minerals (I say “may” because the nutrient profile only lists 11 minerals) I still think that this tweet is misleading. Oh sure, it’s all fun and games, until someone loses a liver. I enjoy a good beer as much as the next person, but I hate to think that anyone would believe that they can obtain all the nutrition that they need from beer.

Let’s assume that the two minerals not listed in the nutrient profile are indeed present in beer. There is certainly not enough of each of these minerals (some are present in extremely small quantities) to meet your daily requirements. For example, a female between the ages of 19 and 51 needs 18 mg of iron a day. One bottle of beer provides 0.7 mg of iron. That’s about 3.8% of the recommended intake for iron. Just for fun, that would mean drinking nearly 26 bottles of beer to meet your daily requirement.

The tweet also neglects to mention that there are other substances required for human life; such as, vitamins and macronutrients (carbohydrate, fat, and protein). Beer is lacking in all of these areas, aside from carbohydrate. Most of beers calories come from alcohol, which, unsurprisingly, is not an essential nutrient.

Another factor to consider: alcoholics tend to be one of the highest risk groups for nutrient deficiency (in the Western world). This is due to lack of consumption of nutrients from food, a need for more nutrients to repair the damage caused by excessive alcohol consumption, and impairment of digestion caused by alcohol consumption.