Dispelling nutrition myths, ranting, and occasionally, raving

The harm in fad diets

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Many of us roll our eyes when we hear about people on fad diets. I think that most of us think, “oh well, it’s not doing them any harm. Let it run its course”. But what if these diets are doing people harm?  I’m not about fear mongering, you know this. Many of these trendy diets can be safe and healthy when followed properly. However, what about when they’re not? There is reasonable risk of deficiencies that could cause some degree of harm at worst, and at best prevent the adherents from attaining optimal health.

What’s the harm in a low-carb or gluten-free or paleo diet?

I’m lumping these two in together even though they’re not strictly the same, although it seems that they frequently go hand-in-hand. Here the risk lies in B vitamin deficiency. Yes, many B vitamins are available from animal foods. However, folic acid (which I blogged about a few weeks ago) was added to refined flour and cereals as a public health measure to prevent neural tube defects during pregnancy in 1998 (1). Eliminating grains from the diet may lead to increased risk of spina bifida, and other neural tube defects, in infants of mothers following these diets. It’s recommended that all women of childbearing age take a multivitamin containing 400 mcg of folic acid daily. Women who are following the above diets should be sure to follow this recommendation. The crucial window for neural tube formation is within the first 21-28 days of pregnancy. This means that if you wait to start taking a prenatal multivitamin once you find out you’re pregnant you may have already missed this window.

What’s the harm in a vegan diet?

While touted as one of the healthiest diets, a vegan diet can easily be deficient in essential nutrients. As with the low-carb diets above, a vegan diet may be low in some B vitamins. In this case, vitamin B12 is more likely to be the B vitamin of concern than is folic acid.

Vitamin B12 is important for many reasons. We need B12 for blood cell formation, nerve function, and brain function.

Vitamin D is also a concern in vegan diets as it’s primarily found in milk, fish, and eggs. During the winter months it’s difficult for most of us, vegans and non-vegans alike, to get enough vitamin D from food alone.

What’s the harm in a low-sodium diet?

This isn’t even so much a risk of low-sodium diet but of a diet that eschews table salt in particular. Now that sea salt is the salt selection of foodies and many of us are avoiding salt shakers there is potential for insufficient iodine consumption. Table salt is fortified with iodine, sea salt is not.

Iodine deficiency during pregnancy can result in poor mental development. Iodine is important in thyroid function and deficiency may result in the development of a goiter.

Now, to be fair, when consideration of balance, variety, and nutrients is taken into consideration all of these diets may be healthy. I think that it’s also worth mentioning that the average Western diet is probably less nutritious than all of the above diets. Most people consume too few vegetables and fruits, too much sodium, sugar, and fat. Most of us, even those of us consuming relatively healthy diets, don’t get enough potassium, vitamin D, magnesium, and fibre. While the focus should definitely be on whole food, it’s worth considering what nutrients your diet may be low in and making an effort to consume more foods rich in those nutrients or even considering taking a supplement if you’re finding it hard to meet your nutrient needs through food alone.

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Author: Diana

I'm a registered dietitian from Nova Scotia, living and working in Ontario, Canada. My goal is to help people relearn how to have a healthy relationship with food.

7 thoughts on “The harm in fad diets

  1. Veganism isn’t a fad diet, it’s not a diet at all – it’s a lifestyle that means you choose to do the least harm to animals by not eating, wearing, or using animal products. Maybe you’re thinking of a plant-based diet?

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    • It all depends on how you approach it. All or none of these diets can be fads or lifestyle changes.

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    • While many people are indeed committed to veganism as a lifestyle, lots and lots of people really do go vegan because it’s hip, or as a weight loss measure, for a week or two. In that case it’s exactly a fad diet. And of course it is harmful when someone randomly decides they’re vegan without learning (or knowing beforehand) anything about nutrition and start eating 2 green salads a day.

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  2. Pingback: Dietitians Week 2015 - Round UP - Food & Nonsense

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