October is Vegetarian Awareness Month! While we are by no means strict vegetarians, we consider ourselves frequent vegetarians and lovers of plant-based meals. But many people are concerned about foregoing meat given cautionary tales that vegetarian diets are “dangerous” and studies indicating their benefits are “myths”.
A recent study published in the Journal of the Academy of Nutrition and Dietetics compared nutrient intakes of over 70,000 individuals across the spectrum of non-vegetarians to vegans (1). How did the vegetarians fare with respect to intake? Are vegetarian diets really that dangerous?
A well-planned vegetarian diet (yes, even a vegan diet!) can be healthy and provide all of the nutrients a person needs*… the emphasis being on the well-planned part of the equation (2). The more foods and food groups excluded, the greater chance for inadequate nutrient intake and deficiencies.
As a part of the Adventist Health Study-2, Rizzo et al. (1) classified vegetarian status into 5 groups:
- Non-vegetarian: frequently consumes meat and other animal products
- Semi vegetarian: consumes meat and fish less than once per week
- Pesco-vegetarian: consumes fish but other meats less than once per month
- Lacto-ovo-vegetarian: no meat or fish, but eggs and milk products
- Strict vegetarian: no animal products (vegan)
Not surprisingly, non-vegetarians had the lowest intakes of plant-based protein, fibre and vitamins and minerals associated with vegetable and fruit intake, such as beta-carotene and magnesium. They also had higher BMIs and the highest intakes of saturated and trans fat, as well as arachidonic acid (an omega-6 associated with increased inflammation) and DHA.
Common nutrients of concerns for vegetarians include: protein, calcium, vitamin D, iron, vitamin B12, zinc and long-chain omega-3 acids (DHA/EPA) (2). It’s important to note that the report by Rizzo et al. (1) is based on total intake – from food AND supplements.
Interestingly, average intake of these nutrients was above minimum recommendations for even the strict vegetarians and only a small proportion of vegetarians had low intakes (1). In fact, total protein did not differ significantly between groups (though source of protein did) – approximately 70+ grams per day – as is comparable to average US intakes (3).
Similarly, calcium and iron intakes were not significantly lower in vegetarians when compared with meat eaters. Of biggest concern for vegetarians in this study, particularly strict vegetarians/vegans, were lower intakes of DHA, vitamin B12 and vitamin D.
Importantly, the Rizzo study focused on Seventh-day Adventist adults 30 years of age and older; thus, their data cannot be extrapolated to children and adolescents. For more information on the benefits and risks of vegetarian diets in a variety of different populations you can check out the Academy of Nutrition and Dietetics (formerly ADA) Position Statement on Vegetarian Diets.
DHA and EPA
Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are long-chain omega-3 fatty acids found in cold water fatty fish, such as salmon, mackerel and sardines. There are currently no *official* daily recommended intakes of DHA and EPA, though the World Health Organization has interim recommendations of 250 mg to 2000 mg of DHA + EPA per day. In a joint recommendations report, the Academy of Nutrition and Dietetics/Dietitians of Canada suggest 500 mg of DHA/EPA each day (4).
While the best way to get your marine omega-3s is by eating fish regularly (click here for food sources), there are some vegetarian sources like fortified milk and orange juice, yogurt, eggs and peanut butter. There are also algae-derived supplements on the market,
if food sources won’t cut it.
When it comes to natural food sources, only nutritional yeast is a non-animal source of vitamin B12 BUT there are fortified options like soy beverage and cereals available.
Although vitamin B12 recommendations are low (2.4 mcg per day for adults) and deficiencies take years to develop, it is a good idea for strict vegetarians to supplement with vitamin B12 (3.) If you eat fish, eggs and/or milk products, your vitamin B12 intake is likely sufficient.
Regardless of whether you are a vegetarian or not, it is very difficult to get enough vitamin D from food alone because there are few natural sources in the diet – fish and egg yolks… and UV-treated mushrooms. Current recommendations for those aged 1 – 70 years is 15 mcg (600 IU) per day… equivalent to 4 oz of salmon or 6 cups of milk.
Fortified sources of vitamin D include milk products, soy beverages, margarine and some cereals. If you live at a northern latitude and wear sunscreen (like you should!), it’s not a bad idea to take vitamin D supplements year-round. You can talk to your doctor about testing your levels and determining what supplement dose is right for you. The upper limit for vitamin D is 100 mcg (4000 IU) per day.
No Baloney’s advice? Vegetarian diets have been linked to a multitude of health benefits, most recently reduced risk of all-cause mortality (5). But eliminating food types and groups requires knowledge and planning to ensure nutritional adequacy. While the Rizzo et al. study findings are not generalizable to ALL vegetarians (Adventists often follow other lifestyle modifications), they do indicate specific nutrients of concern for vegetarians – namely, vitamins B12 and D, as well as DHA and EPA. Though not assessed, we also suspect that iron status was poorer in vegetarians in this study even though iron intake was similar; non-haeme iron from plant sources is less well absorbed than that from meat, so iron recommendations are 1.8 times higher for strict vegetarians.
Although Rizzo et al. (1) did not show data, they indicate that strict vegetarians were LESS LIKELY to take supplements than other dietary patterns, which is definitely concerning as this group is most at risk for deficiency. If you are new to vegetarianism or just want to make sure you are getting all the nutrients you need, talk to a dietitian. This is particularly important for vegetarian women who are planning to get pregnant. Here are some tips for vegans and foods for a healthy vegetarian diet.
Check out our Top Ten Reasons to Choose Vegetarian for more on the benefits of a plant-based diet.
- Rizzo NS, et al. Nutrient profiles of vegetarian and nonvegetarian dietary patterns. J Acad Nutr Diet 2013; [Epub ahead of print].
- Craig WJ, Mangels AR; American Dietetic Association. Position of the American Dietetic Association: vegetarian diets. J Am Diet Assoc 2009; 109(7):1266-82.
- Fulgoni VL 3rd. Current protein intake in America: analysis of the National Health and Nutrition Examination Survey, 2003-2004. Am J Clin Nutr 2008; 87(5):1554S-1557S.
- Kris-Etherton PM, et al. Position of the American Dietetic Association and Dietitians of Canada: dietary fatty acids. J Am Diet Assoc 2007; 107(9):1599-611.
- Orlich MJ, et al. Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Intern Med 2013;173(13):1230-8.
*strict vegetarians/vegans can meet *almost* all of their needs with a well-planned diet; a few low-dose supplements will round out any gaps!