Generally vegetarianism can be healthy. Diets high in whole plant foods are known to confer health benefits, although the exact reason for the beneficial health effects of edible plants in not fully understood. Plants contain a number of essential and nonessential nutrients including vitamins, minerals, fibre and a range of bioactive phytochemicals, and these may explain the health benefits of plant based diets. Vegetarians have been shown to eat higher concentrations of plant foods than non vegetarians and this practice may confer particular health benefits. However, meat also contains a number of nutrients that are essential to the health, as well as accessory nutrients that may be required for optimal health. Therefore investigations into the differences between vegetarians and non-vegetarians can be interesting nutritionally, and observations of the differing nutritional intakes can provide insights into the health of each group. Generally the intakes of vegetarians has been well reported in the nutritional literature.
For example in one study1, researchers assessed the nutritional intakes of vegetarian children consuming different types of vegetarian diets. These included vegans, lacto-ovo vegetarians and lacto-vegetarians diets. The group of children consuming a macrobiotic vegetarian diet consumed less animal products than those consuming a more traditional vegetarian diet, as might be expected. This is because macrobiotic diets contain grains and vegetables as the staple foods, while animal products and highly refined foods are avoided. However the mean intake of vitamin D for the macrobiotic vegetarian diet was only one eighth of the recommended daily allowance (400 IU per day). As the recommended levels of vitamin D are now considered too low, it is highly likely that these children were deficient in vitamin D. In fact levels of alkaline phosphatase, an enzyme responsible for bone resorption, was elevated in these children, suggesting that their low vitamin D intake was negatively affecting their bone health.
Another nutrient that can be problematic for vegetarians in vitamin B12, This is because vitamin B12 is only present in foods of animal origin. This was reflected in the fact that vegetarians consuming eggs and milk generally has acceptable intakes of vitamin B12 that were inline with the recommended intake (2 to 3 μg per day). However, macrobiotic vegetarian children had intakes of vitamin B12 only half that of the more traditional vegetarian diet. The vegans fared even worse with intakes of vitamin B12 even lower than those of the macrobiotic vegetarians. Although the iron intakes of most of the vegetarian children reached the recommended intake (10-15 mg per day), haematological indices showed that a quarter of the children had mild anaemia. This may related to the low bioavailability of the non-haem iron in plant foods. Other nutrient intakes were in line with the recommended intakes for the children suggesting that in general their diets may have contained adequate nutritional content.
Dr Robert Barrington’s Nutritional Recommendation: Vegetarians can be very healthy. However, due to differences in nutritional intakes, care must be taken when planning a vegetarian diet. In particular it is recommended that a vitamin B12 supplement is taken by all vegetarians who do not consume animal products. In addition, the low bioavailability of iron in plant foods necessitates the use of iron supplements or special care in obtaining an adequate iron intake without the presence of inhibitors of iron absorption (such as tea and coffee, certain types of fibre and chelating agents like tannins). Because vitamin D is also mainly present in food of animal origin, a supplement of vitamin D must be taken when sun exposure is not able to provide adequate levels of the steroid hormone. However, this is also true for omnivores as it is now becoming clear that dietary intakes of vitamin D are not able to supply adequate levels of the compound in most cases.
RdB
