tudies have shown that vegetarian diets may hold health benefits over those of non-vegetarian diets. This reflects the fact that in general, vegetarians consume more plant based material than non-vegetarians. Plants are a good source of soluble and insoluble fibre, higher intakes of which are associated with lower rates of obesity, metabolic syndrome, cardiovascular disease and some forms of cancer. In addition, plants contain phytonutrients that may have health benefits. For example, flavonoids and carotenoids may function as antioxidants in human plasma and cell membranes, respectively, reducing the overall burden of oxidative stress. Higher intakes of plant foods also decrease intakes of some forms of processed meat which lowers intakes of nitrates that are associated with carcinogenesis. However, while vegetarian diets possess some benefits, vegetarianism can be problematic with regard some nutrients. This reflects the low availability or absence of particular nutrients in foods of plant origin.
Nutrient intakes from vegetarians have been compared to intakes from non-vegetarians in order to assess the level of nutrition. For example, one group of researchers1 from France analysed the 7-day food diaries of healthy French vegetarians and compared the vitamin and macronutrient intake to those of a healthy group on non-vegetarian control subjects. In addition, the vitamin status of the subjects was assessed using biochemical tests from blood samples. The results showed that both groups of subjects had low intakes of pyridoxine (vitamin B6) with 68 % of vegetarians and 58 % of non-vegetarians having intakes below the French recommended allowance. Intakes of vitamin D were also below the recommended levels for vegetarians. Vegetarians had significantly higher rates of abnormally low levels of vitamin B12 (cobalamins) suggesting that vegetarians were at a higher risk of developing deficiencies of these vitamins.
These results suggests that vegetarians diets may be problematic with regard intakes of vitamin D, B6 and B12. Vitamin B12 is commonly deficient from the diets of vegetarians because it is produced by microorganism and present only in foods of animal origin. If care is not taken to include such foods then vegetarians can easily become at risk of vitamin B12 deficiency. Vegans, who eat no foods of animal origin must supplements with vitamin B12 to avoid developing deficiency and suffering serious health consequences. However, vegetarians did have higher intakes of β-carotene that non-vegetarians, reflecting the mainly plant foods of their diets. The non-vegetarians also had higher intakes of protein, saturated fat, total fat and cholesterol, reflecting the higher concentrations of these substances in foods of animal origin. However, the vegetarians had higher intakes of carbohydrate, but lower intakes of total calories.
In this study 98.5 % of the vegetarian and 87 % non-vegetarian subjects had vitamin D intakes below the recommended amount. For vegetarians these figures might have been lower due to the fact that vitamin D is present mainly in fish, which would not be consumed. Results from the biochemical tests showed that serum 25-hydroxyvitamin D [25(OH)D] was below 40 nmol/L in both vegetarian and non-vegetarian subjects, indicative of vitamin D insufficiency. Both vegetarians and non-vegetarians also had low levels of thiamine (vitamin B1) and pyridoxine (vitamin B6) based on blood test results. However, as expected, the vegetarian group had very levels of plasma ascorbate, probably due to their higher intake of plant foods. Therefore generally, while deficiencies are common amongst vegetarians, this problem also applies to non-vegetarians. Although the exact nature of the deficiencies might differ between the two groups.
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