Plant based diets confer health benefits to humans. This relates to the high concentrations of phytochemicals contained within the plant foods. Plants are rich in fibre, vitamins and antioxidants and these components provide a substantial amount of the health benefits of eating plants. The mineral content of plants is also important however, the mineral content of plants is dependent on the soil upon which the plants have been grown. Low mineral soils produce low mineral plants, and these plants in turn produce low mineral animals that are susceptible to mineral deficiencies. Vegetarians eat high plant diets and studies show they benefit from the health benefits conferred by plant foods. Some evidence has suggested that high fibre intakes in such diets may interfere with mineral absorption and lead to poor mineral status in those who consume them. For example, phytate is often cited as a component of fibre that can bind minerals in the gut and prevent their absorption.
However, vegetarians have been reported to have adequate mineral status in some studies, suggesting that the influence of phytic acid might not be significant. For example, in one study1, the iron and zinc status of a number of long term vegetarian women was assessed in relation to the dietary fibre content of the diet. The dietary records of the women showed that plants provided 92 and 77 % of the total iron and zinc in the diet, respectively. Intakes of iron and zinc were 12.5 and 9.2 grams per day, respectively, which is a reasonably good intake of both minerals. The dietary fibre intake of the women was also high at 30.9 grams per day, well above the fibre content of the typical Western diet. The haemoglobin, serum transferrin saturation, serum zinc and hair zinc concentrations were all within the range expected of healthy individuals. Therefore it would appear that in this group of Seventh Day Adventist Canadian women at least, the zinc and iron status was not affected by the high fibre content of the diet.
Analysis of the diets of the women in this study showed that the iron density of the diet was 7.7 mg per 1000 kcal, This value is higher that the Canadian national average which was measured in the Nutrition Canada Survey at 6.0, 6.4 and 6.5 mg per 1000 kg for young, middle aged and elderly women, respectively. Both the zinc and iron intakes of the women were also above the Canadian recommended values. Of course, it could be argued that the vegetarian women are reliant on the non-haem form of iron from plants to maintain adequate mineral status. As non-haem iron is less bioavailable than haem iron from animal sources, the higher iron intakes of the vegetarian women could be negated somewhat by the less bioavailable form. However, this does not appear to have affected the iron status of the women significantly. Further, the authors did report that the diets of the Seventh Day Adventist women in this study were of particularly high quality compared to previously investigated vegetarians.
Dr Robert Barrington’s Nutritional Recommendations: vegetarian diets can be healthy. Most traditional diets are based on plant foods and the vast majority of the World’s population does not eat meat. In fact the United States of America makes up only around 5 % of the World’s population but consumed over 30 % of the animal produce. The physiology of our guts suggest that we are omnivorous by nature, but that does not mean we must eat meat. Recent advances in the production of high quality low fat sources of protein such as whey mean that the protein content of meat is no longer a prerequisite to health. However, one of the advantages of eating meat is the highly bioavailable iron it contains. But as iron deficiency is the most common nutritional deficiency in Western nations, this suggest that high per capita consumption of meat is not the solution. There is no tangible reason why plants cannot supply adequate iron if the diet is carefully selected and proper nutritional consideration given to food choices.
RdB
