Vegetarian diet

What should you say to the patient who asks about vegetarian diet? Is it safe? Can it be recommended during pregnancy? What are the main risks associated with it? As more and more people consider this nutritional option, particularly younger women, these are common questions that face the GP.

The first thing to remember in approaching the vegetarian question is that it is perfectly possible to get a complete nutritional balance without eating meat, or indeed any animal products. Not only is a good vegetarian diet adequate, but quite a lot of research has established some significant health pluses. These include lower levels of heart disease, hypertension, various forms of cancer and even osteoporosis. Many studies have confirmed that children and adults alike can thrive on a vegetarian diet, and therefore there is no reason for the GP to be hesitant in counselling a patient who is interested in this dietary lifestyle.

But this does not mean a carte blanche safety clearance. There are definite nutritional risks associated with such a diet, some leading to potentially very serious diseases. The first and most obvious risk is that a patient who calls themselves "vegetarian" may actually not be pursuing a vegetarian lifestyle at all, but some other faddish or restrictive diet which they happpen to be labelling vegetarian. Some of the more extreme forms of macrobiotics which flourished in the 1970s were good examples. Another good example to watch out for the teenager (especially teenage girl) in whom vegetarianism proves to be an effective and socially respectable mask for their eating disorder. Wherever possible I personally like to assess the healthiness of all my patients' underlying attitudes to eating and food. This is particularly important in teenagers and others at risk for eating disorders.

On a less extreme note, I have seen many vegetarians whose nutritional knowledge left much to be desired, even though they are following a lifestyle framed in dietary terms. Many factors apart from health considerations can motivate a patient's interest in vegetarianism - ethical, ecological, sociological or sometimes just a distaste for animal foods. By no means all of these guarantee knowledge or even interest in nutrition and cooking.

Some vegetarians are remarkably ill-informed about food. They may believe that a vegetarian diet consists of eating vegetables, and eat little else. They may have no idea that a proper vegetarian diet is based around grains and legumes, not vegetables. The single male, teenagers, and the semi- or de facto vegetarian (they have never thought of themselves as vegetarian, but just do not happen to eat much meat) are the most likely to fall into this category.

Common dietary mistakes

On a dietary level, the most common mistakes vegetarians make are:
1. Over reliance on vegetables and fruits: at the expense of grains and legumes
2. Eating too much fat: for example excessive servings of eggs and dairy produce
3. Developing a `sweet tooth': consuming excessive fruit, refined and other simple carbohydrates
4. Repetitious diet: chosen from too narrow a range of foods, due to ignorance of the many alternatives.

Clinical complications

On a clinical level, such problems might manifest in malaise and tiredness, complaints which are surprisingly common in the less nutritionally careful vegetarian. More specific nutritional deficiency states may be present. Vitamin B₁₂ deficiency is one. Apart from causing macrocytic anaemia, this condition can have neurological complications. Remember that neurological damage has been reported in patients with relatively mild or borderline low serum B₁₂ levels and certainly without changes in the blood film. The consequences can be serious indeed, particularly in infancy. Although the risk is less for those vegetarians who eat dairy and eggs, it is by no means absent. Nor is it always the case that it takes several years for deficiency to develop, as the textbooks sometimes suggest. Hence, the GP should check serum B₁₂ levels in every vegetarian patient (and repeat this test at least biannually) and routinely in every pregnant vegetarian woman.

An more prevalent but less sinister problem is iron deficiency. Common enough even amongst meat eaters, the inorganic iron in the vegetarian diet is much less well absorbed than the haem iron in meat, so that as many as 30% of some groups of vegetarian women have been shown to be iron deficient. Check the serum ferritin at least annually in all female vegetarians, and in male vegetarians based on other risk factors (such as blood donation) or the clinical picture.

Zinc is found in much the same foods as iron, so that zinc deficiency may also be common in vegetarians, Unfortunately it is not easy to test for it, and so zinc deficiency should be treated as a presumptive diagnosis to be ruled out wherever iron deficiency is also present.

Once diagnosis is made, iron deficiency is a relatively easy condition to correct. Grains, legumes and nuts are the best iron-containing vegetarian foods. Vegetables such as cabbage, cauliflower and broccoli are much better sources than the much overated spinach. Those who are prepared to eat even a little meat will find it assists not only with its own haem iron content, but also in enhancing non-haem iron absorption. Otherwise increased consumption of vitamin C-rich foods and less iron absorption inhibitors (tea, phytate) with the main iron containing meal are helpful.

Another deficiency occasionally seen in vegetarian patients is a borderline lack of vitamin B₁ (thiamine). This is mainly seen in those vegetarians who consume little in the way of nuts, grains and legumes. It presents its most potentially serious clinical manifestations in vegetarians who also consume excessive alcohol.

Summary

In summary, the GP should maintain a positive encouraging approach to vegetarianism, but without abandoning the proper careful check for the high risk patient and possible nutritional deficiencies and imbalances. This particularly applies to the casual or semi-vegetarian, teenage girls and the single male.

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