Diet Dilemma

With people getting more and more conscious about their health more emphasis is now being laid to adopt lifestyle that is good for persons wellbeing and for this we take necessary actions also. We are inquisitively looking for information regarding this. But when it comes to food we are unquestioning about what we eat because we believe a balanced diet gives all the nutrients we need. In reality, however, we may well be getting less than we expect because of a group of compounds called nutrient inhibitors. They bind with valuable nutrients and make them unavailable for absorption in the human gut.

Probably the trickiest of them all are oxalates which bind with calcium and magnesium. Oxalates are found in green leafy vegetables, raw plantain and plantain flower, which is used as a vegetable, nuts, gingelly seeds, drumstick, Indian gooseberry, cocoa, chocolates and tea. Oxalate rich food items do not yield the nutrients they hold hostage.

So, while we may list green leafy vegetables as an excellent source of calcium and magnesium, we infact, hardly get the benefit of these nutrients because they are bound to oxalates. The way round this problem is to get clever. For example, by eating food rich in calcium and magnesium, such as curd and daals. Even if they are included in the same meal there is little chance that the bound oxalates in green leafy vegetables will have any detrimental effect.

Phytates, another group of inhibitory substances, are found in the bran of whoel grain cereals, legumes, pulses, nuts, oil seeds and spices. But phytates ae slightly more easy to handle. They can be broken down by an enzyme called phytase produced by yeast and in the human intestine.

So yeast, fermentation of foodstuff should be encouraged at all times, especially since resorting to the use of refined cereals (polished rice and maida, for instance), which contain no phytates, comes with a host of other more worrisome problems.

Radish, tunips, cabbages, cauliflowers and Brussel sprouts, besides groundnuts, soya beans, legumes and lentils come with an entirely different problem, thanks to the presence of a group of substances called goitrogens. These prevent the utilization of iodine by the thyroid gland if iodine – rich foodstuff are eaten at the same time. Thankfully, goitrogens are readily destroyed when these foods are cooked.

Trypsin inhibitors are those compounds which interfere with the activity of trypsin, the enzyme that digests proteins in the small intestine. Soyabeans, legumes and egg white contain these compounds. These are high – protein food items as well.

Trypsin inhibitors however are destroyed by cooking, especially if pressure cooking is employed. So we don’t exactly have a problem here, unless, of course, you fervently believe the healthy way to start the day is with an egg nog, a drink which is a concoction of raw egg, milk and other ingredients.

Similarly heavy tea drinkers will have to think twice before sipping their nth cup of tea. Tea contains tannins that bind vitamin – B and iron. Tannins are also found in many species, tamarind, ragi, bajra and in the seed coats of legumes. We do not manifest beriberi or anemia, caused by the deficiency of vitamin –B or iron in our diets, because other food items provide these nutrients, not just those rich in tannins. Niacytin found in cereals grains, especially maize, renders vitamin –B3 unavailable. The most effective way to release vitamin B3 from this bond is to treat the food with slaked lime (chuna).

In foodstuffs of animal origin, avidin is the compound in egg white that binds with a B –Vitamin called biotin and thiamin, an enzyme found in clams and shrimp, inactivates viamin – B. Both these nutrient inhibitors though, are destroyed by ordinary cooking temperatures.

Despite these problems, the reason we seldom suffer nutritional deficiencies is because we nearly always eat a varied diet unless lack of purchasing power limits us to a nutrient restricting staple. Interestingly, though, when you have a line-up of foodstuff that contains calcium, magnesium, zinc, vitamin –C and D, and viamin – B12, you may be mighty pleased with the composition of your meal. Until, of course, you realize that not all of them are happy in each other’s company.

This is because may of them compete for the same absorption sites in the intestines. For instance, calcium interferes with the uptake of magnesium from the gut, and vice versa, if two of them are present in the same meal, or worse, as in the case of green leafy vegetables, in the same food. Zinc is affected by the simultaneous presence of calcium and vitamin –D; large amounts of vitamin – C and vitamin – B12 in the same meal also do not benefit us.

Alcohol, smoking, the oral contraceptive pills and medication also affect the utilization of nutrients. Zince and many vitamins of the B – complex group, notably, vitamin – B1, B6 and B12, pantothenic acid and biotin are adversely affected by high alcohol consumption. Cigarette smoke destroys vitamin –B6 and B12. The oral contraceptive pills depletes vitamin B6 and zinc.