Warning against pill 'popping’ Vitamin A is vital in right amounts

Press, 13 November 1982, Page 10

Warning against pill 'popping’ Vitamin A is vital in right amounts

Good eating

Janice Bremer DIETITIAN

Vitamin A is certainly in the news!

Last week Professor Don Beaven described a study in which a relationship had been found between a low vitamin A intake and the incidence of heart and peptic ulcer disease.

Only a few months ago we heard from the United States National Academy of Sciences that vitamin A, along with vitamin C, seems to offer protection against some cancers. And with

these reports we are warned against "popping”vitamin pills, specifically that vitamin A can be toxic in'large doses.

So how do we check out our vitamin A quota? And how do we improve it? One of the first symptoms of a lack of vitamin A is night blindness. Its nutritional cure has been known for thousands of years. Ox liver was found to be a cure as early as 1500 B.C. True vitamin A or retinol,

is found only in foods of animal or fish origin associated with the fat component. This is preformed vitamin A.

Liver, where vitamin A is stored in animals, is the highest animal source. Plant foods such as carrots and green vegetables in particular, contain provitamin A (carotene and carotenoids) which can be converted into retinol in our intestines, and is potentially our major source of vitamin A for the recommended pattern of eat-ing-for-health.

It is also this “carotene” that is 'associated with the lesser.risk for some cancers. Foods rich in carotene are prized also for the other vitamins that can be missed by non-fruit-and-vegetable eaters. Vitamin 86, folic acid, vitamin C, riboflavin, and some other B vitamins are found in the rich-source foods listed in the table. (Fruits have varying amounts of carotene but are generally low.)

This leaves us with our "traditional” sources of vitamin A, — butter, milk and eggs, — as less important, in keeping with recommendations that we eat less fat. There has been concern expressed that lowering our butter and milk consumption will place us at risk for vitamin A deficiency. This comment is appropriate only for infants and very young children, who have a limited capacity for converting carotene into Vitamin A and who incidental!}' do not eat large amounts of vegetables. They should continue to have whole milk, rather than "non-fat” milk, (but do keep on with the green vegetables and carrots). Too little?

Who has too little vitamin A? Most likely anyone who eats few green or yellow vegetables, is not interested in fruit, has little whole milk, and never eats liver.

Foods with none or only trace amounts of vitamin A, are cereals and cereal foods such as breads (unless they are fortified), white fleshed vegetables, nuts, dried pulses, meats, chicken, white fleshed fish, shellfish, non-fat milk products, sugars.

As our first consideration for adequate nourishment is concerned with calories or energy supply, it is appropriate to evaluate foods for vitamin A content by comparing the micrograms of vitamin A per calorie of consumed food.

This method of comparison accounts for fat (fattening or

atherogenic) calories as a less desirable major meal component, not to be overrated as a source of vitamin A. The richest source of vitamin A becomes cod liver oil, with 20 migrograms of vitamin A per calorie, but this is not a regular ingredient of our meals. Lambs fry furnishes 78 micrograms per calorie; carrots 75 micrograms per calorie; watercress and spinach, 35; broccoli, 23; pumpkin, 17; lettuce, 13; apricots, 9; kumara, 8; and tomatoes, 7. Butter contains only just over 1.1 micrograms of vitamin A per calorie, with cream and cheese a little less, and whole milk only half as much as butter. Fortified polyunsaturated margarine has a slightly higher vitamin A content than butter. Eggs, often considered a rich source, supply only 2 micrograms of vitamin A per calorie. So eating vitamin A from foods of vegetable origin is a thrifty way of spending calories! Daily quota Let us now look at how to achieve our daily quota. The average adult requires each day, 1000 micrograms of vitamin A or vitamin A equivalents (which is carotene converted to vitamin A). The following table gives the amount of food to yield 100 micrograms of vitamin A, so that ten servings of one or ten selections gives the quota. Just one small carrot gives the full daily need! Lambs fry and chicken livers are so rich in vitamin A that for 100 micrograms it is a mere speck — less than one gram, an absurd measure for inclusion in the table! One small piece of lambs' fry yields sufficient vitamin A for a full week. 100 micrograms vitamin A

Rich sources — have large servings

asparagus six slender spears green beans one cupful broccolione “flowerette" (1% cup) brussels sprouts seven small cabbage 3 cups sliced raw, 1H- cups cooked carrots 2 teaspoons spinachone level tablespoon cooked lettuce 5 leaves cress one heaped tablespoon peas Hi) cups pumpkin ‘-z small piece kumara one tablespoon tomatoes one large apricots one bananas 2 large peaches 1 large paw pawone fifth of whole fruit plums six Moderate sources ■ milk 300mls (v 2 bottle) cream 2 tablespoons butter 2 1 i level teaspoons fortified margarine2 level teaspoons eggs 2 small cheese one thin slice cottage cheese one cup eel one tablespoon kidneys IV 2 sheep's Warning The last caution; vitamin A “popped" daily as six thousand micrograms in tablet form (may be written on the bottle as 20,000 International Units) for a period of one to two months is likely to be toxic, according to a joint committee on Nutrition, and Drugs trition, for the American Academy of Pediatrics. It warns that the hazards of vitamin A poisoning are considerably greater than those of vitamin A deficiency. Liver damage is the side effect of this pseudo “nutritional insurance.” Massive doses of carotene are not converted to vitamin A rapidly enough to cause g vitamin A poisoning, but an excess does accumulate in the body. A grossly excessive consumption of vegtables high in carotene, such as carrots produces few symptoms other than a yellow or orange skin. Cancer There is convincing evidence in animals for a role of lack of vitamin A in cancer, but there are as yet many questions unanswered by human studies. The association found between a low vitamin A intake and the incidence of cancer may be caused by other life-style variables. Low vitamin A levels

found in the blood of cancer patients may be an “effect of,” just as much as the “cause" of cancer. However, recent works show that the later may indeed occur. As it remains feasible that a defence mechanism(s) of the body for controlling potentially cancerous cells could rely on an essential nutrient such as vitamin A, it is good sense to maintain good nutrition in respect to vitamin A. Along with all the other nutrients essential to our healthy survival and provided by “good eating,” Vitamin A may have impact on the incidence of the major diseases of western civilisation, and on longevity.