From all over the world have come the most exciting findings ever reported about vitamin A. More than a dozen studies have linked diets rich in vitamin A to a surprising amount of protection against some forms of cancer.

In Chicago, scientists found only two cases of lung cancer among 500 men, including some smokers, who eat many fruits and vegetables rich in vitamin A. That was only one-seventh as many lung cancer cases as were found in 500 men who ate few of these foods.

And in Norway, the findings were no different. Men who ate many vegetables rich in vitamin A had only one-third as much lung cancer as those eating little of these foods.

In Japan, the story was the same. Researches found 30 percent fewer cases of lung cancer among people who ate vegetables rich in vitamin A every day. The daily vegetable eaters also had lower rates of stomach cancer.

Cancer scientists have been so fascinated by these findings that the ability of vitamin A to protect us from cancer has become one of their top interests. Many are already convinced that we should be eating more foods rich in vitamin A. The Committee on Diet, Nutrition, and Cancer of the National academy of sciences has urged us to do so.

Studies have linked a diet rich in vitamin A to protection from cancer in eight different organs. The evidence is strongest for cancer of the lung, stomach, or esophagus.

But there is more good news. Research also ties vitamin A to protection from cancers of the mouth, colon, rectum, prostate, and bladder. There is less evidence here than for lung, stomach, and esophageal cancer. But there is enough to merit our attention.

Three Types of Vitamin A

“Vitamin A” is very general term. It refers to several substances that can take care of the body’s need for this nutrient.

For many of the body’s functions that need vitamin A, any form will do. But in cancer prevention, the picture looks different. As things stand right now, it seems that only some kinds of vitamin A in food.

• Retinol is the vitamin A in animal foods.
• Carotene, (or beta-carotene) is the main kind of vitamin A in fruits and vegetables.
• Carotenoids are other forms of vitamin A found in fruits and vegetables. They are a very minor source of vitamin A.

Of these different kids of vitamin A, carotene is linked most strongly to protection from cancer.

….carotene is linked most strongly to protection from cancer.

Vitamin A Supplements Are Different

Of course, we can also get vitamin A from pills. The form used in vitamin compounds is not carotene or retinol. It usually is a synthetic form of vitamin A called vitamin A palmitate. Little research has been done on the ability of this kind of vitamin A to protect against cancer.

For this reason, it is not good idea to rely on vitamin A pills to reduce your risk of cancer. Scientists simply don’t know if this type of vitamin A has any value in preventing cancer.

You may also be aware that the kind of vitamin A usually contained in vitamin capsules or tablets can be toxic if taken in very high doses.

Newspapers and magazines have published some articles about special forms of vitamin A that show remarkable anti-cancer potential in laboratory animals. Scientists have used these forms of vitamin A, called retinoids, to block cancers of the lung, bladder, and breast in test animals.

Retinoids may be on the drugstore shelves someday. But right now they are not for sale. Their use is strictly experimental.

The Recommendation and How to Meet It

The Committee on Diet, Nutrition, and Cancer recommends daily consumption of fruits and vegetables. The committee advises us to emphasize those fruits and vegetables that are rich in carotene, the most important kind of vitamin A in plant foods.

To help in selecting foods, the Committee prepared the following chart which classifies foods as low, medium, or high in carotene.

Carotene in Fruits and Vegetables

Note: Chart adapted from a 1989 compilation by the Committee on Diet, Nutrition,

and Cancer, National Academy of Science, U.S.A.

Before I continue to write this subject, I suggest you to find another point of view concerning the power of vitamin A in  fighting cancer, a useful  article for you posted in Blog of Health.

( The next Story )

I would drink my orange juice and eat my green peppers even if  it weren’t  for research linking vitamin C to prevention of cancer.

Some of my reasons are the same ones that bolster the advice to eat more fruits and vegetables that supply carotene.  Like these plant foods rich in vitamin A, foods rich in vitamin C are also low in saturated fat and sodium.

What’s more, fruits and vegetables that contain vitamin C are cholesterol-free. And they provide small to moderate amounts of dietary fiber. Eaten in large amounts,  the fiber in these fruits and vegetables helps to lower blood cholesterol levels.

There is more. Vitamin C is rarely recognized for its role in iron absorption. Yet we have known for many years that vitamin C helps the body to absorb iron.

The extent of iron deficiency in the United State and most industry countries have been greatly exaggerated, I believe, but there are probably more people taking in too little iron than is the case for other nutrients.

Because the body absorbs only about 10 percent of the iron taken in, factors that increase iron absorption are just as important as iron-rich food. In fact, some scientists believe that increasing absorption of iron, rather than boosting iron intake, is the key to improving iron nutrition. They may be right on target.

At moderate levels – such as 50 to 100 mg – vitamin C has been found to improve iron absorption by as much as 50 percent. Higher doses may result in even higher absorption. But very few of us truly need such as assist.

Vitamin C helps the body absorb iron in foods that are eaten at the same meal. The vitamin C in breakfast foods, for example, has little or no effect on the iron in foods eaten at lunch or dinner.

For some people, however, this is not good news. A small number of people have a condition that causes them to retain too much iron, which accumulates in various organs, causing health problems. People who have this condition should consult their physicians for advice about diet.

I would love to tell you that vitamin C will also help protect you from heart disease. But I cannot, because I am not at all convinced by these claims.

I have looked carefully at evidence that vitamin C lowers blood cholesterol levels. But I found other studies in which vitamin C supplements appeared to have raised the cholesterol level. Some studies show no difference. I really do not hold out much hope for an effect here.

But what more can you want from vitamin C? It does not have to play a role in prevention of every disease in order to be taken seriously.

In my opinion, vitamin C is as important today as it was two centuries ago, when the mysterious disease  called scurvy threatened the lives of sailors who spent months without fresh fruits and vegetables. It is hard to disagree with the advice to make more room for this familiar vitamin in our diets.