If you are nutrition-minded, you probably try not to lose nutrients in cooking.

With vitamin A, you don’t have to worry. It is tough stuff; pretty much indifferent to water, heat, and even long periods of storage. Vitamin A doesn’t dissolve in water, so it doesn’t leach into water used in cooking.

But vitamin C is very sensitive. Heat, light, and oxygen can do it in. In fact, some loss of the vitamin C in food just cannot be prevented.

With a little effort, though, losses of the vitamin can be kept to a minimum. Here are the rules:

1. The sooner fresh foods can be used, the better. Vitamin C breaks down during storage.
2. Try not to chop these foods finely all the time. The fewer pieces a food is cut into, the lower its exposure to oxygen, which destroys vitamin C.
3. The vitamin C in cabbage, cantaloupe, squashes, and strawberries is especially unstable. The sooner they are eaten after cutting, the better.
4. When using water to cook foods rich in vitamin C, boil the water first. Then add the food and cover the pot tightly. This cuts down on the oxygen coming in contact with the food.
5. Cook vitamin C-containing foods in as little water as possible. The vitamin can leach into the cooking water. Steaming in a basket or pressure-cooking is better, because less liquid will come into contact with the food.
6. If you do cook these foods in water, use the cooking water to make a sauce or save it for stock. This way, you won’t pour vitamin C down the drain.
7. Keep cooking time to a minimum. The longer the food is cooked, the more vitamin C will lose.

It is not always possible, of course, to follow these rules, but when it is, do so. The vitamin will also hold up better if not heavily exposed to light.

About Frozen Foods

All of this talk about losing vitamin C must make you wonder if any of it is left in processed foods. The answer is: it depends.

In some cases, the ability of the food industry to preserve the vitamin C in food is no less than amazing. In other instances, though,  it seems that processors are not trying hard enough.

My favorite example is frozen orange juice concentrate. It contains hardly a milligram less vitamin C than the oranges that it hails from. The juice processors have perfected their trade so well that it is almost an art.

Many other frozen foods do lose some vitamin C during the trip from field to supermarket. But their fresh counterparts are likely to do so, too, during storage and cooking. So, though fresh, raw vegetables usually have the most vitamin C, once cooked, their C content may be on a par with that of frozen foods.

If you observe the rules on preserving the vitamin C in foods, your fresh, cooked vegetables may retain more vitamin C than frozen ones.

Is There Vitamin C in That Can?

For canned fruits and vegetables, the story is not so good. Canned foods often have less vitamin C than frozen or fresh foods. The vitamin C leaches into the water used in packing.

So even though a canned food might have a lower cost per pound than the fresh or frozen version of the same item, it is not necessarily the best buy. If the canned version has only half as much vitamin C as the frozen, for instance, it actually can cost more to get 20 mg of vitamin C from it.

I do not want to imply that canned foods have no nutritional value. Nor do I mean to say that canned foods should never be used. But nutritionally, frozen foods are often a better buy. When in season, fresh foods are often a better buy, too. And fresh or frozen foods usually have less salt – a big plus.

You almost always can depend on fresh, uncooked foods for vitamin C (provided that the food is a source of the vitamin). When you eat fresh, raw foods, you don’t have to give a thought to losses that occur during cooking.

Remember: the vitamin C that remains in frozen or fresh foods can be destroyed by too much exposure to heat, light, and large amounts of cooking liquid. But a little effort can go a long way toward preventing unnecessary losses of this important vitamin.

I suggest you to find other valuable stories concerning vitamin C and cancer as follows:

• Vitamin C and Cancer
• Vitamin C, Cancer, and Kidney Stones
• Vitamin C, Cancer, and Kidney Stones, Part II, and
• Protect Yourself Against Cancer with your Daily Foods

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 )

The cabbage family is not the only group of foods that has shown potential to block the cancer process. Other foods may also have this ability – and some may be even more potent than foods of the cabbage family.

But the evidence for these other foods is not as strong. Some foods have inhibited cancer in studies on animals, but studies with humans have yet to be done. Other foods have been studied in only one or two experiments – too few for judgment. This is why some health institution such as Committee on Diet, Nutrition, and Cancer limited its recommendations to the cabbage family.

Of the other foods that might also contain inhibitors, the evidence is best for citrus fruits. The beneficial effect of these foods has ranged from weak to potent in studies with animals.

As for other foods, the evidence is just beginning to come in. But for your information, I would like you to know some of the possibilities now under further study:

• Celery and spinach have shown slight but significant inhibiting ability.
• Soybeans and lima beans have also shown some potential.
• Grains and vegetable oils may contains a substance with moderate inhibiting power.
• Green coffee beans have shown a powerful inhibiting effect in early studies. But roasted and instant coffee have shown only a weak effect.

Remember: for some of these foods only several studies have been done. This is far too little work to justify changing your diet.

Some Unanswered Questions

Scientists are still a little cautious about the cancer inhibitors in food. They aren’t 100 percent convinced that these substances are only beneficial.

The Committee on Diet, Nutrition, and Cancer tells us that its matter of weighing the pluses and minuses. On the balance, the panel scientists agrees that the good points of the cabbage family vegetables outweigh the bad points.

What are the bad points? Mostly, they fall under the label of “uncertain effects.”

As noted earlier, inhibitors seem to activate an enzyme system that is thought to detoxify harmful chemicals. There is some concern that this very same enzyme system may also enhance the power of some chemicals. In other words, the enzyme system may have both good and bad effects.

Despite information on this subject is incomplete, still,  the scientists recommend that we eat citrus fruits, whole grains, and cabbage family vegetables. Obviously, the scientists think that the pluses here outweigh  the minuses.

But until this question is settled, it is best not to go all out with cabbage family vegetables. Eating them often – but not exclusively – is probably the best course of action. Including them in your diet once or twice a week is a cautious, moderate approach.

Putting It All Together

Up to this point, you have read a great deal about fruits, vegetables, and grains. It is fitting, I think, to take a broad look at these foods to see how they score when all protective factors are taken into account.

There are four factors to consider: vitamin A, vitamin C, insoluble fiber, and inhibitors. To take a simple approach to these four factors, I have devised a rating system.

I gave a food one point if it contains a moderate amount of vitamin A and two points for a high level. I used the same system for vitamin C and for insoluble fiber.

I then awarded two points to the four members of the cabbage family that appear to contain a cancer inhibitor other than vitamin A and C or fiber. I gave one point to the other foods that might have a cancer inhibitor.

The Top-Scoring Cancer-Blocking Foods

When all the points were tallied, broccoli and brussels sprouts topped the list.

They were followed by some vegetables that many people eat little of: collards, kale, kohlrabi, mustard greens, and rutabagas.

But in third place were some familiar faces: oranges, grapefruit, cabbage, cauliflower, lima beans, and spinach. Watercress also rated with this group.

Chances are that you like some of these foods. Pick the ones you like best, and continue to enjoy them.

If you do, then you should think again. Exciting new research shows that nature gives us weapons that can fight back. And these weapons are not in exotic places. They are in common foods.

The substances I am talking about are not considered nutrients, because their absence does not cause a deficiency disease. These substances are little-known food elements. Only a handful of research scientists are familiar with them.

Scientists call them inhibitors. In laboratory animals, these substances show an impressive ability to inhibit the cancer process.

How Cancer Inhibitors Work

A cancer agent, such as one found in cigarette smoke, might cause cancer in half of the animals that are exposed to it. But when an inhibitor is given along with the cancer-causing chemical, fewer animals will develop cancer. The inhibitor prevents the cancer-causing chemical from doing its damage.

Exactly how inhibitors work is not known. But the best theory right now has to do with an enzyme system in the body’s cells. It is called the mixed function oxidase system. Scientists believe that this enzyme system may actually have the power to strip dangerous chemicals of their harmful effects.

Cancer scientists have been curious about inhibitors for a very good reason. Human studies do support the notion that certain foods help to block the cancer process. Several studies have found that people who often eat foods thought to contain inhibitors have less chance of getting cancer.

The Organs That Benefit

For the most part, inhibitors are linked to protection against cancer of the digestive organs. Research ties these inhibitors most strongly to reduced rates of stomach and colon cancer.

Cancer inhibitors may help to explain why many people who are exposed to cancer agents never develop cancer. Think about it. Everyone has been exposed to cancer agents. They are in the air. Or in the water we drink. Or in the work place. And sometimes in our food.

Why, then, does cancer strike one in four – not four in four?

A good intake of cancer inhibitors may be part of the answer.

The Recommendation and How to Meet It

The Committee on Diet, Nutrition, and Cancer took a close look at research on cancer inhibitors. The committee made one recommendation after looking at these important findings.

The recommendation advises us to emphasize foods belonging to the cabbage family of vegetables. There is good evidence that these foods contain cancer inhibitors other than vitamins A and C.

The most common foods of the cabbage family are broccoli, cauliflower, brussels sprouts, and of course, cabbage. Research has linked these four vegetables to reduced risk of both stomach and colon cancer. A few studies also link these foods to lower risk of rectal cancer.

There are other foods in this family of vegetables. But it is not possible to say whether these other foods are also linked to lower risk of these cancers. It is reasonable to believe that these other foods are more likely than not to contain the same cancer-blocking substances. But only further research will give a firm answer.

The following chart lists all the foods belonging to this family.

The Whole Cabbage Family

A Family of Many Names

Scientists have some strange jargon for the foods of the cabbage family. The most technical name for this group of foods is the Brassica family. They also refer to these foods as “cruciferous” vegetables.

The inhibitors found in broccoli, brussels sprouts, cauliflower, and cabbage have been named indoles. Research on indoles is so recent that tables listing the indoles content of foods are nowhere to be found. So it is not possible to rank foods by their indole level. Also it is not known whether cooking and storage influence the indoles in these foods.

The best advice is to select the foods of this family that you like best and eat them often – perhaps once or twice a week. Remember that many of these foods offer other bonuses: vitamin A or C, a low fat and sodium count, and a modest amount of dietary fiber.

( next story: the Part II )