Food for Life: How the New Four Food Groups Can Save Your Life (4 page)

In 1972, Boston researcher Micheline Matthews-Roth studied the effect of beta-carotene on the skin. In an unusual experiment, she fed beta-carotene to inmates at the Arizona State Prison for several weeks, then brought them out to the desert, where small areas of their backs were exposed to the sun for varying lengths of time. She found that beta-carotene made it harder to burn and easier to tan.
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This effect is relatively small, and it cannot protect you against prolonged sun exposure. On the other hand, sun damage to the skin is accumulated gradually. Day after day, the sun on our skin results in the effects we see later on. People who have the protection of a vegetable-rich diet every day may well have a long-term edge on the effects of the sun.
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Almost certainly, the beta-carotene dose has to be subtantial. Vegetable-rich diets are effective, as are supplements, but a tiny pile of green beans on the corner of your plate will not help much.

Beta-carotene is easy to find. Yellow and orange vegetables such as carrots, sweet potatoes, and pumpkins contain enormous amounts. All other green and yellow vegetables and fruits also contain beta-carotene: broccoli, spinach, peaches, cantaloupes, kale, collards, mustard greens, and so on. People who consume extremely large amounts of carrots or other beta-carotene-rich vegetables can even develop a temporary orange coloring in their palms and soles.

I do not recommend that you rush out and buy a beta-carotene pill. It is no substitute for vegetables. First of all, plants do not contain just beta-carotene. There are dozens of other antioxidants in plants, each with a slightly different role in protecting the body. In fact, there are dozens of relatives of beta-carotene, called
carotenoids
, found naturally in plants, and there are other vitamins in vegetables that work as part of the body’s antioxidant team. In addition, consuming a concentration of one antioxidant may reduce the body’s absorption of others.
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Vegetables, along with fruits, grains, and beans, provide nature’s balanced mix of antioxidants.

Sun is not the only thing that attacks the skin. Tobacco is very harmful to the skin, and over time causes an aged appearance. Antioxidants do have a limited capacity to counteract tobacco’s cancer-causing effect and possibly other tobacco effects, although this is not license to smoke. The effects of tobacco are so strong that vegetables cannot undo the risk to the lungs and other body parts.

Each cell in the body has an entire antioxidant system that it uses to neutralize free radicals. Beta-carotene is just the beginning. Vitamin C circulates in the bloodstream and is a very potent weapon against free radicals in the blood plasma.
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Like beta-carotene, vitamin C even has a limited power to protect against the free radicals formed by cigarette smoking.
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Where does one get vitamin C? Of course, there is vitamin C in citrus fruits, but there is lots of vitamin C in green vegetables. People who build their menus with vegetables and fruits get vitamin C at every meal. Unfortunately, meals in Western countries are typically not based on vegetables; they are based on meat and dairy products. Beef, pork, poultry, and fish contain virtually no vitamin C. Likewise, milk, yogurt, cheese, and other dairy products are very low in vitamin C. As you will see shortly, these animal products are not just lacking in the protective nutrients; they can actually increase the production of free radicals and create hormone havoc.

If vitamin C is in short supply, free radicals in the blood plasma can approach the cells of the body. At the outer surface of the cell is a membrane that carefully regulates what will and will not enter the cell. Free radicals attack that cell membrane, and can severely damage the microscopic machinery inside your cells.

Cell defenses in the membrane include stored vitamin E. This vitamin does not prevent the formation of free radicals, but it does stop chain reactions of molecular damage. Molecules of vitamin E are chemically altered in the process of neutralizing free radicals, but they are restored to fighting form by vitamin C.
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So, as you can see, these vitamins make a good team. Vitamin C patrols the bloodstream for free radicals. When it finds them, it knocks them out. Free radicals that get through to the cell membrane have to face vitamin E, and when vitamin E is damaged, it is “repaired” by vitamin C. Beta-carotene, which works in areas with different oxygen concentrations from those in which vitamin C is effective, completes the team.

Vitamin E is found in many vegetables, beans, grains, and fruits, especially beans, corn, and sweet potatoes. Nuts, such as almonds, are loaded with vitamin E, although their fat content is high.

Unfortunately, no one yet knows just how much beta-carotene or vitamin C or vitamin E is the optimal amount. The Recommended Daily Allowances
(RDA) were developed with an eye toward meeting the body’s basic needs, and generally do not take into account emerging information on the role of vitamins in immunity, cancer prevention, or slowing the aging process.

Researchers use doses of beta-carotene in the range of 15 to 30 mg per day, and in some cases as high as 180 mg per day. Beta-carotene is apparently safe even at considerably higher doses. The RDA for vitamin C is only 60 mg per day, but people interested in its antioxidant effects generally use larger amounts, ranging from about 500 mg to several grams per day. The RDA for vitamin E is 8 mg per day for women and 10 mg per day for men, but the optimal dose as an antioxidant is as yet not determined.

My own suggestion is to get these nutrients from foods rather than from supplements. Foods provide safe amounts of these nutrients, along with other helpful nutrients.
Table 1
shows how much of each is in typical foods.

Table 1     
Antioxidants in Foods

In addition to antioxidant vitamins, the cells of the body have built-in enzymes designed to break down free radicals. One of these, called
glutathione peroxidase
, is an enzyme whose name you do not need to remember. But it is worth knowing that, to work properly, this enzyme needs a certain mineral called
selenium
. Selenium is present in the soil, and plants take up selenium and bring it through grains to you in the form of bread, pasta, and so on. Unfortunately, the selenium content of the soil varies enormously from one area to another, so some doctors recommend taking small supplements of selenium—on the order of 50 to 100 micrograms (mcg) per day. If you choose to do this, do not exceed this amount, as selenium is toxic at high doses. If you also take a vitamin C supplement, take it at a different time, because vitamin C may interfere with absorbing selenium.

So far, we have looked at ways to soak up free radicals. Most people do not spend their evenings in the medical library, and therefore have never heard of free radicals. Vegetables, for them, may be nothing more than a side dish as they eat chicken breasts and skim milk, not realizing that healthful eating is something quite different—as the remainder of this book describes in detail. Among the consequences of a vegetable-depleted diet is that it does not produce adequate defenses against free radicals. The resulting damage occurs in the cells of the skin and the internal organs.

And there is something else you should know. There are ways not just to neutralize free radicals that form but to actually reduce their production in the first place. The key is to avoid foods that cause free radicals to form. What kinds of foods are they? Vegetable oils, fish oils, and iron all stimulate the production of free radicals. While they have enjoyed an undeserved good reputation in the lay press, they can be a big part of the free-radical problem.

First, let’s look at oils. All types of fats and oils promote the production of free radicals. Doctors correctly counsel patients to steer clear of saturated fat, such as that in beef or chicken, so many people thought there was no reason to be concerned about vegetable oils. The fact is, while animal fats are every bit as bad as you’ve heard, vegetable oils are not such health foods, either. Granted, they are not likely to elevate your cholesterol level, but they do contribute to free-radical production. The moral of the story is to keep
all
fats and oils to a minimum.

This is not to say that you should have no oil at all. A small amount of oil is intrinsic to foods—-corn contains corn oil, for example, and all other vegetables (even broccoli) have small amounts of intrinsic oil. The key is to avoid the added oils that are used in frying or in salad oils.

Even worse are fish oils, which actively encourage the production of free radicals. As you may know, fish oils have been popularized as an aid against everything from heart problems to arthritis. While not all of these claims have held up, scientists have taken an interest in a certain type of fat in fish called
omega-3 fatty acids
because they can reduce the level of triglycerides in the blood, which play a role in heart disease. (The name “omega-3” is simply a chemist’s term describing the structure of the fat molecule.) The bad news about fish and fish oils is that omega-3s in fish oils are highly unstable molecules. They tend to decompose and, in the process, unleash dangerous free radicals. Researchers from the University of Arizona
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and Cornell University
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addressed this problem in the
American Journal of Clinical Nutrition
, reporting that omega-3s are found in a more stable form in vegetables, fruits, and beans. And vegetables and fruits also provide antioxidants to help neutralize the free radicals that are produced. The body needs only a tiny amount of omega-3s, and vegetables, fruits, and beans provide the benefits of omega-3s while avoiding the more unstable forms. They concluded, “Significantly, the consumption of green leafy vegetables and fruits is consistent with these criteria.”
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Later on we look at cooking tips that keep oil use to a minimum. Happily, foods rich in antioxidants also tend to be very low in fat; broccoli, spinach, carrots, and other vegetables are loaded with beta-carotene and vitamin C, but are extremely low in fat. Beans and grains contain vitamin E, and are also very low in fat.

Another way to reduce your body’s production of free radicals is to watch your iron intake. Yes, after decades of popularity in the lay literature, iron’s reputation has started to erode. While everyone knows that we need iron to carry oxygen in the blood, few people are aware that, in excess, iron is actually a catalyst for the damage caused by oxygen. Just as iron and oxygen work together in the form of oxidation we recognize as rust, something similar happens within the body. Iron encourages the formation of free radicals and their damaging effects. Other metals, including copper and
aluminum, have also come under scrutiny for their complicity in free-radical damage.

Dr. Randall B. Lauffer is a biochemist at Harvard University. His book
Iron Balance
shows that iron can be like a detonator in a munitions warehouse.
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“Iron is a key component of the free radical theory of disease,” Dr. Lauffer said. “This was discovered some time ago, and as we have learned more over the years, we have found that iron sort of sits right in the center of all that chemistry.” Iron catalyzes the formation of free radicals, which then damage the tissue around them. Do we have lots of extra iron in our bodies? Unfortunately, the answer is yes. Men accumulate iron throughout adulthood. For most women, iron accumulation becomes a problem only after menstruation ceases.

“In general, as you age, you accumulate iron in your body,” according to Dr. Lauffer. “Your body is really a sort of dead end for iron. There’s no way to get rid of it in a regulated fashion. We can always get rid of extra sodium if you eat too many potato chips. But with iron, there’s really no way to get rid of it. It stays in your body. Most men have 1,000 to 2,000 extra milligrams of iron in their bodies, and that’s iron that they’re not using. It’s just waiting to cause trouble.”

Trouble is an understatement. As you will see in later chapters, iron-catalyzed free-radical damage is now thought to be the spark that can set off both heart disease and cancer, in addition to aggravating aging processes.

So where are we getting all this troublesome iron? From meat, first of all. Meat contains a form of iron that is absorbed a bit more easily than iron from vegetables. This used to be thought of as an advantage, but it is now known that more people get into trouble because of iron overload than iron deficiency. The meat-based diets that are routine in Western countries contribute a huge load of a perfect catalyst for free-radical formation. Vegetables, beans, and grains do contain iron, but the body is better able to limit absorption from these sources.