Pumping immunity.

Money. It can't buy you love...or the ability to fight disease.

Good genes might buy you some time. But sooner or later your immune system will start to wind down.

And when it does, down goes your ability to withstand the viruses, the bacteria, the contaminants, and the cancer-causers that you once shrugged off so easily.

Is the decline inevitable? Nutrition Action's David Schardt asked five leading experts on nutrition and the immune system.

Their consensus: No. With the help of certain vitamins and minerals, many of us may be able to re-capture the immune systems we had when we were 20 years younger.

They explain how, in interviews beginning on page 5.

Q. How important is nutrition to a strong immune system?

Blumberg: It was only about 30 years ago that people even discovered that nutrition affected immune response. That was in studies of starving kids. When these children were given food, their immune systems improved. What we've now discovered is that improving the overall nutritional status in older people will perhaps improve their immune function.

Q: Is it ineuitable that our immune systems decline as we age? Blumberg: We always assumed that to be the case. You can expose a 1O-yearold and an 80-year-old to the same cold virus. The 1O-year-old is sick for a day and is back on his feet the next day. The 80-year-old--same strain, same virulence, same everything--is knocked out for a week and it takes two weeks to get better. But we've now found that many of these so-called age-related changes in immune function are not age-related at all. They have much more to do with your nutritional status.

Q: Does that mean these changes can be reversed?

Chandra: Yes. Assuming you have the genetic basis for a good immune system, some people whose immune systems are declining as they age may be able to restore them to younger potency with careful attention to diet and, perhaps, nutrient supplements.

Blumberg: I don't want to suggest that there is no such thing as an age-related decline in immune function. But the rate of that decline is much greater than it needs to be, because we can slow it down through nutritional inter- ventions.

Q: What's the evidence?

Blumberg: Dr. Chandra has just published what I think is a landmark study. He took about 100 middle-class Canadians over the age of 65. For one year he gave half the people a multi-vitamin-and-mineral supplement with extra vitamin E and beta-carotene, and half the people a placebo of just calcium and magnesium.

What he saw was astonishing. The group that took the supplement had half the number of colds, flus, and other infection-related illnesses. And, when study participants did get sick, the supplement group got better in half the time. (1)

Q: How dangerous are infections to the elderly?

Blumberg: They're the fourth leading cause of death in older people.

Q: Did the study show anything else?

Blumberg: Yes. That a supplement can strengthen the immunity you get from a flu vaccine. Older people are more susceptible to the flu than younger people, but they don't respond to flu shots as well. They don't maintain high enough antibody levels. The supplement raised those levels.

Q: How much extra vitamin E and beta-carotene did the supplement contain?

Chandra: It had 44 mg of vitamin E and 16 mg of beta-carotene. [For vitamin E, 1 mg is equivalent to I IU. For beta-carotene, every 3 mg are equivalent to 5,000 IU.--Ed]

Q: 50 antioxidants boost the immune system?

Blumberg: In another study, when we gave vitamin E supplements to healthy older people, we were able to boost a whole variety of immune responses. We used 800 IU a day, which is a pretty big dose, but this was a short-term study. We are currently looking at lower doses over a longer time period. The preliminary data are also quite positive.

Q: And vitamin C?

Chandra: A moderate excess of vitamin C, about 100 to 250 mg a day, does not really stimulate immunity to any large extent.

Q: What about beta-carotene?

Bendich: In a number of animal studies, several types of immune ceiis that are important in preventing the growth of cancer cells were enhanced with diets containing beta-carotene and other carotenoids.

Q: Does that apply to humans?

Bendich: Only a handful of studies have looked. They have shown, for example, that the number of beneficial natural killer cells was enhanced in a healthy elderly population taking 30 to 60 mg of beta-carotene daily for about two months. And in a justreleased study, beta-carotene had a positive effect on certain immune cells in HIV-infected individuals (see "Betacarotene and HIV," p.7).

Q: Could antioxidants explain why fruits and vegetables are linked to a lower risk of some cancers?

Blumberg: It's certainly possible. One of the most important systems for fighting cancer is the immune system.

Q: What about vitamin B-6?

Blumberg: A few well-done studies show that vitamin B-6 is a major contributor to immune responses. Its intake is quite low in elderly people. In a recent study, healthy people were put on diets that were deficient in B-6. Their immune responses were then followed as they were given B-6 at ever-increasing doses. When they received 3 mg a day, their responses started returning to where they had been before the study began.

Q: So the U.S. Recommended Daily Allowance (USRDA) of 2 mg a day wasn't enough?

Blumberg: That's right. It was inadequate to maintain optimal immune function. When they were give 50 mg a day-way above USRDA levels but still quite safe-tor replenish all their vitamin B-6 stores, their immune responses were boosted over the levels they had before they entered the study. [Some people may develop reversible neurological damage after taking as little as 100mg a day of B-6-Ed]

Q: They became "super-immune"?

Blumberg: We're not somehow making older persons' immune systems super-powerful. We're making them almost as strong as they used to be.

Q: Does iron affect the immune system?

Sherman: Decreased immunity and increased infection are associated with iron-deficiency anemia. I don't think there is any evidence that taking iron supplements is going to stimulate the normal immune response. They are only useful for curing a deficiency.

Q: What about zinc?

Cunningham-Rundles: Studies have shown that zinc has helped the immune systems of the elderly. That may be because zinc is essential for the functioning of thymic hormone, which is needed to produce mature T cells, a major part of the immune system.

Q: Many people consume less than the USRDA for zinc. Could that depress their immune systems?

Cunningham-Rundles: Yes. It's been documented in schoolchildren and women of childbearing age. But it hasn't been as well-documented in other people living active lives who eat marginal diets, which I think is extremely common.

When perfectly healthy people are put on diets that reduce their zinc levels to the low end of what is considered normal, they suddenly show a poor immune response. This is reversed when they receive zinc supplements or food that contains zinc. My conclusion is that the USRDA for zinc (15 mg a day) should be higher-- perhaps twice as high. But the research hasn't been done yet. You'd probably need a supplement to get that much.

Chandra: It's important to point out that very large doses of zinc, on the order of 300 mg a day, may be detrimental to the immune system.

Q: Are there any other nutrients that depress the immune system?

Chandra: Very large amounts of vitamin A--not beta-carotene---and selenium also may.

Q: And fat?

Cunningham-Rundles: Absolutely. An interesting example is the case of lntralipid, a special fat developed for feeding malnourished patients through tubes. A surgeon ln England prescribed Intralipid for his cancer patients, thinking it would help them regain weight and muscle. But he found, to his horror, that it actually helped their cancers spread. One possible explanation is that the fat suppressed the components of the patients' immune systems that were helping to hold their tumors in check.

Q: Could the amount of fat in the typical American diet--about 35% to 40% of calories-cause damage?

Cunningham-Rundles:

Right now we don't have the answer. But all indications are that it does.

Q: So how much of which nutrients should people consume?

Blumberg: We're still trying to define the optima1 intake of antioxidants to enhance immune response.

Dr. Chandra's work indicates that it's probably at least three to four times the USRDA for beta-carotene and vitamin E, when mixed with all the other vitamins and minerals.

Bendich: I don't think we can tell people what's enough. They shouldn't ever do anything based on one study. But there is a growing body of literature on betacarotene and the immune system. All of the National Cancer Institute's cancer chemoprevention studies have used between 15 and 50 mg a day with no adverse effects reported.

Q: Can people get enough antioxidants from food?

Blumberg: I doubt that you can get enough vitamin E through even a healthy diet, unless you want to drink too much oil, salad dressing, or other fatty foods like that. But vitamin C and beta-carotene you probably can get. The problem, of course, is that people don't.

Bendich: I think it's possible to obtain 30 mg of beta-carotene a day from the diet, but you have to choose your food wisely (see "Beta Foods").

Chandra: I think that people should at least attempt to attain the right levels through diet. I'm not sure if this will be feasible for all of the elderly, because of their problems with chewing, digestion, and absorption. But it certainly should be the first line of action. If it's not possible, then people should consider a nutritional supplement.

Q: Are supplements the answer to a declining immune system?

Blumberg: People have to change their lifestyles and their diets. But we cannot ignore the compelling data that supplementation is an effective and immediate way to begin to address the problem of inadequate nutritional status associated in older adults with impaired immune responses.

Should people take a multi-vitamin and multi-mineral supplement and extra vitamin E and beta-carotene? The data isn't clear yet. However, there is no risk involved, and l think if people want to they can do so in a logical, rational, and justified way.

1. Lancet 340:1124, 1992.

Beta Foods

How much food would you have to eat to get 30 mg [50,000 IU] of betacarotene?

Any of these would do it:

* 1 cup of cooked sweet potatoes

* 3 medium carrots

* 3 cantaloupes

* 14 cups of cooked collard greens, or

* 23 cups of cooked broccoli.

Source: USDA Handbook 8

Beta-carotene and HIV

Since beta-carotene may give the immune system a boost, can it help prevent people who are infected with the HIV virus (which causes AIDS) from getting sick? Maybe.

When 21 HIV-positive people were given 180 mg [300,000 IU] ofbetacarotene even/day for four weeks, several indicators of their "helper" T cell activity increased significantly. When the people were given a look-alike-butinactive placebo for four weeks, the indicators dropped. "Helper"T cells are the primary target of the HIV virus, and the body's ability to fight infections diminishes as their levels drop.

But Gregg O. Coodley, the physician who conducted the study at the Oregon Health Sciences University in Portland, points out that only a small number of patients were followed for a brief time.

"We still don't know whether, over time, the effect of beta-carotene would disappear or increase," he says.

"I've told my own patients that it's too early to definitely go on beta-carotene. But it's also true that it probably wouldn't hurt them, either."

[180 mg is a very high dose of beta-carotene, but it has been given to people with certain skin conditions with no adverse effect.--Ed]