Can vitamins cure an infection or prevent one from taking hold? Sadly, the answer is No. However, extra doses of certain vitamins do seem to reduce the severity of some infections. And there's no question that an outright vitamin deficiency is an invitation to disease.
As we all know in this era of AIDS and HIV, a robust immune system is all that stands between us and perpetual infection. And the nutrients in our diet have a definite impact on the status of the system. This was firmly established long ago, when doctors noticed that under-nourished patients were less able to fight infection. More recently, many experts have come to believe that the lowered immunity that accompanies old age is to some extent a result of poor nutrition, rather than inevitable decline.
Nutritional Mainstays of Immunity
Maintaining your immune system in peak condition may require more than the official Recommended Daily Allowances (now called Daily Values)—or so some studies suggest. RDAs were established to prevent deficiency diseases, not to help the immune system; and these values have rarely been changed. On the other hand, too much of certain nutrients can actually hamper immunity.
To be honest, this is an area of science where confusion still reigns. The immune system is complex and resilient. In some people, a vitamin deficiency may have no practical effect at all. In others, extra vitamins and other nutrients may prove to be helpful. Amid all the uncertainty, however, a few vitamins and minerals stand out. Here's a look at those that seem especially important for a strong, healthy immune system.
Vitamin A
A deficiency can increase your vulnerability to infection, but overdosing is harmful. Getting less than the government recommendation of 5,000 International Units of vitamin A can:
Reduce the size of the thymus, a gland that makes the disease-fighting white blood cells called lymphocytes Shrink the number of lymphocytes Reduce production of antibodies that fight infection Reduce the ability of the respiratory tract to push bacteria out of the system Carotenoids such as beta-carotene are forms of vitamin A. They help regulate three types of immune cells: T and B lymphocytes, natural killer cells, and macrophages.
We do not yet know whether people who get too little vitamin A or beta-carotene actually become sick more easily or whether their illnesses are more serious. Some studies indicate that if you develop a bad case of measles or pneumonia, or have a long-lasting fever, you need more vitamin A than the Food and Drug Administration (FDA) recommends. Conversely, there is evidence that the body reduces vitamin A circulation as part of its response to infection. If this is true, increasing vitamin A levels during infection would be counterproductive, as long as the person had an adequate amount before getting sick.
In any case, several studies in developing countries have found that giving vitamin A supplements to children with measles significantly reduced their chance of dying. Most of these children were vitamin-A deficient before they became ill. In at least one study, children receiving vitamin A had fewer measles symptoms than those who didn't take the vitamin.
There is some evidence that supplemental vitamin A can increase the immune response of cancer patients, as well—although extremely high doses seem to suppress it. Too much beta-carotene also may impair the immune system. A study of smokers conducted in Finland found a slight FACE="I Times Italic" >increase in lung cancer among the smokers who took a daily 20-milligram beta-carotene supplement. Based on this finding, some nutritional authorities now recommend limiting your beta-carotene intake to the amount found in a standard multivitamin tablet.
Vitamin A is fat-soluble. Unlike water soluble vitamins, it is stored in your body fat, where it can build up to dangerous levels. Taking too much of it can cause headaches, nausea, and possible liver problems.
Vitamin B complex
Deficiencies of the B vitamins definitely lower your resistance. Deficiencies of B2, B6, B12, folate, and pantothenic acid have the greatest impact. A deficiency of biotin or thiamine is less significant. Oral contraceptives tend to reduce the supply of several B vitamins, including B6. Eating foods rich in the B vitamins should be enough to overcome this effect, however.
Although most people get sufficient vitamin B12 in their food, between 10 and 30 percent of older adults lose their ability to adequately absorb the naturally-occurring form of B12. Therefore, the Institute of Medicine recommends that adults over age 50 meet most of their recommended daily intake (2.4 micrograms) with synthetic B12 from fortified foods or vitamin supplements.
Vitamin C
The craze over vitamin C's power to prevent and treat colds started with the Nobel Prize-winning chemist Linus Pauling's 1970 book Vitamin C and the Common Cold. Pauling advised taking 3,200 to 12,000 milligrams per day, far higher than conventional standards. The latest recommendation from the Institute of Medicine is 75 milligrams per day for women and 90 for men, with an extra 35 milligrams daily for smokers, who suffer higher levels of oxidative stress and cellular damage. This is a far cry from Pauling's original proposals. And studies testing Pauling's cold theory indicate that vitamin C probably does not prevent colds but may make them milder and shorten their duration.
Key Players In Your Immune System
Antibodies —elements of the immune system targeted to specific invaders that you have been exposed to before. Macrophages —cells that kill bacteria by surrounding and, in effect, eating them. Lymphocytes —infection-fighting white blood cells. Lymphocytes play a role in making antibodies. T-cells — a type of lymphocyte attacked by HIV. Thymus —the gland where cells mature into lymphocytes. Neutrophils —compose about 75 percent of circulating white blood cells. Interleukin-2 — A hormone that promotes growth in the number and power of T-cells. How does vitamin C affect immunity? Vitamin C has been proven to boost the bacteria-killing ability of certain immune cells called macrophages and neutrophils. Some authorities believe that vitamin C also stimulates production of interferon, an important chemical in the immune system, and that it improves the thymus gland's ability to make infection-fighting lymphocytes, a type of white blood cell.
How much Vitamin C is enough? In a number of studies, megadoses have delivered only minimal benefits, producing at best minor symptomatic relief. In one study, doses of less than 100 milligrams daily were said to achieve the same results as 1 to 2 grams per day.
Other studies, however, do bear out the protective power of higher doses. One well-controlled study showed that, when volunteers were deliberately infected with a cold-causing virus, those taking 500 milligrams of vitamin C four times a day (that's a total of 2,000 milligrams or 2 grams per day) had symptoms half as severe as those taking a dummy pill instead. Some nutritionists now recommend taking 750 milligrams daily during the cold season as a preventive measure, and raising that amount to 1 gram (1,000 milligrams) at the first sign of cold symptoms. If you get a cold, they advise taking 500 milligrams every two-and-a-half hours during the daytime and 1 gram of time-released vitamin C at bedtime.
Can too much hurt you? Unlike vitamins that remain in your body fat, vitamin C is water soluble. Because excess amounts are rapidly flushed from the body, the danger of overdosing is minimal. Large doses, however, can lead to diarrhea, gas, and heartburn. Taking 5 to 10 grams a day can cause nausea and vomiting.
People with certain health problems may experience additional side effects:
High vitamin C intake can reduce the effect of warfarin, a medication used to thin the blood, and of certain drugs used to treat infections of the urinary tract. If you take these drugs you should not supplement your diet with megadoses of vitamin C. Because it is an acid, vitamin C may irritate stomach ulcers. If you have problems storing iron, vitamin C can cause serious problems by releasing too much iron into the blood. In people with genetic blood diseases such as sickle-cell anemia or thalassemia, too much vitamin C can make red blood cells self-destruct. Animal studies have also shown that megadoses can lead to spontaneous abortion. Anyone taking megadoses of vitamin C over a long time can become dependent on it. The body may respond to uninterrupted high levels by activating an enzyme to destroy the vitamin. If you then cut your dosage too quickly, you may go through a withdrawal process that includes signs of vitamin C deficiency.
What to do. The consensus today is to take no more than 1,000 milligrams of vitamin C per day. Taking it in small doses with meals rather than all at one time increases the amount that your body absorbs. Always swallow the tablet immediately; chewing vitamin C can erode tooth enamel. Tell your doctor if you take 1,000 milligrams or more daily. Megadoses may affect the results of blood sugar checks for diabetes, and of other medical tests.
If you choose to exceed the 1,000-milligram-per day level, remember that the Institute of Medicine has declared 2,000 milligrams per day to be the "tolerable upper intake level." Regular doses higher than that amount are liable to cause side effects in a significant number of people.
Vitamin E
There is renewed interest in vitamin E lately due to its antioxidant effect. As an immunity-booster, however, its value is debatable. In the past, some experts have recommended taking 3 to 4 times the Recommended Daily Allowance to keep the immune system at its peak. However, megadoses of vitamin E have been found to suppress the function of B cells, an important component of the immune system. The current daily intake recommendation from the Institute of Medicine is 15 milligrams of the form of vitamin E known as alpha-tocopherol. This level is equivalent to 22 International Units of d-alpha- tocopherol (natural source) vitamin E or 33 IUs of the synthetic form (dl-alpha-tocopherol). Nuts, seeds, liver, leafy green vegetables, and some vegetable oils are all sources of d-alpha-tocopherol.
The Institute's "tolerable upper intake level" is 1,000 milligrams per day for adults, a level that can be reached only by taking supplements. That amount translates into 1,500 International Units of natural- source vitamin E supplements or 1,100 International Units of the synthetic version. Consuming greater amounts heightens the risk of bleeding, since this nutrient acts as a blood-thinner at high levels.
Iron
Many Americans lack sufficient amounts of this important mineral. Menstruating women, for example, lose iron with the blood in their periods every month. Without enough iron, the number of antibodies in the immune system are reduced, and the system's natural killer cells, neutrophils, and macrophages are unable to kill bacteria as effectively as they should. Iron deficiency may also lower both the number of white blood cells and their ability to fight infection.
Too much iron however, may be as dangerous as too little. Iron overload interferes with immune responses and reduces the number of cells that grow into lymphocytes. It also can produce an iron storage disease called hemosiderosis. The latest recommendation from the Institute of Medicine is 8 milligrams a day for men and postmenopausal women, and 18 milligrams a day for women in their childbearing years. There is no evidence that supplementing the diet with higher doses can "soup up" your immune response. You should take iron supplements only to correct a deficiency.
Because bacteria need iron to grow, some authorities have argued that iron deficiency actually reduces risk of infection. Most human studies do not support this conclusion. Reducing iron offers no protection against disease, and correcting the deficiency does not increase the number or seriousness of infections.
L-arginine
Imbalances in amino acids, the building blocks of proteins, can impair immune response. In animals, L- arginine stimulates the adult immune system and reduces the growth and spread of experimentally induced tumors. In studies with people, use of this amino acid has led to an increase in the number of lymphocytes and has shortened hospital stays after major operations. Some evidence suggests that large doses of L-arginine could help in treating AIDS and cancer. However, researchers want more information before recommending L-arginine supplementation.
Protein
Severe protein insufficiency reduces the size, weight, and function of the thymus, a small organ located in the chest. Because the thymus makes the white blood cells that produce antibodies and kill invading microorganisms, shrinkage of the gland decreases the body's ability to fight infection. Protein deficiency is uncommon in this country except among the poor, those with certain illnesses, and elderly people who may find it too difficult or expensive to prepare nutritious meals. In fact, because most of us eat more protein than we need, deficiency is rarely to blame when the immune system malfunctions.
Selenium
Although a lack of selenium is linked to an increased risk of cancer, its role in fighting infection is unclear. When levels are too low, the body cannot produce sufficient antibodies to combat illness. (Vitamin E reverses this effect.) A moderate increase in intake has been found to boost immune response in animal tests; but an overdose can do the opposite. The government recommends a daily intake of 55 micrograms for women and 70 micrograms for men; doses above 400 micrograms per day are considered unsafe. The risk of a toxic reaction increases with the size of dosage. Warning signs of overdose are hair loss and fingernail and toenail damage.
Zinc
The Institute of Medicine's current recommendation for zinc is a daily intake of 8 milligrams for women and 11 milligrams for men. Consuming less hampers the immune system in several ways:
Shrinks the size of the thymus, where the disease-fighting white blood cells called lymphocytes are made. Reduces the number of lymphocytes Slows the production of lymphocytes Impairs the function of lymphocytes and the germ-killing cells called macrophages Decreases antibody response Prevents wounds from healing properly Zinc deficiencies can reduce immunity in both school-age children and women of childbearing age. There is also some evidence that healthy people consuming low-normal levels of zinc have diminished immune response.
According to some estimates, fewer than 50 percent of Americans get an adequate amount of zinc. Among those most likely to be deficient are the elderly, dieters, alcoholics, pregnant women, infants, and people with injuries, burns, or infections. Zinc is found in animal-derived foods such as meat, eggs, and cheese, and restoring zinc-rich foods to your diet can bring the immune system back to par within two weeks.
When it comes to zinc supplements, however, more is definitely not better. In fact, exceeding the RDA even slightly may be harmful. Overdosage (300 milligrams a day) may actually impair immunity, while doses of 90 to 100 milligrams per day taken over a long period of time can reduce immunity, lower levels of "good" HDL cholesterol, and produce anemia.
What to Eat—and Not Eat—When You're Sick
The old saying about starving a fever was right. Starving a fever isn't much of a deprivation, either, since illness usually ruins your appetite. In fact, it appears that loss of appetite is the body's way of saying that you should eat less while it battles foreign microorganisms. As part of this strategy, the body usually withdraws iron, zinc, and other nutrients from the bloodstream and stores them in the liver, thymus, and bone marrow so bacteria can't snap them up.
Well-nourished, otherwise healthy adults can deal with the nutritional depletion that results from infection. But extra care is needed for children, the elderly, and anybody who is sick more than about five days or loses five percent of their weight. A vitamin or mineral supplement or a liquid nutritional supplement taken under a doctor's supervision may be helpful. If you lose a great deal of weight during an infection, you may require extra protein to nourish your immune system.
When your fever breaks, drink lots of water and other fluids—especially citrus juice—to replace the fluid you have lost. Also, eat grapes, juicy fruits, milk shakes, broth, and whole grain breads. They can help replace the missing nutrients. Citrus and other fruit juices and juicy fruits are especially good sources of potassium.
Feeding a cold is another piece of folklore that turns out to be correct. Hot, spicy foods, such as chili peppers, horseradish, black and red pepper, garlic, and pepper sauce may stimulate mucus flow and relieve symptoms of asthma, bronchitis, sinus trouble, and colds. However, people with asthma who are taking theophylline should not feed their cold charcoal-broiled meat, broccoli, or cabbage. Research at Rockefeller University in New York has shown that protein, hydrocarbons on charcoal-broiled meat, and chemicals found in cruciferous vegetables such as broccoli can speed up liver function and rush some drugs, including theophylline, out of the system before they've done their job.
Science also is finding evidence to support the use of chicken soup as a cold remedy. In the late 1970s, researchers learned that hot liquids—including chicken soup—break up congestion, relieve sore throat, and increase the flow of nasal secretions. This may help block cold viruses from infiltrating the body. Inhaling the vapors of hot liquid through the nose seems to do the trick. In 1993, Dr. Stephen Rennard of the University of Nebraska found that a much-diluted version of chicken soup made from his wife's family recipe was capable of reducing the inflammation that causes many cold symptoms, such as a sore throat and production of phlegm. The hundreds of biologically active compounds found in the vegetables used in the soup may be the "good guys." Although soup doesn't cure the underlying problem, neither do any of the drug store remedies.
Extra Vitamins for Older Adults?
The elderly get sick more easily, take longer to recover, and are more likely to develop life-threatening illnesses. In fact, infections are the fourth leading cause of death in the elderly. Although the immune system declines naturally with age, an insufficient diet can make matters worse.
Several surveys have shown that almost one-third of apparently healthy elderly people get too little iron, zinc, beta carotene, and vitamins B6 and C. Correcting these deficiencies with supplements has successfully strengthened immune response. Although heredity also may play a role in immune system decline, some researchers now feel that reduced immunity need not inevitably accompany aging. Indeed, 20 to 25 percent of older people maintain immune systems as vigorous as those of younger adults even into their 70s and 80s.
Ideally, the elderly should build up their immune systems by eating more fruits, vegetables, and other nutrient-rich foods. Unfortunately, however, those who have lost a spouse or live alone are often not motivated to fix healthy meals. Some senior citizens cannot get out to shop; others have lost their teeth or have other medical problems requiring special diets. Many take several prescription drugs, some of which may interfere with absorption of nutrients from food. (See "Foods to Watch Out for When Taking Medication," for details.)
For all these reasons, extra vitamin and mineral supplements may be a good idea for some older people. The additional nutrients are not, of course, a guarantee against illness; and researchers feel that the evidence in their favor is not yet conclusive. Still, hints are accumulating that taking supplements above the Recommended Daily Allowance can indeed boost immune function in the elderly. Here are some of the specifics.
Vitamin E. A study of the effects of 200 milligrams of vitamin E daily on healthy older persons showed that the supplement enhanced immune function without any adverse effects. Further research confirmed that giving megadoses of vitamin E (around 1,000 International Units or more) to healthy older people for a short time boosted immune function. However, the research did not track the seniors' ability to avoid and fight infection over the long term, so the researchers say that further work is needed before they can recommend that older people routinely take vitamin E supplements in excess of the 30 International Unit RDA.
Vitamin B6. There is some evidence that extra vitamin B6 can give older immune systems a boost. In a study at Tufts University, a dosage of 50 milligrams a day (25 times the 2-milligram RDA) hiked immune response to that of much younger adults. However, there's a definite danger in large doses. Some people develop reversible nerve damage at doses of 100 milligrams per day. No conclusive research has been done in this area, so the wisest course is to stay relatively close to the official RDA.
Beta-carotene. A handful of studies have shown an increase in the number of natural killer cells in healthy elderly people taking 30 to 60 milligrams of beta-carotene daily for about 2 months.
Multivitamin and mineral supplements, with extra vitamin E and beta-carotene. One study of 95 people age 65 and older found that taking a vitamin E- and beta-carotene-rich multivitamin not only reduced infections, but also increased the protection afforded by flu shots—a vital consideration for older people, who are more likely to get sick from, and die of, the flu than are younger adults. Larger studies are needed to be sure that these findings are valid, however.
Zinc. In one recent study, people taking low doses of both zinc and selenium showed an increased resistance to respiratory tract infections. But beware of overdoing it. While the recommended amount of zinc (8 to 11 milligrams daily) can increase the number of T-cells in the immune systems of older people, larger doses (less than 10 times the RDA) can cause bloating, nausea, cramps, diarrhea, and fever. Even higher amounts can lead to bleeding and anemia.
HIV, AIDS, and Nutrition
Good nutrition does absolutely nothing to prevent HIV infection. The virus is transmitted by intimate sexual contact whether you have a balanced diet or not. However, there is some reason to believe that an enriched diet can slow the progression of the disease. And because AIDS is often accompanied by malnutrition, careful attention to diet is especially important.
Nutrition is a problem for several reasons. Lack of energy or motivation to prepare meals make people with HIV more likely to eat improperly. As HIV progresses, patients are prone to develop infections that cause diarrhea and make it more difficult for the body to absorb needed nutrients from the food they do manage to eat. And many drugs used to treat HIV and its complications can cause nausea, vomiting, or weight loss: Trimethoprim can lead to folic acid deficiency; pentamidine can cause low blood sugar. People with AIDS are also vulnerable to "AIDS-wasting syndrome," a condition which produces severe, life- threatening weight loss. This complication requires nutritional supplements and sometimes, medication.
Preliminary evidence suggests that supplementing a diet rich in fruits and vegetables with a multivitamin that includes iron, vitamin E, and riboflavin may, in some cases, delay the development of full-blown AIDS. In a 6-year study of 296 HIV-infected men, researchers found a 31 percent reduction in development of outright AIDS among those on a vitamin-rich diet—far from conclusive proof, but still encouraging.
Some smaller, shorter studies have evaluated effects of a single nutrient on people with HIV. One such study of 21 HIV patients produced an increase in the immune system's T-cell activity after 4 weeks of 180 milligrams of beta-carotene daily. This dose is very high, but has been given to persons with certain skin conditions without adverse effects. Iron, on the other hand, definitely should not be taken in large doses. It may cause dormant bacterial infections to re-emerge.
Going to Extremes
People who suffer from AIDS are often desperate. Many seek alternative therapies, including nutritionally based options. Here are some of the untested, nontraditional programs they are likely to encounter.
Megadoses of nutrients. Although large doses of vitamins A, C, E, B12 and both selenium and zinc are sometimes recommended to increase the number and activity of the immune system's T-cells, very high doses have not been proven effective, and may even be dangerous. Regular consumption of more than 50,000 IU a day of vitamin A (10 times the recommended amount) can be poisonous to the system. As little as 25 milligrams of zinc daily can cause nausea and impaired immune function.
Even routine daily use of one multivitamin pill has been associated with a longer delay in progression from HIV to AIDS, says Mary Romeyn, MD, a San Francisco internist and author of Nutrition and HIV: A New Model for Treatment. She recommends the following for all patients: a multivitamin, without extra iron, twice a day, a trace element supplement once a day, and an antioxidant supplement once a day. This approach will help prevent outright deficiencies, and offers a safe, supportive regimen that is easy and inexpensive, says Romeyn.
For those who want to do more, Romeyn suggests the following:
A multivitamin, without extra iron, twice a day A trace element supplement once a day A vitamin C supplement, 1,000 to 3,000 milligrams (as tolerated), once a day; or 3,000 to 6,000 milligrams (as tolerated), once a day during periods of active illness A vitamin E supplement (alpha tocopherol preferred), 800 to 1,200 units, once a day A beta-carotene supplement, 15 milligrams (with 25,000 units of vitamin A), twice a day A vitamin B stress complex supplement twice a day A magnesium supplement, 250 milligrams, twice a day A selenium supplement, 50 micrograms, one to four times a day. Dr. Berger's Immune Power Diet. This regimen is based on a 1985 book that blames poor health on "immune hypersensitivity" to common foods such as milk, wheat, corn, yeast, soy, sugar, and eggs. The diet has not been tested scientifically, and is too low in fat and calcium to be considered healthy.
AL 721. This product is made from soy or egg yolks, and consists of active lipids and lecithin. The Food and Drug Administration tested the preparation for use by HIV patients and found few side effects but no consistent benefit. In some studies, AL 721 increased body weight and levels of both "good" (HDL) and "bad" (LDL) cholesterol. While AL 721 may not help much, it probably can't hurt.
Macrobiotic diet. Based on Asian philosophy, this low fat, high fiber program is intended to improve health by restoring balance in the body. Up to 50 percent of the diet consists of whole grain cereals, 20 to 30 percent of fresh vegetables, 10 to 15 percent of cooked beans or seaweed, and 5 percent of miso (fermented soy paste) or tamari broth soup. Macrobiotic diets can cause protein deficiency and do not offer enough riboflavin, niacin, or calcium for adults.
Butylated hydroxytoluene (BHT). Assertions that this antioxidant food preservative kills HIV by attacking the outside coat of the virus are unfounded. The product also may not be safe.
Laetrile. Evidence indicates that treatment with this substance, originally intended to destroy a tumor enzyme in cancer patients, is not only ineffective but also potentially harmful. Proponents recommend laetrile as part of a regimen including a strict vegetarian diet that excludes milk and other animal products along with meat and vitamin supplements. This program may not supply enough calcium, iron, niacin, and vitamin B12, and may include too much thiamin, vitamin A, vitamin C, and zinc.
The Gerson method. Aimed at AIDS-induced cancers, this program includes an inadequate diet of unproven effectiveness. It restricts intake of all food except oatmeal and fresh fruits and vegetables, and advocates using enemas, especially coffee enemas, to create an environment hostile to cancerous cells.
The Kelley regime excludes meat, peanuts, and milk (in all forms except yogurt) in an effort to overcome a supposed pancreatic enzyme deficiency. It substitutes almonds for meat and recommends various supplements. Possible dangers of the diet include vitamin A toxicity, protein and calcium deficiencies, and fluid losses.
Getting More Nutrients Into the Diet
When getting enough food becomes a problem, the usual caloric no-no's become a recommended diet. Consider cooking with milk instead of water, buy canned fruit in heavy syrup, and eat more than three meals a day (snacking is fine). A doctor or nutritionist may recommend a liquid food supplement, such as Ensure or Sustacal. If lesions in the mouth make it painful to eat, try soft foods, such as poached eggs and ice cream.
Source: From the PDR® Family Guide to Nutrition and Health™
