Vitamin A. See Beta carotene.
Beta Carotene. Converted into vitamin A in your body. It, along with vitamins C and E, is an antioxidant, which neutralizes free radicals. Free radicals may contribute to heart disease and cancer.
Several well-designed studies found pills no protection and two studies found increased risk of lung cancer in smokers. A six-month study in ferrets, which process this carotenoid (see carotenoids) much as humans do, indicates that excess beta carotene oxidizes, producing toxic metabolites. In the lung, beta carotene's metabolites destroyed retinoic acid, a vitamin-derived compound that suppresses cancer growth. The metabolites also activated a protein that spurs cell division. While the untreated ferrets had healthy lungs, those exposed to the supplements underwent precancerous changes. The lung damage was most prevalent in the animals who were also exposed to smoke. (Science News, February 20, 1999)
In a 1985 study, subjects who ate the most green and yellow vegetables (which are high in carotenoids) had one-third the death rate from cancer. However, carrots, which are extremely high in beta carotene, were not linked to a reduced risk. A 1989 study indicated that it is not beta carotene alone that has the protective effect, but from the combined effects of several protective agents in vegetables, some of which may not yet be identified. (2) (3) (4)
The B vitamins. Although there are 8 different B vitamins, they all have in common the function of breaking down fats and/or amino acids into carbohydrates and/or using the same for energy. Each has additional functions as described below.
B1 (thiamine) also helps maintain a healty nervous system. B2 (riboflavin) is also critical for production of hormones and formation of red blood cells. B3 (niacin) also is essential to the nervous system, improves circulation, and may be helpful in maintaining healthy cholesterol levels and regulating blood sugar. Niacin lowers low density lipoprotein (LDL) cholesterol (the bad kind) and triglycerides and raises high density lipoprotein (HDL) cholesterol (the good kind). However, side effects include flushing, headaches, cramps, and nausea. B5 (pantothemic acid) aids in formation of hormones affecting stress and infection. It supports the adrenal glands, digestive tract, and immune system. Crucial for the utilization of other vitamins. Aids in the formation of hormones affecting stress and infections. B6 (pyroxidine) may boost immunity in the elderly. Necessary for formation of prostaglandins and proper absorption of B12. B12 (cobalamin) is necessary for development of red blood cells and normal functioning of the nervous system. Biotin (B7), as with the other B vitamins, is essential for manufacture and breakdown of fats, amino acids and carbohydrates. It works synergistically with B9.
B9 (folic acid [folate, folacin]) is important in the snythesis of DNA, normal growth, and protein metabolism. It's involved in the production of neurotransmitters, such as serotonin, which regulate mood, sleep, and appetite. Aids in the prevention of anemia. Helps prevent bina spifida in new births, prevents cervical cancer, and linked to possible heart benefits. Two recent studies found that taking a daily multi-vitamin with folic acid could reduce the risk of colon cancer by as much as 75%. B6 and B12 work synergistically with B9. B12 (cobalamin) helps iron absorption and works with B9 for healthy blood cells and strong nerve cells.
Men with relatively low levels of B6, B12, and folate did not perform as well on some cognitive testing. B6, B12, and folate lower homocysteine levels, which is linked to arteriosclerosis. Homocysteine is a metabolite of the amino acid methionine, present in all proteins, but especially abundant in animal sources, such as meat, eggs, and milk. Vitamin B12 and folic acid convert homocysteine back to methionine. Vitamin B6 protects arteries by converting homocysteine to cysteine and other compounds that are excreted in the urine. Current thinking of the mechanism by which homocysteine causes arteriosclerosis is that a buildup of homocysteine leads to overproduction of a highly reactive form that causes LDL to become aggregated. (3) (20) (21) (22) (23) (24) (29)
The ongoing Framingham Offspring Study has demonstrated that supplements of B-12 work better than meat, poultry, or fish. Possible reasons are that cooking may destroy some and the way it is bound to protein in meats may make it less available. (Nutrition Action Health Letter, April 2000)
The B vitamins (except for B12) are found in greens, beans and legumes, whole grains, brewer's yeast, and wheat germ. B5, B6, and B7 are also found in nuts. B12 is found in animal products, cheddar cheese, cottage cheese, and miso (fermented soybeans).
Folic acid, the form of vitamin B9 found in pills, is more bioavailable than folate, the kind found naturally in vegetables. It is also difficult to eat 400 micrograms, the quantity in one multivitamin pill. (Harvard Health Letter, November 1999)
Vitamin C. Another antioxidant, shown to help prevent cancer and cardiac problems. May help strengthen resistance to viral infections and act as a mild antihistamine to help relieve cold symptoms. Healthy people in their 60s and older who had the highest blood levels of vitamin C and beta carotene scored higher on memory tasks.
Patients with documented exercise induced asthma were involved in a study in Israel. They were given either two grams of vitamin C or a placebo one hour before a 7-minute treadmill session. About half had improvement in asthmatic symptoms with the vitamin and one gram per day during the next two weeks continued to provide a protective effect.
Accumulating research has shown the protection of the antioxidants against heart disease, cancer, and other chronic disorders. However, under certain circumstances, they can cause some of the cellular damage they can protect against. A small English study of thirty people who took 500 mg of vitamin C daily for six weeks showed signs of genetic damage, presumably the result of free radicals created by vitamin C. However, leading scientists have pointed out serious flaws in the study. Dr. Bruce Ames, an expert in antioxidant research, noted that the researchers themselves may have created the damage when they ground up the cells to examine the DNA. (25)
According to a small study in the December 11, 1999, Lancet, 39 volunteers with moderately high blood pressure, the vitamin C group’s systolic pressure dropped by about 13 points and diastolic pressure 8 points.
Health Gazette, December 1999, states that vitamins C and E depress sperm motility, impairing fertility.
Vitamin C is an important one to me. I've taken daily megadoses for almost 30 years. It has helped alleviate my cold symptoms. Years ago Consumer Reports ran an article stating that there was no evidence of the efficacy of over 60 mg., the RDA. They now have ventured a little off that ultra-orthodox stand. The following is a summary from Consumer Reports on Health, November, 1998. A NIH study showed that high doses of vitamin C are "generally useless, since the body absorbs only a limited amount." The study consisted of 7 young men living in a hospital for 4 to 6 months, where they were fed a controlled diet that supplied all necessary nutrients except vitamin C. After their bodies were depleted of vitamin C, they progressively took larger daily doses, up to 2500 mg. Blood levels rose from 30% to 91% at 400 mg and total saturation at 1,000 mg. In addition, observation research suggests that vitamin C may provide protection against cancer, especially stomach cancer, due to its ability to fight oxidation, where the ulcer bacterium produces free radicals. Also, vitamin C helps neutralize nitrates, a carcinogen. Oxidation can damage both the retina and the lens of the eye. Both contain vitamin C and other antioxidants; hence, the formula known as Ocuvites and other formulations containing antioxidants.
The article points out that excess amounts can cause flatulence and diarrhea. In my experience, when my cold symptoms have been severe, I take sufficient amounts until I get diarrhea and then I back off. A small price to pay. The article further states that high does "theoretically could increase the risk of kidney stones in susceptible individuals." It does not state of even one incident of that occurring. In my readings, it appears oxalate can precipitate kidney stones, but not vitamin C. The article concludes that although 60 mg. will prevent scurvy (it is, after all, called ascorbic acid), eating the recommended daily servings of fruits and vegetables will supply from 200 to 350 mg, which should almost completely saturate the blood "--and may help ward off coronary disease, cancer, cataracts, and possibly arthritis, asthma, cognitive impairments and macular degeneration."
Recently investigators at the U. of Southern California, LA, monitored people who regularly swallowed vitamin C pills. After one year, the C takers had more thickening of their artery walls than those who didn’t take the supplement. 573 healthy middle-aged people were involved for an 18-month period. The summary of the study provides incomplete data and leaves many crucial questions unanswered. Further, this was a single study, and not a clinical trial. Tufts U. Health & Nutrition Letter, April 2000, did not provide any details of the study, but warned against supplements. U.ofCal, Berkeley, Wellness Letter, May 2000, did, and that newsletter continues to recommend a diet rich in vitamin C, as well as a daily supplement of 250 to 500 mg. daily. And if you take C, take E supplements, too, since they work together. The RDA was raised, but just from 60 mg to 75 mg for women and 90 mg for men. The upper limit is 2,000 mg. Higher amounts can cause diarrhea.
Researchers at the U.of California made the following finding after looking at data n more than 13,000 men and women: gallbladder disease was significantly more common among women who had relatively low levels of vitamin C in their blood. (Tufts U., Health & Nutrition Letter, May 2000)
Vitamin C is also essential to some important enzyme functions that the body needs to make collagen and norepinephrine, a key neurotransmitter. In a trial of 442 subjects aged 65-94, high blood concentrations of vitamin C and beta-carotene were associated with better memory performance. (Harvard Health Letter, August 2000)
Vitamin D and calcium. In 1994 the RDA for calcium was increased from 800 mg to 1500 mg for those over 65. (Similar increases for others have been instituted since then.) As you age, your intestine absorbs less vitamin D, which helps the body absorb calcium and deposit the mineral in your bones. Also as you age, your ability to synthesize the vitamin from sunlight diminishes. Twice the RDA in an 8-year study of more than 500 people found that knee osteoarthritis can be contained. (3) (26)
Vitamin D, being able to be made in the body, is a hormone. It helps the body utilize calcium and phosphorus and builds bones and teeth. It appears to have a beneficial effect on the immune system and a recent study and analysis of statistics indicate that it reduces the risk of breast cancer. Some test tube studies have shown that it inhibits the growth of cancer cells, including those in the breast and prostate. (U.of Cal, Berkeley, Wellness Letter, December, 1998.)
Vitamin E. Eight related compounds, four of which are tocopherols (alpha, beta, gamma, and delta) and four others are tocotrienols. A potent antioxidant that attaches to LDL cholesterol and prevents damage from free radicals. Vitamin E (found in nuts and oils) and vitamin C forestall losses in cognitive functioning in one small study. (3) (20)
In a Finnish trial of nearly 30,000 male smokers tracked for 5 - 8 years, vitamin E supplements did not reduce the risk of heart disease, but the dose of vitamin E was small, 50 IU daily. A British study used 400 to 800 IU among 2,002 men and women with clogged arteries and showed a large benefit for E.
Many studies have indicated that vitamin E reduces damage to arteries and heart problems. Two large studies from Harvard University, in particular, indicated that 100 units of E a day is effective for that. Known as the Nurses’ Health Study and the Health Professionals Follow-up Study, the research efforts were extensive, with conclusions based on many years’ worth of diet questionnaires from more than 100,000 people. However, studies in which people choose whether to take supplements have built-in confounding factors. Those people tend to e more health-conscious, smoke less, exercise more, stay at a lower weight, and eat a heart-healthy diet.
A new, highly regarded study (The Heart Outcomes Prevention Evaluation study, or HOPE) now says that vitamin E doesn’t appear to provide any protection against heart disease. This study followed 9,500 people age 55 or older who were at high risk for heart problems. For nearly five years, half the group was given 400 IU daily, while the other half took a placebo. There were no differences between the groups.
This latest study, however, is not the last word. The people in the HOPE study already had heart disease and other risk factors. So, presently the studies indicate that vitamin E helps those who have no heart risk factors or those who are in only the early stages of disease. (Tufts U., Health & Nutrition Letter, March 2000)
Not only is vitamin E a powerful antioxidant, it is especially active in cell membranes. Since the membranes of brain cells are loaded with polyunsaturated fatty acids, they are prone to oxygen free radical damage. (Harvard Health Letter, August 2000) A study published in the April 27, 1997, issue of the New England Journal of Medicine suggested that vitamin E modestly slowed the progress of Alzheimer's disease.
Tocotrienols, derived from rice bran, seem to lower blood fats by reducing circulating levels of a liver enzyme the body uses to make cholesterol. Several small studies have found impressive improvements. The brand name is Evolve.
Alpha tocopherol is the main type of E in the body. Natural E capsules contain d-alpha tocopherol and/or mixed tocopherols. Synthetic capsules are dl-alpha tocopherol, a slightly different molecular structure. Recent studies show that natural E is not only better absorbed, but also better retained in the body. Supplements are measured in international units (IU), which represent vitamin E activity in animal tests. (UofCal., Berkeley Wellness Letter, September 1999)
Health Gazette, December 1999, reported that it impairs sperm motility, impairing fertility.
The d-alpha tocopherol form of Vitamin E is the one vitamin whose natural form is better than the synthesized form (dl-alpha tocopherol). It appears to be slightly better retained and used by the body. (Nutrition Action Health Letter, April 2000) The RDA was raised to 22 IU or 15 mg. The upper limit is 1500 IU or 1,000 mg. Higher amounts increase the risk for bleeddng.
Vitamin K. Found in greens and necessary for blood clotting and strong bones. It helps keep bones strong by allowing a specific bone protein, osteocalcin, to undergo a chemical alteration that then lets it take its place in the body's skeletal structure. It is also essential for blood clotting. Various lines of research suggest that it may be crucial to nerve growth factors, highly specific proteins necessary for neurons (Harvard Health Letter, August 2000). Beneficial intestinal bacterial make much Vitamin K.
Potassium. Potassium is necessary for muscle, including the heart, functioning. It helps maintain normal water balance. It is lost in sweat. A diet rich in potassium can help lower blood pressure, and a recent study suggests that it can cut the risk of stroke.
Protein. Some studies suggest that active people may need more protein than those inactive, but the average American eats twice the Recommended Dietary Allowance. (Tennis USTA, December, 1998.) Exercising for one hour depletes 30 grams of protein, which should be replaced. (Fitness Swimmer, January/February 1999.)
Zinc. Although a zinc deficiency can weaken the immune system, studies have been inconsistent in showing that it could reduce severity of cold symptoms and increase immune responses. Six recent trials failed to find a clear benefit against the cold. Megadoses can interfere with iron and copper absorption, lower HDL cholesterol, impair blood cell formation, and depress the immune system. Side effects include nausea, mouth irritations, and mouth sores. (27) (28) Like lead, megadoses may slowly damage the kidneys and peripheral nerves (causing weakness, muscle wasting, impaired sensation, and possibly dementia). One of the first toxic effects to be detected is anemia and a low white blood cell count, both of which are adverse effects of zinc upon the bone marrow (Health Gazette, December 1999).
Most Americans, however, have a low-zinc diet and zinc is also lost through sweat. A deficiency can weaken the immune system, retard muscle growth, slow the healing process, cause white spots on nails, dull the sense of taste and smell, cause hair loss, and cause lethargy. Zinc may also help prevent or slow age-related macular degeneration. The National Eye Institute is undergoing a 7-year study to test this. (Remedy, Nov/Dec 1999.) Zinc is found in wheat germ, pumpkin seeds, brewer’s yeast, osyters, eggs, seafood and lean meats.
Zinc is essential for normal sexual development during male adolescence and for producing healthy sperm. Only two good studies have been done for sexual function, and they were inconsistent. (Nutrition Action, July/August 2000).
