Terms and Abbreviations to Know How to Use This Guide Arthritis Needs How Much is Too Much? Panel of Reviewers From the 2003 Guide: What About Multivitamins? Supplement Guide

Water-Soluble Vitamins
Be sure to get adequate amounts of the B vitamins, including folate, and vitamin C every day. During digestion, these vitamins are absorbed into the blood and transported around the body. The body uses them quickly, however, and excretes -- rather than stores -- what it doesn't need.

Vitamin B-1
Other names: Thiamine and thiamin.
Why: Converts glucose to energy; essential for normal functioning of the heart, brain, nervous system and muscles.
How much: RDA = 1.2 mg for men; 1.1 mg for women.
Too much: No known symptoms, but an allergic reaction may result in flushing, itching or swelling.
Too little: Deficiency is associated with abnormal carbohydrate metabolism. Prolonged deficiency can affect the nervous and cardiovascular systems.
Foods: All plant and animal foods contain thiamine, especially whole wheat, brown rice, fish and lentils. Enriched pasta, bread, cereals and rice.
Supplements: Multivitamins generally provide 100% or more of the DV.
Interactions: Research links long-term use of the diuretic furosemid (Lasix) to vitamin B-1 deficiency. Regular use of antacids also may interfere with thiamine's absorption.

Vitamin B-2
Other names: Riboflavin.
Why: Promotes healthy development; helps produce skin and red blood cells; helps convert glucose to energy.
How much: RDA = 1.3 mg daily for men; 1.1 mg daily for women.
Too much: UL not determined. High doses are believed harmless, but may turn urine orange or yellow.
Too little: Absorption is decreased in people with hyperthyroidism. Symptoms can include dry, cracked skin and sensitivity to light.
Foods: Organ meats, eggs, milk; fortified cereals and grains. Riboflavin is easily destroyed by light.
Supplements: Generally contained in B-complex or multivitamins, which provide 100% or more of the DV for riboflavin.
Interactions: None known.
Research note: A diet rich in vitamin B-2 may help ward off or slow the progression of cataracts and may help prevent migraine headaches.

Vitamin B-3
Other names: Niacin, nicotinic acid and nicotinamide.
Why: Helps with producing energy from food (sugars and fats); keeps skin, nerves and digestive system healthy.
How much: RDA = 16 mg for men; 14 mg for women.
Too much: UL = 35 mg, though some doctors prescribe higher doses as a treatment to reduce cholesterol and triglyceride levels. Flushing of the face, neck and ears; itching, nausea and headache; can aggravate gout. More serious effects include insomnia, palpitations and liver damage.
Too little: Rare; symptoms include dermatitis, diarrhea and dementia.
Foods: Chicken, tuna, turkey, fish, beef, beans, yeast, peanut butter and salmon.
Supplements: Typically in B-complex and multivitamins, which generally provide 100% or more of the DV.
Interactions: Taking niacin and diabetes medications may interfere with blood glucose control. Some cholesterol medications can reduce niacin absorption. Pregnant women should avoid taking more than the RDA. Take with food.
Research note: Studies link diets rich in vitamin B-3 with a decreased risk of Alzheimer's disease.

Vitamin B-6
Other names: Pyridoxine, pyridoxal, pyridoxamine and pyridoxine hydrochloride.
Why: Needed in more than 100 chemical reactions in the body and for forming amino acids, red blood cells and antibodies; important for nerve and brain function and energy production.
How much: RDA = 1.3 mg for all adults up to age 50; over age 50, 1.7 mg for men, 1.5 mg for women.
Too much: UL = 100 mg. Long-term high doses of B-6 can lead to nerve damage, resulting in pain and numbness of the extremities.
Too little: Rare; symptoms include skin inflammation, sore tongue, depression, confusion and convulsions. Sub-optimal levels are linked to high levels of homocysteine, which can increase the risk of stroke and heart disease.
Foods: Beans, meat, poultry and fish.
Supplements: Found in multivitamins, B-complex and vitamin B-6 supplements; do not exceed a total intake higher than 100% of the DV.
Interactions: Too much vitamin B-6 can decrease the effects of drugs for epilepsy and Parkison's disease. Vitamin B-6 should be taken along with drugs for tuberculosis.
Research note: An Arthritis Foundation-funded study showed that low blood levels of vitamin B-6 decreased as the activity, severity and pain of RA increased. Researchers suggest that inflammation may decrease the level of vitamin B-6.

Vitamin B-12
Other names: Cobalamin, cyanocobalamin and methylcobalamin.
Why: Helps make red blood cells, nerve cells and genetic material; converts folate to its active form.
How much: RDA = 2.4 mcg.
Too much: UL not determined; negative side-effects may include rash.
Too little: Because vitamin B-12 converts folate to its active form, too little B-12 can lead to a folate deficiency, resulting in pernicious anemia -- malformed red blood cells -- causing fatigue, weakness, nausea, loss of appetite and weight loss.
Foods: Found only in foods of animal origin: organ meats; egg yolks, clams and salmon. Fortified foods such as cereal, pasta and bread may contain synthetic versions.
Supplements: Recommended for strict vegetarians, those who've had gastric surgery or those who have a malabsorption disease. Because vitamin B-12 absorption declines with age, it is recommend that people older than 50 get most of their B-12 from fortified foods and supplements. Most multivitamins and B-complex supplements contain 100% or more of the DV.
Interactions: Antacids, drugs for indigestion and reflux disease, cholesterol-lowering medication and the diabetes medication metformin can decrease the absorption levels or production of B-12.
Research note: Maintaining a healthy level of vitamins B-12, B-6 and folic acid may protect bones by keeping blood levels of the amino acid homocysteine from elevating. High homocysteine levels affect the heart and the skeleton. Experts think the substance may wreak havoc with the chemical bonds in bones.

Vitamin C
Other names: Ascorbic acid, L-ascorbic acid and calcium ascorbate.
Why: Builds and maintains collagen and connective tissue; enhances iron and folic acid absorption; acts as an antioxidant; aids wound healing.
How much: RDA = 90 mg daily for men; 75 mg for women; smokers and Vitamin C
Other names: Ascorbic acid, L-ascorbic acid and calcium ascorbate.
Why: Builds and maintains collagen and connective tissue; enhances iron and folic acid absorption; acts as an antioxidant; aids wound healing.
How much: RDA = 90 mg daily for men; 75 mg for women; smokers and people with arthritis should aim for an additional 35 mg daily.
Too much: UL of vitamin C is 2,000 mg daily. Can lead to diarrhea, nausea and risk of kidney stones.
Too little: Weight loss; fatigue; inflamed or bleeding gums; slower healing times; repeated infections and colds.
Foods: Peppers, orange juice, pineapple and other citrus fruits, strawberries, papaya, broccoli, Brussels sprouts, cabbage, cauliflower, kale and kiwi. Cooking destroys vitamin C activity.
Supplements: Daily intake of 200 to 500 mg is frequently recommended for all adults, because many experts think the RDA for vitamin C is too low. Some studies suggest nearly 1,000 mg are needed to maintain plasma levels at high concentrations. Natural and synthetic vitamin C react the same in the body. Additional ingredients, such as rose hips or bioflavonoids, have not been shown to improve benefit.
Interactions: Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin, antibiotics, nicotine, oral contraceptives or corticosteroids increases the need for vitamin C.
Research note: In a recent study of vitamin C consumption and arthritis, people whose diets contained the least amount of the vitamin were three times more likely to be diagnosed with arthritis than those who ate the most fruits and vegetables rich in vitamin C.

Folate
Other names: Folic acid and folacin.
Why: Promotes healthy cell growth and reproduction, formation of DNA; regulates homocysteine levels.
How much: RDA = 400 mcg for adults; 600 mcg for pregnant women. At least half of this intake (200 mcg) should come from the folic acid found in fortified foods and supplements.
Too much: UL = 1,000 mcg daily, or 1 mg. Doses higher than 1,500 mcg (1.5 mg) may cause minor discomfort such as nausea, appetite loss and gas; and can mask a vitamin B-12 deficiency, resulting in nerve and brain damage. Folic acid may be prescribed at levels higher than the UL for people taking methotrexate.
Too little: Increases the toxic effects of methotrexate can increase homocysteine level. Low levels in pregnant women increase the risk of neural tube defects in their babies. Increased risk for certain cancers, depression, heart disease and Alzheimer's disease.
Foods: Spinach, kale, collards, turnip greens, broccoli, garbanzo beans, lentils, peas, pinto beans, oranges, liver and fortified breads, cereals and juices.
Supplements: Multivitamins and B-complex vitamin supplements generally provide 100% of the DV.
Interactions: Antacids, alcohol, antibiotics, aspirin, carbamazepine (Tegretol), some cholesterol-lowering drugs, indomethacin (Indocin), oral contraceptives, methotrexate and sulfasalazine (Azulfidine) can decrease absorption levels or production of folic acid.
Research note: Methotrexate hinders absorption of folate. However, if you take methotrexate for RA, you can safely use folate supplements. In a double-blind, placebo-controlled trial of more than 400 people with RA, folate supplements helped curb the side effects of methotrexate, including liver inflammation. A double-blind study published in the Journal of the American Medical Association report stroke patients who took folate and vitamin B-12 had lower risk of hip fracture compared to those taking placebo.