Overloading on vitamins can pose health risks

We live in the land of excess. We eat too much and in too-large portions. We drive supersized vehicles that burn too much gas. And we spend way too much time in front of the computer or TV. So, it should be no surprise that when it comes to vitamin and mineral supplements, we often take the attitude that if one is good, three or four are better.

"If you assume that because vitamins are natural, more is better, you'd be mistaken," says Cheryl Rock, researcher and professor of nutrition at the University of California San Diego's School of Medicine. "You'd also be mistaken if you think that the government wouldn't let something be on store shelves if it could harm you. There is no (government regulation) of vitamin and nutritional supplements."
According to the Office of Dietary Supplements at the National Institutes of Health, more than 50 percent of American households buy vitamins to help protect them from everything from cancer and heart disease to aching joints and the sniffles.

The problem is we also get vitamins and nutrients from the foods we eat, including an increasing number of vitamin-enriched and fortified foods. When megadoses of supplements are added to the mix, this can result in some vitamin and mineral overloads. So, although we're trying to improve our health, we may actually be damaging it.

While some dietary supplement regimens "can make sense as a focused individualized approach (monitored) by your health-care provider," an excess may cause more harm than good, says Dr. Robert Bonakdar, director of pain management at the Scripps Center for Integrative Medicine in San Diego.

TOO MUCH OF A GOOD THING

- Vitamin B-6 (also called pyridoxine)

RDA: (recommended daily allowance) 1.3 milligrams per day for men and women under 51; after age 51, 1.5 milligrams for women and 1.7 milligrams for men

UL: (tolerable upper intake level) 100 milligrams for men and women

Why we need it: Aids in protein metabolism; helps make red blood cells

Risks of excessive dosage: Can cause temporary nerve damage with loss of feeling in hands and feet; muscle weakness

Vitamin B-6-rich foods: Meat, fish, poultry, beans, whole grains, green leafy vegetables.

- Vitamin C

RDA: 75 milligrams per day for women; 90 milligrams per day for men

UL: 2,000 milligrams per day (men and women)

Why we need it: A potent anti-oxidant; promotes wound healing and iron absorption; improves the immune system

Risks of excessive dosage: May cause kidney stones; diarrhea

Vitamin C-rich foods: Citrus fruit, cantaloupe, strawberries, tomatoes.

- Vitamin D

RDA: 5 micrograms or 200 IU (international units) per day for men and women, age 19-50; 10 micrograms or 400 IU for ages 51-70; 15 micrograms or 600 IU for age 71-plus

UL: 50 micrograms or 2,000 IU for men and women

Why we need it: Helps with calcium and phosphorous absorption; regulates cell growth

Risks of excessive dosage: Absorption of too much calcium, which can result in the hardening of tissues and kidney stones; nausea, constipation

Vitamin D-rich foods: Fish, liver, eggs, calcium-fortified foods and sunlight.

- Vitamin E

RDA: 15 milligrams or 22.5 IU (international units) per day for men and women

UL: 1,000 milligrams or 1,500 IU per day (men and women)

Why we need it: A potent anti-oxidant, it protects cells against free radicals; promotes proper immune function and DNA repair

Risks of excessive dosage: May act as an anti-coagulant and increase the risk of bleeding problems; may increase the risk of heart failure

Vitamin E-rich foods: Peanut butter, wheat germ oil, nuts, leafy green vegetables.

- Calcium

RDA: 1,000 milligrams per day for men and women; after age 50, 1,200 milligrams per day

UL: 2,500 milligrams (men and women)

Why we need it: Builds strong bones and teeth; promotes proper functioning of muscles and nerves; helps blood clot

Risks of excessive dosage: Kidney stones; constipation; gastrointestinal distress

Calcium-rich foods: Yogurt, sardines, dairy products, tofu.

- Iron

RDA: 18 milligrams per day for women age 19-50; 8 milligrams for women 51 and older; 8 milligrams per day for men any age

UL: 45 milligrams per day (men and women all ages)

Why we need it: Helps transport oxygen in the blood; essential for the regulation of cell growth

Risks of excessive dosage: Gastrointestinal distress; constipation; a higher risk of heart disease; can be fatal to children

Iron-rich foods: Oysters, beef, liver, chicken liver, enriched breakfast cereals, blackstrap molasses.

- Zinc

RDA: 8 milligrams per day for women; 11 milligrams per day for men

UL: 40 milligrams (men and women)

Why we need it: Helps tissue healing and skin condition; promotes cell reproduction

Risks of excessive dosage: Impairs the immune system; interferes with copper absorption

Zinc-rich foods: Oysters, beef, seafood, liver.

- Vitamin A

RDA: 700 micrograms per day for women; 900 micrograms per day for men

UL: 3,000 micrograms per day (men and women)

Why we need it: Promotes normal vision; needed for cell growth; protects against infection.

Risks of excessive dosage: May cause liver damage; birth defects if taken in excess while pregnant; and increased risk of hip fractures in women

Vitamin A-rich foods: Dairy products, green leafy vegetables, carrots and cantaloupe.

- Beta Carotene

RDA: Not established

UL: Not established

Why we need it: Promotes normal vision and regeneration of vital tissue

Risks of excessive dosage: Increased risk of lung cancer in smokers, former smokers or anyone with lung problems; can turn skin orange temporarily

Beta carotene-rich foods: Carrots, dark green leafy vegetables, red and yellow vegetables and fruit.

- Niacin (vitamin B-3)

RDA: 14 milligrams per day for women; 16 milligrams per day for men

UL: 35 milligrams (men and women)

Why we need it: Helps metabolize food for energy; promotes healthy skin and nervous system

Risks of excessive dosage: May cause peptic ulcers; liver damage; gastrointestinal upsets; skin rashes.

Niacin-rich foods: Chicken, tuna, salmon, whole grains.