What Are the Benefits of Multivitamins?
Vitamins and minerals are substances your body needs to survive, grow, and work the way it should. Different vitamins and minerals have different jobs, affecting everything from your nerves and bones to how well your blood clots.
Eating a balanced diet with plenty of vegetables, fruits, and whole grains should provide the vitamins and minerals you need. But if you can't always eat healthy meals, taking supplements might help.
About one-third of American adults take daily supplements containing multiple vitamins and minerals. These are commonly known as multivitamins.
Benefits of Multivitamins
Multivitamins are designed to fill gaps in your diet. There are different brands containing different combinations of vitamins and minerals. The label on each product should list the percent daily value (DV) or recommended dietary allowance (RDA) of the nutrients in one serving.
A label that lists 100% DV of vitamin D means the formula provides 100% of the vitamin D you need each day. This is based on a 2,000-calorie diet, so if you eat more or less, you'll need to make some adjustments.
Some people are more likely than others to benefit from the nutritional boost of a multivitamin. Talk to your doctor if you are:
Pregnant or could become pregnant
Obstetricians and gynecologists recommend special prenatal multivitamin formulas designed to support healthy pregnancies.
A postmenopausal woman
You might need extra calcium and vitamin D to strengthen bones and prevent osteoporosis.
Age 50 or over
Older adults have more trouble than younger people absorbing Vitamin B12 from from food. The vitamin helps form red blood cells, supports brain and nerve function, and makes DNA. Supplements and fortified foods can help older adults get enough.
Certain prescription drugs can deplete the body of important minerals like magnesium, calcium, and potassium. Others prevent your body from absorbing some nutrients.
On a limited diet
If you can't eat a wide variety of healthy foods, have a poor appetite, or choose not to eat from some food groups, a multivitamin might fill the gap.
Living with digestive problems
Conditions that interfere with digestion can prevent your body from absorbing enough nutrients. That's called malabsorption. These include:
- Celiac disease
- Ulcerative colitis
- Cystic fibrosis
- Gastric bypass surgery
- Alcoholism or alcohol abuse
- Lactose intolerance
- Chronic pancreatitis
- Whipple disease
- Any illness that causes frequent diarrhea or vomiting
What Happens to Your Body When You Start Taking Vitamins?
Vitamins are necessary for many of your bodily functions. Despite that fact, studies have not found that taking a multivitamin is a reliable way to reduce your risk of heart disease, cancer, or an early death. But if you are short on essential nutrients in your diet, taking a multivitamin might help you:
Maintain organ and vision health
Vitamin A is essential for vision, immune function, and communication between your cells. It also plays an important role in maintaining the health of your heart, lungs, kidneys, and other organs.
Have a healthy baby
Folic acid taken in the first months of pregnancy helps prevent certain birth defects of the brain and spine. It's essential for anyone who is or might become pregnant. The recommended RDA is 400 micrograms or 100% DV. Some cereals, breads, pastas, rice, and other foods have added folic acid.
Maintain strong bones
A multivitamin can help you get enough calcium and vitamin D, which work together to keep bones strong and ward off osteoporosis (bone thinning). Calcium builds bone and vitamin D helps your bones absorb calcium.
Calcium needs are especially high for teens, who need 1,300 milligrams a day, and for women over age 50 and men over age 70, who need 1,200 milligrams daily. One cup of milk or fortified juice contains about 300 milligrams. A typical multivitamin may contain 200 to 300 milligrams along with some vitamin D. Separate calcium supplements might have 500 milligrams or 600 milligrams and might be combined with vitamin D as well.
Groups who might get too little vitamin D include breastfed infants, older adults, people who spend most of their time indoors, people with dark skin, and people with obesity. Many of these people might need fortified foods or supplements, since vitamin D is hard to get through common foods.
Support your immune system
Your immune system won't work as well as it should to fight off infections and other health problems if you don't get enough vitamins and minerals -- including vitamins A, B6, B12, C, D, E, and K; folate; and copper, iodine, iron, magnesium, selenium, and zinc. If you aren't short on these nutrients, though, taking a multivitamin probably does little or nothing to prevent or treat infections, studies show.
Some studies suggest that if you regularly take vitamin C, your colds might be shorter and milder, but that taking the vitamin when you are already sick doesn't help.
Side Effects of Multivitamins
For most people, there isn’t much risk associated with taking multivitamins. Still, you should speak to your doctor before you take one. Combining a multivitamin with other vitamin supplements, vitamin sources, or medication can cause serious health complications. For example, the vitamin K found in many multivitamins could decrease the effectiveness of blood thinning drugs.
The FDA doesn't regulate multivitamins. Look for brands with the United States Pharmacopeia (USP) on the label to ensure you're getting a high-quality formula.
Risks to consider:
Cancer in smokers
Smokers, and possibly former smokers, should avoid any supplements with high levels of beta-carotene or vitamin A. Two studies linked these nutrients with an increased risk of lung cancer in smokers.
Check the iron levels in your multivitamin. In men and postmenopausal women, this mineral can accumulate in the body and cause organ damage. Multivitamins made for men and older women contain little or no iron, so stick to those formulas. You can get plenty of iron from foods like chicken, small amounts of red meat, dark leafy greens, and fortified-grains.
Liver or bone damage
Avoid multivitamins with high levels of retinol, listed as acetate or palmitate on the label. Retinols can be harmful to your bones and liver.
High levels of vitamin D might increase the risk of developing kidney stones. But studies suggest no increased risk for people who take up to 1,000 IU a day.
Until recently, water-soluble vitamins such as B and C were considered nontoxic, even at high doses. But now evidence is emerging that B6 megadoses can cause serious nerve damage.
Multivitamins vary widely by brand or formulation. Each bottle or box will have a detailed label that lists all the vitamins and minerals in each supplement.
Most brands create a multivitamin that is tailored to the DV for men, women, children, and pregnant women. You should find a multivitamin that meets the DV recommended for your group.
One serving size is one or two tablets daily. Read the label carefully to avoid taking too much or too little of the daily recommended amount.
There aren't any hard and fast rules for the best time of day to take a multivitamin. Some people choose to take it in the morning, while others wait until lunch or even dinner. If you have a sensitive stomach, you should consider taking your multivitamins with a meal to avoid nausea or cramping.