The combination of supplements does not normally interfere with their functioning and, in some cases, can be beneficial. For example, vitamin C helps the absorption of iron. Just because supplements are safe in moderation doesn't mean that more is better. Combining several supplements or taking doses higher than recommended may increase the risk of them causing harm, according to Kitchin.
Once you know what you need most, the next logical step is to add supplements of those vitamins to your daily routine. Supplements have labels that indicate how much of a dose of the recommended diet needed, so that's where you can fill the gap, Dr. Bailey says, adding that aiming for 100 percent is a good barometer to follow. The problem arises when you don't track the percentage.
So what's the first physical indicator that you're consuming too much of something? Dr. Bailey says that every nutrient has different warning signs, but the Office of Dietary Supplements, which is related to the National Institute of Health, has some pretty surprising fact sheets that describe everything in great detail. Multivitamins appear to be safe for long-term use. However, too much of anything can be harmful, and dietary supplements are no exception.
Taking two multivitamins a day can cause serious toxicity. The USPSTF postponed making recommendations on the use of multivitamins and single or combined nutrient supplements (other than beta-carotene or vitamin E) for the prevention of cardiovascular disease and cancer due to lack of evidence. If people choose to take a multivitamin complex, it's best to look for one that doesn't exceed 100% of the daily value of any nutrient and avoid spending a lot of money, Kitchin said. Some dietary supplements contain too much of certain vitamins and minerals, which can cause side effects.
Kitchin also recommended calcium and vitamin D supplements to some patients at risk of osteoporosis, but he always analyzes their diet first before prescribing them. However, large doses of calcium supplements can cause kidney stones, constipation, and poor absorption of iron and zinc. Taking a vitamin D supplement can help, and the CRN survey shows that this supplement is becoming more popular, but it's important to monitor the dose to make sure you don't consume more than 100 micrograms (mcg) a day. In addition, a previous study found that men who took vitamin C supplements had a higher risk of developing kidney stones.
Energy bars, meal replacement drinks, protein shakes, cereal bars and cereal itself contain lots of vitamins and minerals, up to 100% of the recommended daily allowance (RDA). Even if none of the supplements separately exceeds the maximum limit for a given nutrient, combining several pills, such as a multivitamin and an additional vitamin D capsule, for example, can result in higher doses than recommended. However, most people still don't get the right vitamins despite their best efforts, says Jeffrey Blumberg, PhD, professor of nutrition at Tufts University in Boston. And while most people don't get enough potassium even when diet and supplements are combined, according to the NIH, people with chronic kidney disease may develop abnormally high levels of potassium in their blood.
Conversely, certain nutrients such as vitamin A, vitamin E and beta-carotene may increase the risk of death especially when consumed in large doses. People who eat a lot of nutrient-rich foods live longer healthier lives so enjoy lots of fruits vegetables and whole grains and talk to a healthcare provider if you're not sure if taking supplements would benefit you. However the report clarified that vitamins containing beta-carotene and vitamin E are unlikely to prevent either. In the Dietary Supplement Health and Education Act of 1994 Congress defined supplements as products (other than tobacco) intended to supplement the diet containing one or more dietary ingredients (including vitamins minerals herbs botanicals amino acids or other substances) or their components intended to be taken orally in pill capsule tablet or liquid form and labeled as a dietary supplement.