The need for several essential nutrients increases with age and sickness. This applies, for example, to vitamin C, vitamin D, magnesium, and iron. In 2017 the Norwegian Food Safety Authority proposed to revise the official maximum levels for vitamins and minerals in dietary supplements.  Their proposal introduced four different age categories with separate maximum intakes. Initially, the agencies proposed to revise the daily doses allowed in dietary supplements for folic acid, magnesium, calcium, vitamin C and D. At the same time, maximum rates were temporarily suspended for vitamins A, E, K, thiamine (B1), riboflavin (B2), niacin (B3), pantothenate (B5), pyridoxine (B6), cobalamine (B12), biotin, and for phosphorus, iron, copper, iodine, zinc, manganese, selenium, chromium, molybdenum, sodium, potassium, fluoride, chloride, boron and silicon. The upper limits for some nutrients may be changed in the future. Unfortunately, Norwegian nutrition "experts" will likely continue to limit allowable doses below those freely available in the US and even Sweden.
SOURCES: Elaine Turner, PhD, RD, associate professor, department of Food Science and Human Nutrition, University of Florida, Gainesville. Sharon B. Spalding, MEd, CSCS, professor, physical education and health; and associate director, Virginia Women's Institute for Leadership, Mary Baldwin College Staunton, Va. American Dietetic Association web site. Institute of Medicine at the National Academies web site.
Supplements are most likely to cause side effects or harm when people take them instead of prescribed medicines or when people take many supplements in combination. Some supplements can increase the risk of bleeding or, if a person takes them before or after surgery, they can affect the person's response to anesthesia. Dietary supplements can also interact with certain prescription drugs in ways that might cause problems. Here are just a few examples:
Protein gives you the energy to get up and go—and keep going—while also supporting mood and cognitive function. Too much protein can be harmful to people with kidney disease, but the latest research suggests that many of us need more high-quality protein, especially as we age. That doesn’t mean you have to eat more animal products—a variety of plant-based sources of protein each day can ensure your body gets all the essential protein it needs. Learn more »
Eat a balance of carbohydrates, proteins and fats at each meal and choose foods rich in fiber, vitamins and minerals. A good way to do this is to fill your plate with 3–4 food groups at each meal. Eat a combination of protein-rich foods, whole grains, dairy, fruits and vegetables, and incorporate the groups you miss into other meals and snacks throughout the day. Stick to healthy portions — see our Essential Guide to Portion Sizes for tips.
Considering average dietary needs and the prevalence of certain health conditions, some basic guidelines may provide the foundation for the effective use of nutritional supplements. First, a high quality, broad-spectrum multivitamin and mineral supplement, taken once per day, is recommended to provide a range of nutrients. This should contain the B-complex vitamins B6, B12, and folic acid, which may help prevent heart disease, and the minerals zinc and copper, which aid immunity. In addition to a multivitamin, antioxidants can be added to a supplementation routine. These include vitamin A (or beta-carotene), vitamin C, and vitamin E, and the mineral selenium. Antioxidants may have several positive effects on the body, such as slowing the aging process, reducing the risks of cancer and heart disease, and reducing the risks of illness and infection by supporting the immune system. Coenzyme Q10 is another antioxidant in wide usage, as studies have shown it may improve the health of the heart and reduce the effects of heart disease. Essential fatty acids, particularly omega-3, are also recommended as they are involved in many important processes in the body, including brain function. Calcium supplementation is recommended for the elderly and for women, to strengthen bones and prevent bone loss. Calcium supplements that are balanced with magnesium have a less constipating effect and are better absorbed.
Dietary supplements are complex products. The FDA has established good manufacturing practices (GMPs) for dietary supplements to help ensure their identity, purity, strength, and composition. These GMPs are designed to prevent the inclusion of the wrong ingredient, the addition of too much or too little of an ingredient, the possibility of contamination, and the improper packaging and labeling of a product. The FDA periodically inspects facilities that manufacture dietary supplements.