What kind and how much should we take?
In general, the type of vitamins and other supplements we might consider taking is different at every age, nutritional status, and needs; folic acid (Vitamin B9) is recommended during pregnancy because it may avoid the occurrence of “spina bifida,” a malformation of the spine that causes neurological problems. Anemia may require vitamin B12, vitamin D is essential for bone metabolism, etc. Also, as we age, multivitamins and other supplements may improve our health; some studies found that this happens when there is evidence of certain deficiencies.
The National Academy of Sciences’ Institute of Medicine offers the Recommended Dietary Allowances (RDA), which are in essence the average amount of vitamins, minerals, and other nutrients we need daily. The amounts of these food supplements vary according to sex, age, physical condition, pregnancy, etc.
The Food and Drug Administration determines the Daily Values that should appear on food and supplement labels. They are recommendations based on different information as the RDAs, particularly on the amount of calories we need to consume daily. The average for the FDA is 2,000wo thousand calories a day; however, as an average, it would not apply to anyone. Young active men and women need more than this amount and older adults would need much less. We should also consider the percentage of recommended daily values, which also should appear on labels.
As a general rule, any vitamins, supplements, minerals, etc. we take should not be above the 100 percent of daily values; we must also keep in mind that the Daily Values listed on supplements’ labels are based on the FDA’s 2,000-calorie recommendations.
Vitamin: 100 Percent Daily Value
Vitamin A: 3,000 International Units for men, 2,330 for women.
Vitamin C: 60 milligrams (mg)
Vitamin D: 400 IU
Vitamin E: 20 IU natural source or 30 IU synthetic sources
Vitamin K: 80 micrograms (mcg)
Thiamin (B1): 1.5 mg
Riboflavin (B2): 1.7 mg
Niacin (B3): 20 mg
Pantothenic acid (B5): 10 mg
Pyridoxine (B6): 2 mg
Folic acid (B9): 0.4 mg or 400 mcg
Cobalamin (B12): 6 mcg
Biotin: 0.3 mg or 300 mcg
Minerals: 100 Percent Daily Value
Calcium: 1,000 mg or 1 gram (g)
Chloride: 3,400 mg
Chromium: 120 mcg
Copper: 2 mg
Iodine: 150 mcg
Iron: 8 to 10 mg or less.
Manganese: 2 mg
Molybdenum: 75 mcg
Phosphorus: 1,000 mg
Potassium: 3,500 mg
Selenium: 70 mcg
Zinc: 15 mg
A good diet …
The best way to get the vitamins, minerals, and other micronutrients we need is through a nutritionally balanced diet. Sometimes a supplement may be necessary, even when we do not have a vitamin or mineral deficiency; when we reach the age of sixty-five or older, health problems may contribute to an inadequate diet, making it difficult for us to get all the vitamins and minerals we need.
We may lose our appetite as well as some of our ability to taste and smell; depression or problems with dentures can also inhibit eating. If we eat alone, we may not eat enough to get all the vitamins and nutrients we need from food. As we get older, our body may not be able to absorb vitamins of the B and D groups, making supplementation necessary. There is also evidence that a multivitamin may improve our immune function and decrease our risk for certain infections.
For some postmenopausal women, it can be difficult to obtain the recommended amounts of calcium and vitamin D without supplements. Calcium and vitamin D supplements have been shown to protect against osteoporosis. In order to avoid bone fragility in later years, some scientists recommend increasing low-fat dairy products on our diets (the best source of calcium) or taking calcium supplements as early as thirty-five years of age, for women as well as men.
If we do not eat properly, for instance, the recommended five servings a day of fruits and vegetables, then taking a multivitamin supplement may be reasonable. Of course, the best course of action would be to adopt better eating habits. If we eat fewer than one thousand calories a day, we may benefit from a vitamin-mineral supplement. A very low calorie diet limits the types and amounts of foods we eat and in turn, the types and amounts of nutrients we receive. Low calorie diets should only be undertaken with guidance from a physician.
Tobacco use decreases the absorption of many vitamins and minerals, including vitamin B6, vitamin C, folic acid, and niacin. However, vitamin and mineral supplements will not make up for the major health risks caused by smoking. Excessive, long term alcohol use impairs the digestion and absorption of vitamins B1 and B6 and also vitamins A, D, and B12.
Metabolism disturbances also affect the absorption of minerals such as zinc, selenium, magnesium, and phosphorus. If we drink excessively we may substitute alcohol for food, resulting in a diet lacking in essential nutrients. Alcohol use may cause many birth defects, the most serious being fetal alcohol syndrome. At this point we do not know exactly how much alcohol it takes to cause alcohol-related birth defects. It is best not to drink any alcohol during pregnancy.
More than one drink on a daily basis—for women or anyone age sixty-five or older, and more than two drinks a day for men is considered excessive.
For women who become pregnant, there is a need for more calcium, folic acid, and iron. Folic acid helps prevent neural tube defects, such as spina bifida in the baby. Iron prevents fatigue by helping the formation of new red blood cells, which also increases the oxygen delivery to the baby through the placenta.
If during pregnancy the diet has limited variety because of food allergies or intolerance to certain foods, a vitamin-mineral supplement is indicated. Vegetarians who eliminate all animal products from their diet may need additional group B vitamins, particularly B6, B12, and Folic Acid. If the diet does not include dairy products and there is little or no sun exposure, supplements with calcium and vitamin D are a must.
Vitamins and minerals supplements are also indicated after surgery of the digestive tract and when treating diseases of the liver, gallbladder, intestine, or pancreas. The use of antacids, certain antibiotics, laxatives, diuretics, and other medications also interfere with the absorption of many nutrients.
By Annie M. Williams, MD
Part 1 | Part 2