“There are numerous nutrients—including vitamins—for which low dietary intake may be a cause of concern. These nutrients are:
- calcium, potassium, fiber, magnesium, and vitamins A (as carotenoids), C, and E (for adults)
- calcium, potassium, fiber, magnesium, and vitamin E (for children and adolescents)
- vitamin B-12, iron, folic acid, and vitamins E and D (for specific population groups).
Regarding the use of vitamin supplements, the Dietary guidelines include the following:
- Consume a variety of nutrient-dense foods and beverages within and among the basic food groups. At the same time, choose foods that limit the intake of saturated and trans fats, cholesterol, added sugars, salt, and alcohol.
- Meet recommended nutrient intakes within energy needs by adopting a balanced eating pattern, such as one of those recommended in the USDA Food Guide or the National Institute of Health’s Dietary Approaches to Stop Hypertension (DASH) eating plan.
- If you’re over age 50, consume vitamin B-12 in its crystalline form, which is found in fortified foods or supplements.
- If you’re a woman of childbearing age who may become pregnant, eat foods high in heme-iron and/or consume iron-rich plant foods or iron-fortified foods with an iron-absorption enhancer, such as foods high in vitamin C.
- If you’re a woman of childbearing age who may become pregnant or is in the first trimester of pregnancy, consume adequate synthetic folic acid daily (from fortified foods or supplements) in addition to food forms of folate from a varied diet.
- If you are an older adult, have dark skin, or are exposed to insufficient ultraviolet band radiation (such as sunlight), consume extra vitamin D from vitamin D-fortified foods and/or supplements.”
“Vitamins are not dangerous unless you get too much of them,” he says. “More is not necessarily better with supplements, especially if you take fat-soluble vitamins.” For some vitamins and minerals, the National Academy of Sciences has established upper limits of intake (ULs) that it recommends not be exceeded during any given day. (For more information, visit www.nap.edu/catalog.php?record_id=6432#toc5
Also, the AAFP lists the following side effects that are sometimes associated with taking too much of a vitamin.”
- A (retinol, retinal, retinoic acid): Nausea, vomiting, headache, dizziness, blurred vision, clumsiness, birth defects, liver problems, possible risk of osteoporosis. You may be at greater risk of these effects if you drink high amounts of alcohol or you have liver problems, high cholesterol levels or don’t get enough protein.
- D (calciferol): Nausea, vomiting, poor appetite, constipation, weakness, weight loss, confusion, heart rhythm problems, deposits of calcium and phosphate in soft tissues.
If you take blood thinners, talk to your doctor before taking vitamin E or vitamin K pills.”
- B-3 (niacin): flushing, redness of the skin, upset stomach.
- B-6 (pyridoxine, pyridoxal, and pyridoxamine): Nerve damage to the limbs, which may cause numbness, trouble walking, and pain.
- C (ascorbic acid): Upset stomach, kidney stones, increased iron absorption.
- Folic Acid (folate): High levels may, especially in older adults, hide signs of B-12 deficiency, a condition that can cause nerve damage
Taking too much of a vitamin can also cause problems with some medical tests or interfere with how some drugs work.”
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Excerpts taken from: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm118079.htm