Folic acid, a B-vitamin, protects against serious birth defects when women of childbearing age get 400 micrograms daily from dietary supplements and/or fortified foods. And omega-3 fatty acids from fish oils can lower blood triglyceride levels and may help guard against heart disease.
More is not always better, however. Excess vitamin A, for example, can bring on headaches, liver damage and birth defects in pregnant women. And “natural” products are not necessarily more safe. Naturally poisonous mushrooms can kill you.
We seem to have this idea that only prescription medicines have unwanted side effects. Yet anything we put into our bodies will affect us in some way. Dietary supplements have active ingredients, too.
For example, St John’s wort — a plant-based dietary supplement — has shown in a few small studies to ease the effects of depression. It can also increase one’s sensitivity to sunlight and weaken the intended action of several medications including antidepressants, contraceptives and anticoagulants, say researchers. Certain herbs such as comfrey and kava can cause liver damage.
Find more facts about dietary supplements at www.ods.od.nih.gov.
(Barbara Quinn is a registered dietitian and certified diabetes educator affiliated with Community Hospital of the Monterey Peninsula. She is the author of "Quinn-Essential Nutrition" (Westbow Press, 2015). Email her at to firstname.lastname@example.org.)