Pregnancy and the Use of Nutritional Supplements - Women's Health Update

Townsend Letter for Doctors and Patients,  Jan, 2002  by Tori Hudson

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Vitamin B-6 (pyridoxine): 2.2 mg per day, RDA

Nursing: 2.1 mg per day

Food sources: whole grains, wheat germ, egg yolks, peas, carrots

Vitamin B12

The coenzyme form of vitamin B12 is a very complex molecule containing cobalt, designated in humans as cobalamin, which is required for proper homocysteine metabolism. At least 12 different inherited inborn errors of metabolism related to cobalamin are known; low plasma vitamin B12 levels have been shown to be an independent risk factor for neural tube defect in one study. (40) Supplementation is recommended and may also help in prevention of anemia. Food sources are cauliflower and broccoli. Herbal sources are alfalfa, comfrey, miso, seaweeds, and catnip.

Vitamin B-12 (cobalamin): 2.2 mcg per day, RDA

Nursing: 2.6 mcg per day

Food sources: cauliflower, broccoli

Herbal sources: alfalfa, catnip, comfrey, miso, seaweed

Vitamin A

Daily doses of 40,000 units or more of vitamin A during pregnancy may be toxic, (41) while doses lower than 10,000 units appear to be safe. (42) A study of 22,000 pregnant women, those who consumed more than 15,000 units of vitamin A per day from food and supplements, or 10,000 units as a supplement, showed a significant increase in birth defects associated with cranialneural-crest tissue (several-fold higher incidents of birth defects). (43) Most of these women consumed the vitamin A before the seventh week of pregnancy. Rat studies show a possible link to folic acid metabolism. (44) Elevated levels of vitamin A in the blood have also been correlated with low birth weights. (45)

Preterm infants have been shown to be deficient in vitamin A, which may predispose them to development of chronic lung disease. (46) Healthy pregnant women who developed pre-eclampsia were shown to be deficient in vitamin A (but not beta-carotene). (47) Pre-eclampsia is a potentially dangerous condition characterized by high blood pressure, swelling, and /or protein spilling into the urine. Supplementation with no more than 6,000 units of vitamin A is recommended. (48) Beta-carotene, which has the same positive effects as vitamin A, has not been associated with toxicity or teratogenicity in humans or animals. (49)

Plant sources of the nontoxic "provitamin A" beta carotene are organic fruits and vegetables, especially yellow and orange ones; for example, one sweet potato or one cup of carrot juice contains 25,000 IU of beta carotene. (50)

Vitamin A: more than 6,000 IU daily is NOT OR RECOMMENDED

Beta carotene: 10.000 i.u.

Food sources: yellow and orange fruits and vegetables

Herbal sources: alfalfa, cayenne, comfrey, dandelion, elderberries, lamb's quarters, seaweed

Vitamin C

Vitamin C plays a vital role in the formation of collagen -- a major protein found in connective tissue, cartilage, and bone, and is "chronically underdosed." It is essential to the nerves, healthy gums and teeth, and prevents infection. Although one study showed that women who took 5000 mg. of vitamin C daily during pregnancy delivered healthy infants who developed scurvy (preg-rel. 528), (51) this "rebound scurvy" is very rare, and the infant recovers quickly without treatment. Supplementation with vitamin C may be as effective as calcium for leg cramps during pregnancy. (52)