Mothers’ Nutrition Linked to Down Syndrome
Maternal intake of iron and folic acid during the first month of pregnancy may be protective against Down syndrome (DS), reports a study in Nutrition (2005;21:698–704).
DS is a developmental disorder that results from a chromosomal abnormality. Most of the cells in the human body contain 23 pairs of chromosomes. In the case of DS, there are three versions of chromosome number 21, instead of the usual two. Children with DS have characteristic facial features including a small nose with a flattened bridge, small mouth, eyes that slant slightly upward, and small ears. The syndrome is accompanied by mental retardation that is usually mild to moderate in severity. About one-half of children with DS are born with heart defects that often require surgical repair. People with DS are more likely to have vision and hearing problems, hypothyroidism (an underactive thyroid gland), and frequent infections. Children with DS are also about 20 times more likely to develop leukemia than are other children.
The risk of having a baby with DS increases with advancing maternal age. While a 25-year-old woman has less than a 1 in 1,000 chance of having a baby with DS, a 35-year-old has a 1 in 400 chance. Prenatal screening and diagnostic tests may be useful for identifying the condition before birth.
While the exact mechanism leading to the chromosomal abnormality in DS is not fully understood, some research suggests that errors in folic acid metabolism may play a role. The new study evaluated the effect of a mother’s intake of certain vitamins and minerals on the incidence of DS. The study compared nutrient intakes during pregnancy of mothers of babies with DS with nutrient intakes in the following groups: 781 mothers whose babies did not have DS, but who otherwise shared similar characteristics with mothers of DS babies (matched controls); 22,843 mothers of babies with birth defects other than DS; and 38,151 mothers of healthy babies. Data regarding the use of vitamins, minerals, and medications during pregnancy was ascertained by mailed questionnaires, medical records, and home nurse visits.
Women who took folic acid and iron during the first month of pregnancy had a significantly lower chance of having a baby with DS than did women who hadn’t taken these nutrients. These nutrients were not protective, however, if supplementation was started after the first month. That finding suggests that the chromosomal changes that lead to Down syndrome occur early in the course of pregnancy, and that the protective nutrients must be taken at that time in order to be beneficial. Among women supplementing with folic acid, nearly 70% took 6 mg per day; this is substantially more than the current recommendation by the March of Dimes of 0.4 mg to prevent neural tube defects (a kind of birth defect). Importantly, small doses of folic acid (less than 1 mg per day) did not appear to protect against DS. Women who supplemented with iron took an average of 30 to 60 mg per day; this amount is comparable to that found in most prenatal vitamins. The effects of the individual nutrients were difficult to establish because iron and folic acid were usually taken simultaneously; however, iron did appear to exert a protective effect when taken alone.
The results of other studies suggest that high doses of folic acid (6 to 10 mg per day) also protect against cleft lip and cleft palate. Taking high doses of folic acid may promote the development of zinc deficiency and may also interfere with the laboratory diagnosis of vitamin B12 deficiency. Therefore, taking folic acid in amounts greater than about 1 mg per day should only be done under the supervision of a qualified healthcare professional.
Kimberly Beauchamp, ND, received her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She is a co-founder and practicing physician at South County Naturopaths, Inc., in Wakefield, RI. Dr. Beauchamp teaches holistic medicine classes and provides consultations focusing on detoxification and whole-foods nutrition.
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