Pregnant or nursing women may be able to reduce their chances of developing postpartum depression and improve the neurological development of their babies by increasing their consumption of the essential fatty acid DHA, according to David Kyle, PhD, the US director of the Mother and Child Foundation. DHA (docosahexaenoic acid) is an omega-3 fatty acid mostly found in fish like tuna and salmon and in algae.
Approximately 15-20 percent of women who give birth in the United States develop postpartum depression, according to Kyle, who spoke today at the 223rd national meeting of the American Chemical Society, the world's largest scientific society. "We believe that the high incidence of postpartum depression in the United States may be triggered by a low dietary intake of DHA," he said.
Kyle's organization studies nutrition for mothers and its effect on their babies. While DHA has been recognized as beneficial to infants, there has been less public awareness of the apparent link between DHA and postpartum depression, according to Kyle. He described a number of independent studies that appear to verify this connection, and urged that more attention be given to the role of DHA in nursing and pregnant women.
Kyle noted a study by Dr. Joseph Hibbeln of the National Institutes of Health that found a "highly statistically significant inverse correlation" between the intake levels of DHA and incidents of clinical depression. "The higher the intake of DHA, the lower the incidence of depression," Kyle emphasized. That study was published in the journal Lancet in 1998.
Kyle also pointed out that a more recent study by Hibbeln has "found exactly the same correlation" between the incidence of postpartum depression and levels of DHA in breast milk. This study specifically looked at DHA in breast milk, as opposed to DHA intake, and postpartum depression rather than overall clinical depression, Kyle added. The study was first presented last year at a meeting of the American Psychological Association.
A Dutch study, which Kyle also cited, found that during pregnancy the placenta pumps DHA from the expectant mother to the fetus, thus depleting the woman's DHA levels and making her more susceptible to depression. That 1997 study was done by Gerrard Hornstra, Ph.D., of Maastricht University in the Netherlands.
Clinical studies show that the level of DHA in mother's milk is dependent upon a woman's diet, according to Kyle. U.S. women typically consume about 40-50 milligrams of DHA in their daily diet compared to about 200 milligrams for Europeans and about 600 milligrams for Japanese women, he noted. "The DHA content of mother's milk in the United States is among the lowest in the world," Kyle added. Babies who receive sufficient levels of DHA either in mother's milk or from DHA-supplemented infant formulas also benefit, Kyle emphasized. He noted a study by Dr. Craig Jensen at the Baylor College of Medicine in Houston, Texas, with nursing mothers -- half given 200-milligram DHA supplements and the other half given placebos -- that showed the DHA content in the milk of the women in the supplemented group was double that of the control group.
"The toddlers, who were nursed from the mums getting the extra DHA, performed significantly better [on standard neurological motor function tests] than those toddlers nursed from mums who were getting the placebo," Kyle said. The Baylor study tracked the children's neurological development during their first two and a half years.
Last year, the U.S. Food and Drug Administration approved the addition of DHA in infant formulas sold in this country. DHA-supplemented formula is already available in about 60 countries around the world, Kyle said. Earlier this year, the two major manufacturers of infant formulas sold in the United States announced plans to introduce DHA-supplemented formulas for the U.S. market.
The only type of DHA supplementation so far approved by the FDA for infant formulas sold in the United States is an oil derived from micro algae. Kyle's former company, Martek Biosciences Corporation, which he co-founded in 1985, is the only manufacturer of the oil.
Kyle recommends that women who want to increase their own levels of DHA can either take dietary supplements, which are available in grocery stores and pharmacies, or eat grilled, broiled or baked fish.