The study, published in American Journal of Clinical Nutrition, examined the relationship between the type of fat a mother consumed at mid-pregnancy and whether her child was obese at age 3 – determined by body mass index (BMI) and skinfold measurements
The researchers, led by Dr. Emily Oken, associate professor in the department of population medicine, reported that enhanced maternal-fetal omega-3 status was associated with lower childhood obesity.
“We examined the extent to which prenatal omega-3 and omega-6 PUFA concentrations were associated with childhood adiposity,” wrote Onken and her colleagues.
“A higher ratio of cord plasma omega-6 to omega-3 polyunsaturated fatty acids (PUFAs) was associated with higher subscapular and triceps [skinfold thicknesses] and odds of obesity,” they said.
Omega-3 and obesity
The consumption of omega-3 fatty acids, most notably EPA and DHA, is associated with several health benefits, including improving of lipid metabolism, preventing coronary heart diseases, and reducing inflammatory responses. In addition, omega-3s have been suggested to reduce fat levels in animals fed a high-fat diet.
Onken and her colleagues explained that a low intake of omega-3 fatty acids, found mainly in fish and seafood, in addition to a presence of large amounts of omega-6s has been suggested to be a risk factor in the development of obesity.
Previous research in animals found that such imbalances in the types of fatty acids in the diet, promotes the development of fat tissue. However, the authors noted that very few studies have investigated these effects in human populations.
Onken and her colleagues reported that around one fifth expectant mothers ate more than 2 fish meals per week at mid-pregnancy, however only about half of these women achieved the recommend intake of DHA of 200 mg per day.
The authors said that such an observation suggests although pregnant women ate fish, they did not consume enough of the species known to contain high amounts of DHA, such as salmon, tuna, and mackerel.
Only three per cent of pregnant women in the study were found to consume the recommended intake of 200 mg/day of DHA in the last month of pregnancy. Onken and her team noted that this is the time when large amounts of DHA are transferred from the mother to the infant to support brain development.
The research team then calculated the odds for obesity in the offspring at age 3 according to the mother’s omega-3 fatty acid intake and the level of omega-6s and omega-3s in cord blood at delivery.
Onken and her co-workers reported the odds of obesity in 3-year-olds were between two and four times higher when cord blood had a high ratio of omega-6 to omega-3 fatty acids.
In contrast, the odds of obesity were 32 per cent lower when maternal consumption of omega-3s was high or if the ratio of omega-3 to omega-6 was at close to recommended levels.
The Harvard research team noted that the study is the first indications from human data that low intakes of omega-3s in the presence of large amounts of omega-6s during pregnancy might affect the chance of obesity in the offspring.
“These findings need to be confirmed by others. It will also be important to demonstrate that making deliberate changes to a woman’s fat intake during pregnancy has desirable effects on weight and fatness in children,” they added.
Source: American Journal of Clinical Nutrition
Volume 93, Issue 4, Pages 780-788, doi: 10.3945/ajcn.110.005801
“Prenatal fatty acid status and child adiposity at age 3 y: results from a US pregnancy cohort”
Authors: S. M Donahue, S.L Rifas-Shiman, D.R. Gold, Z.E Jouni, M.W Gillman, E. Oken.