Women who take fish oil during their third trimester of pregnancy might cut their children’s risk of developing asthma by as much as one-third, a new clinical trial suggests.
The fish oil dose was high – with fatty acid levels that were 15 to 20 times more than the average American gets from food. But there were no significant side effects, according to lead researcher Dr. Hans Bisgaard. He’s a professor of pediatrics at the University of Copenhagen, in Denmark.
The study, published Dec. 29 in the New England Journal of Medicine, adds to evidence that fish oil may help ward of asthma.
In an editorial published with the study, Dr. Christopher Ramsden, a researcher with the U.S. National Institutes of Health, called the results “highly promising.” Still, he writes, “a note of caution is warranted.” Because the fil oil doses were high – 2.4 grams per day – research should look at whether the treatment has any negative longer-term effects, Ramsden said.
For the study, Bisgaard’s team randomly assigned 736 pregnant women to take either fish oil capsules or a placebo every day during the third trimester. The placebo capsules contained olive oil.
In the end, children in the fish-oil group were about one-third less likely to develop asthma or persistent wheezing – a sign of asthma in very young children. By the age of 5, nearly 17% were diagnosed with either condition, versus almost one-quarter of the children in the placebo group.
Dr. Jefry Biehler, chairman of pediatrics at Nicklaus Children’s Hospital in Miami stated that studies of other populations are needed as the study was done in Denmark, where fish intake is relatively high. “Women in the lower third of intake in Denmark are well above the average intake in the U.S.” Bisgaard said. “I expect a stronger effect in the populations that are inland, where fish is more unusual in the diet.”
Biehler recommended that pregnant women talk with their doctors before using fish oil – and make sure that any product they use is “high-quality.”
I use 2 grams of fish oil as my maintenance dose for patients. To reduce inflammation, I routinely recommend 4 grams per day. The dosage in this study wasn’t high by Denmark standards, it’s just that the intake of fish oil in the U.S. is woefully low.
I also question the placebo used in this study. Olive oil is an omega-6 fatty acid and is converted by the body to PG-1 (prostaglandin 1). EPA and DHA are omega-3 fatty acids and are converted to PG-3. Both have anti-inflammatory effects.
Finally, the comment about “high quality” by Dr. Biehler. Mercury contamination of fish oil is a serious issue. Reputable supplement companies pay to have the mercury removed by the processing plants. However, few companies have the laboratory resources to test fish oil for mercury contamination. Standard Process and Biotics have such labs.
The Bottom Line:
Fish oil must be supplemented in the diet of all Americans and is especially important during pregnancy. I recommend 2 grams per day as a minimum. Make sure the product you take says “mercury free” or processed through “high density molecular extraction”.
Source: December 29, 2016 National Institutes of Health