UNIVERSITY PARK, PENN. — A team of researchers from Penn State University have conducted a study that shows plant-based omega-3 polyunsaturated fatty acids may have a protective effective on bone health. The research study was supported by the California Walnut Commission and by Penn State’s General Clinical Research Center NIH grant.
During the course of the study, researchers carefully controlled participants food intake, a unique feature of the study, said Dr. Rebecca Corwin, associate professor of nutrition. Furthermore, rather than give participants oil supplements, researchers utilized whole food sources of plant-based omega-3s, which include soybean oil, canola oil, flaxseed and flaxseed oil, walnuts and walnut oil.
The 23 study participants, 20 men and three post-menopausal women not on hormone replacement therapy, were fed one of three diets. The first diet was a control diet that mirrored the average American diet and the other two diets were high in plant-based omega-3 polyunsaturated fatty acids.
The two diets high in plant-based omega-3 polyunsaturated fatty acids differed in the amounts of linoleic acid, an omega-6 fatty acid, and alpha linoleic acid, an omega-3 fatty acid, that they contained.
Blood tests conducted during the course of the study found the biomarker for bone resorption, N-telopeptides, decreased significantly during the alpha linoleic acid diet and only marginally during the linoleic acid diet compared to the average American diet. Levels of beon-specific alkaline phosphatases, a measure of bone building, were unaffected by the diets.
"If less bone is being resorbed and the same amount of bone is being created, then there is a positive balance for bone health," Dr. Corwin said.
Some scientists believe the ratio of omega-6 and omega-3 fatty acids is the important factor. The ratio of these fatty acids in the average American diet was about 9.5, while in the linoleic acid and alpha linoleic acid diets it was 3.5 and 1.6, respectively.
The researchers caution that it is unknown if the observed effects are due to increased alpha linoleic acid or conversion of alpha linoleic acid to eicosapentaenoic acid. Fish oils in fish are the main source of eicosapentaenoic acid in the American diet.