Plant-based omega-3 polyunsaturated fatty acids (PUFA) may have a protective effect on bone health, according to a team of Penn State researchers who carried out the first controlled diet study of these fatty acids contained in such foods as flaxseed and walnuts.
Normally, most of the omega-3 fatty acids in the diet are plant-derived and come mainly from soybean and canola oil. Other sources are flaxseed, flaxseed oil, walnuts and walnut oil. Smaller amounts also come from marine sources, mainly fish, but also algae. Omega-3s are thought to have an anti-inflammatory effect and may play an important part in heart and bone health.
"The unique thing about this study is that we know exactly what the participants ate because we closely controlled their food," says Dr. Rebecca Corwin, associate professor of nutrition. "These people are really dedicated to spend a total of 24 weeks in the study with 18 weeks eating only what was supplied to them."
Previous studies of omega-3s on bone health used oil supplements rather than whole food sources. The researchers note in a recent issue of Nutrition Journal, that "supplement studies typically do not involve control of the background diet, and it is possible that differences across studies could be explained by failure to control for other nutrients that affect bones."
The researchers developed three diets that they fed sequentially to the 23 participants. Twenty of the subjects were men and three were postmenopausal women not on hormone replacement therapy for six months. This study was part of a larger one investigating the effects of omega-3 fatty acids on cardiovascular health. For six weeks the subjects ate either the control diet, dubbed average American diet or two other diets high in PUFA. After six weeks the group had three weeks off to resume their typical eating pattern and then for the next six weeks they ate one of the other diets. This continued for 24 weeks until all
Contact: A'ndrea Elyse Messer