Taking supplements of DHA omega-3 fatty acids results in a significant cardioprotective benefit both for patients at risk of developing cardiovascular disease and in healthy subjects, according to new studies presented at the American Heart Association's scientific sessions this week.
Three new studies back the already significant evidence to support supplementation with docosahexaenoic acid (DHA). Recent advances in measurement techniques have helped to better evalute the effects of omega-3s on lipid profiles.
Researchers from the University of California, San Francisco (UCSF), said on Wednesday they had found that docosahexaenoic acid (DHA) altered the lipid profiles of both children with high cholesterol and mildly overweight men and women, reducing the at-risk populations' chances of heart disease. DHA supplements also improved cholesterol in healthy adults.
In the first randomised crossover study, 20 children with high cholesterol were enrolled to receive nutritional counseling for six weeks and were randomly assigned to receive either a placebo or 1,200 mg daily of Neuromins brand DHA, manufactured from a vegetarian source by Martek Biosciences, for another six weeks after the education.
Data indicates that DHA supplementation resulted in a significant reduction in patients' levels of small, dense LDL particles - known to be highly correlated with CHD. DHA supplementation also significantly increased large, buoyant LDL particles, which pose little to no cardiovascular risk. In addition, while the overall level of HDL for patients receiving DHA was unchanged, researchers noted a favourable increase in large, buoyant HDL particles in this population.
"Our results demonstrate the remarkable role that DHA supplementation can play in improving children's lipid profiles; possibly decreasing their risk of developing CHD later in life," said lead investigator Marguerite M. Engler.
In a further study the investigators randomly assigned 41 mildly overweight men and women to receive an orange drink with or without 1,500 mg of DHA daily for 12 weeks. They reported that while patients receiving DHA supplementation experienced a 7 per cent increase in total cholesterol, this rise was attributed to a dramatic 53 per cent increase in large particle HDL cholesterol.
Additionally, patients' total number of LDL particles did not change with DHA supplementation; however, their levels of small particle LDL decreased by 75 per cent. Overall, patients receiving DHA supplementation experienced a 9 per cent increase in total HDL, an 11 per cent increase in LDL and an 11 per cent decrease in triglyceride levels.
"DHA in a dose of 1,500 mg per day produces a dramatic reduction in small particle LDL cholesterol, a marked increase in large particle HDL, and a significant increase in LDL particle size. Given that these three parameters have a stronger association with CAD events than LDL cholesterol, a cardioprotective benefit of DHA alone may exist via changes in lipid metabolism and needs to be evaluated further," concluded Thomas Barringer, lead investigator and Clinical Associate Professor from the Carolinas Medical Center.
A third study, presented earlier this week, found that 1,000 mg of DHA omega-3 fatty acid daily can favourably impact lipids and reduce cardiovascular disease risk factors in healthy adults.
A researcher from the University of Maryland enrolled 96 healthy adults with normal cardiovascular profiles in the study, randomly placed into four treatment groups. Three groups took a daily dose of 200 mg, 600 mg or 1,000 mg of Martek's Neuromins DHA and the fourth group took a placebo. Patients' lipid levels were measured at the outset of the trial and again at two and four weeks of supplementation.
Patients receiving DHA experienced a 5 per cent dose-dependent increase in HDL cholesterol, with maximum effect occurring with 600 mg per day. Additionally, DHA supplementation resulted in a dose-dependent decrease in patients' triglyceride levels, with a maximum 13 per cent reduction occurring with 1,000 mg per day, also helping to reduce a person's risk of heart attack.
DHA supplementation at 600 and 1000 mg resulted in an overall 5-8 per cent increase in LDL cholesterol, largely attributed to a 28 per cent increase in large, buoyant LDL particles, which pose little to no cardiovascular risk to patients. At the same time, there was no increase in small, medium or total LDL particles, which are associated with low levels of HDL cholesterol, high levels of triglycerides and increased risk of cardiovascular disease.
"This study suggests that 1gram of DHA per day may lower triglycerides and raise HDL cholesterol by increasing the large protective HDL particles," said lead investigator, Harry Oken, clinical associate professor of medicine at the University of Maryland. "This study corroborates other research indicating that DHA may promote cardiovascular health."
Henry Linsert, chairman and CEO of Martek, added: "Martek believes this study clearly indicates that DHA is the ultimate omega-3 fatty acid for patients seeking improved heart health."
The company develops and sells products made from microalgae, including DHA and arachidonic acid, and has recently received novel foods approval in Europe. It has begun marketing its products for use in supplements.