Enriched soybean oil may be a sustainable alternative to fish oil for obtaining heart-healthy omega-3s, suggests a new Monsanto study.
Based on more than 250 volunteers, company researchers found that plant-based soybean oil containing stearidonic acid (SDA) raised blood-cell concentrations of eicosapentaenoic acid (EPA), one of two main omega-3 fatty acids that have been shown to reduce the risk of cardiovascular disease.
Monsanto, an agricultural biotechnology corporation, is currently developing an SDA-enriched soybean oil under the brand name Soymega.
"We know consumers aren't getting adequate amounts of long chain omega-3 fatty acids in their daily diets," lead researcher Shawna Lemke of the Monsanto Company, in St. Louis, said. "In addition, nutritionally efficient sources of dietary long chain omega-3s are today limited to seafood and supplements."
Three supplements daily
Lemke and her team randomly assigned 252 overweight, non-fish-eating people between the ages of 25 and 35 to consume one of three supplements daily: unfortified soybean oil, SDA-containing soybean oil or EPA fish oil.
The oils replaced other fats in the participants' diets, and were supplied in one-gram capsules as well as 14. 7-gram packets for daily use in salads and cooking.
Over the next three months, the researchers monitored the omega-3 content in participants' red blood cells. Higher levels have been shown to protect against sudden cardiac death.
The EPA fish oil and SDA-enriched soybean oils raised these levels by nearly the same amount - both significantly more than the non-enriched soybean oil, report the researchers in The American Journal of Clinical Nutrition.
The control group
Participants in the control group had received regular soybean oil in both capsule and packet form, others got either 1g of EPA fish oil in capsules plus regular soy oil in the packets or 1g of regular soy oil in capsules and 14. 7g packets of SDA-enriched oil.
Given the different dosages of fish oil and SDA-enriched oil used in the study, the researchers estimate that five- to six-times as much enriched soybean oil was needed to achieve the same effect as the EPA fish oil.
The researchers found no side effects related to consumption of the SDA-containing soybean oil.
"This study confirmed that SDA is efficiently converted in the body to heart-healthy EPA," said Lemke.
Easier to incorporate omega-3s into everyday foods
"A plant-based source of omega-3s makes it easier for food companies to incorporate omega-3s into everyday foods," she added, noting that other plant-based sources, such as alpha-linolenic acid (ALA), have not yet shown such efficient conversion to EPA.
Penny Kris-Etherton of The Pennsylvania State University, who was not involved in the study, also sees promise in SDA: "Stearidonic acid is an environmentally friendly way to consume long chain omega-3 fatty acids. That is, there will be less of an impact on the fish stores in the oceans, lakes and rivers."
She did note one disadvantage: Stearidonic acid is not converted to docosahexaenoic acid (DHA), the other key omega-3 fatty acid that is known to be heart-healthy. DHA is present in fish oil. However, prior research has shown that EPA alone can reduce the risk of cardiovascular events.
SDA-enriched soybean oil not to be used in moderation
"I know of no reason why (SDA-enriched soybean oil) shouldn't be used in moderation by healthy individuals," Kris-Etherton said, noting that this could include women at risk for breast cancer who are typically told to avoid soy products because of their potential hormone-mimicking effects. "But too much oil will cause weight gain and make it difficult to achieve nutrient adequacy."
Based on current data, the Monsanto researchers estimate that consuming about one and a half grams of SDA would help the average American increase their omega-3 intake to meet the equivalent of the American Heart Association's recommendation of "at least two, preferably oily, fish meals per week."
Monsanto expects its Soymega oil to be approved for sale sometime in 2012. Other companies are also working to develop SDA- or EPA-enriched oils to be used directly by consumers or incorporated into processed foods. (Reuters Health/ September 2010)
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