An omega-3 fat called DHA makes up most of the fat in the brain, and is critical to the function and structure of our brain cells.
DHA is one of the two major “long chain” omega-3 fatty acids (EPA and DHA) found in seafood and nowhere else.
The body has no real use for the “short-chain” omega-3s fat found in some plant foods – called ALA – but can use ALA to make DHA and EPA.
There’s ample evidence that diets high in fish and supplemental omega-3s (especially DHA) promote brain health … as you can see from the many studies covered in the Omega-3s & Brain Health section of our news archive.
Recently, scientists from Tufts University set out to see whether low intake of omega-3s was a risk factor for cognitive decline.
Tufts-USDA study links low omega-3 intakes to greater brain decline
The probe was led by Tufts University scientist Tammy Scott, PhD, working at the school’s USDA Human Nutrition Research Center on Aging.
Her team examined 895 people (70 percent female) participating in the Boston Puerto Rican Health Study, who ranged from 45 to 75 years of age (Scott TM et al. 2014).
The volunteers took brain-function tests at the beginning of the two-year study, and again at the end.
As Dr. Scott said, “The participants were put through memory tests using a list of words, an attention test to repeat lists of numbers forward and backward, and a test of organization and planning involving copying complex figures.” (EB 2014)
The participants were asked about their diets at the outset of the study, in order to estimate their intake of omega-3 fats from plant foods, supplements, and seafood.
On average, the estimated intake of omega-3s among the 895 participants was quite low … a shortage typical of the average American's diet.
The 2010 U.S. Dietary Guidelines recommends eight or more ounces of seafood per week, which translates to about 1,750 mg of omega-3s (EPA plus DHA) per week or 250 mg per day.
Only 27 percent of the participants met or exceeded that recommendation, and the most common source of dietary EPA and DHA was canned tuna.
Results link lack of omega-3s to loss of “executive” functions
The scientists compared the participants’ omega-3 intakes to the change in their brain performance after two years.
The results were adjusted the results to account for the known brain-performance effects of education, lifestyle, health conditions, and calorie and fat intake.
Importantly, the results linked the lowest intakes of omega-3 EPA and DHA to the greatest degree of decline in “executive function”.
Executive function is the set of mental processes that helps connect past experience with present action.
People use it to perform activities such as planning, organizing, strategizing, paying attention to and remembering details, and managing time and space.
Loss of executive function may also results in a weakness with working memory … the system that holds multiple pieces of transitory information in the mind.
Lower intakes of DHA and EPA were not linked to greater decline in longer term memory over the two year period.
Dr. Scott had this to say: “While more research is needed, our preliminary data support previous research showing that intake of these types of fish have [brain] health benefits.” (EB 2014)
More research is always good, but by now it should be abundantly clear that, to enable optimal brain health, Americans need a lot more seafood and/or omega-3 supplements.
- Experimental Biology (EB). Diet Can Predict Cognitive Decline: Preliminary data suggest EPA, DHA remain important nutrients. Accessed at http://experimentalbiology.org/
- Scott TM et al. Lower dietary intake of long-chain polyunsaturated fatty acids predict cognitive decline. Presentation Number 124.4. Experimental Biology 2014, Sunday, April 27. Accessed at http://experimentalbiology.org/
- Tucker KL, Mattei J, Noel SE, Collado BM, Mendez J, Nelson J, Griffith J, Ordovas JM, Falcon LM. The Boston Puerto Rican Health Study, a longitudinal cohort study on health disparities in Puerto Rican adults: challenges and opportunities. BMC Public Health. 2010 Mar 1;10:107. doi: 10.1186/1471-2458-10-107.