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In the News: For Brain Function: More DHA, Less Processed Carbs

Importance of the Omega-3s in the Brain

Both of the omega-3 long-chain fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are found in brain tissue, but DHA is the most abundant. DHA comprises about 40% of the polyunsaturated fatty acids (PUFAS) in the brain, and 60% of PUFAS in the eye’s retina.

The level of DHA present in brain cell membranes is affected by the type and amount of fatty acids in our diet. DHA brain levels are also affected by our life stage. DHA is crucial in early life for proper brain and visual development. Studies have shown, for example, that pregnant women who consume higher amounts of omega-3s transfer more DHA to their babies.

While DHA levels increase during infancy and early childhood, those levels decline as we grow older. This has led to ongoing research examining whether higher omega-3 intake can improve memory and learning in healthy, older adults with mild memory complaints.

But if DHA is needed to build cognitive capacity in children and, quite possibly, to support mental ability in older people, could it be of any benefit to younger healthy adults? While some researchers have scoffed at the idea of potential DHA benefits in this “in-between age group”, a new study (1) suggests that DHA supplementation can be helpful in younger people – at least those whose diet is low in this omega-3.

Memory and Reaction Time Improved

For the study, British researchers recruited 176 healthy young adults aged 18-45 years. The participants were assigned to take either placebo or DHA supplements daily for 6 months, and were given a battery of computerized cognitive tests at the beginning and end of the trial.

Both episodic memory and working memory improved for the DHA group compared to placebo takers. However the benefits were more pronounced in women, for episodic memory – the memory of events (times, places, associated emotions and other contextual knowledge). Men, on the other hand, benefited more for reaction times of working memory, an area of short-term memory involved in high-speed processing. Reaction times for men increased by 20% following DHA supplementation.

High Carb Intake Linked to Cognitive Risk

If eating more omega-3 rich fish is a good idea for supporting brain function, consuming fewer processed carbs such as processed grains and sugar is also a good strategy according to new study results (2) from the Mayo Clinic.

The investigators obtained dietary information for over 1,200 people 70-89 years of age, and evaluated their cognitive function. Only the 940 participants who showed no signs of cognitive impairment were tracked. Of those, 200 were starting to show mild problems with language, thinking, memory and judgment about four years later.

They found a significantly higher risk of developing mild cognitive impairment for those who ate the most carbs relative to fat and protein. A diet heavy in sugar also raised the risk substantially.

The researchers emphasize the importance of eating a diet with balanced amount of fats, proteins and carbs. A diet overly heavy in easily digested carbs and sugars might contribute to cognitive risk by impacting glucose (blood sugar) and insulin metabolism. Cognitive deficits and decline have been seen in older people with poor glucose tolerance, and insulin insensitivity and diabetes are risk factors for brain function decline and dementia.

References

1. Stonehouse W et al. DHA supplementation improved both memory and reaction time in healthy young adults: a randomized controlled trial. Am J Clin Nutr [ePub ahead of print March 20, 2013].
2. Roberts RO et al. Relative intake of macronutrients impacts risk of mild cognitive impairment or dementia. J Alzheimers Dis ;32:329-39, 2012.