What if you could process information more quickly?
What if there were one simple thing that you could do on a daily basis that could help you achieve both of those things? Who wouldn't want that?
A recent study (Stonehouse et al., American Journal of Clinical Nutrition, doi: 10.3945/ajcn.112.053371, published March 20, 2013) suggests that the omega-3 fatty acid DHA may do just that. This study raised the possibility that DHA might boost memory in healthy young people.
This study was designed to overcome the limitations of previous studies, and it was a fairly well-designed study. The study enrolled healthy adults aged 18 to 45 years from New Zealand who had a low intake of omega-3 fatty acids (<200 mg/day) at the start of the study so that any positive effects of DHA supplementation would be readily apparent. Since previous studies have suggested significant differences in cognitive performance between men and women (Who knew?), this study enrolled approximately equal numbers of men and women and analyzed the effect of DHA on their cognitive performance separately. And finally, because individuals with the apoE4 allele have been shown to be at increased risk for developing Alzheimer's disease, this study also analyzed the effect of DHA on cognitive performance in individuals with and without the apoE4 allele. Then, once the scientists had preselected all of the variables to be analyzed, they performed a preliminary statistical analysis to determine how many subjects they would need in the study to come up with a statistically valid conclusion if there were any effect of DHA on memory in this population.
In the actual study, 176 young healthy adults whose diets were low in DHA were given 1.16 g of DHA per day or a placebo for six months. Compliance was assessed by determining the number of pills left at the end of the study and by determining blood levels of DHA and the other omega-3 fatty acids derived from DHA. At the end of the study the participants were put through a standardized battery of tests to assess mental performance.
The results were indeed different for the men and the women in the study. For the women in the study the primary benefit of DHA supplementation was an improvement in episodic memory (the ability to correctly remember words and pictures they had been asked to memorize a short time before). The improvement was equivalent to the ability to remember one more word or one more picture than the placebo group. For the men in the study the primary benefit of DHA supplementation was in the reaction time required to recall something from working memory. We can think of this as a measure of processing speed. This improvement was equivalent to completing a working memory task 223 ms faster than the placebo group.
The authors pointed out that stratifying their results according to the effects of DHA on memory in men and women was an important improvement over previous studies. If men and women had been considered as a single group for the purposes of this study, the positive effects of DHA supplementation on episodic memory in women would have been offset by the lack of effect in men, and the positive effects of DHA supplementation on mental reaction time in men would have been offset by a lack of effect in women. In that case the conclusion might have been that DHA had no effect on memory and young adults as had been suggested by other studies.
The effect of apoE4 on the data was also interesting. The improvement in mental processing speed was significantly greater for men with the apoE4 allele than for men without that allele.
So what is the bottom line for you?
1) This is the first well-designed study on the effects of DHA on memory in young healthy adults, and it suggests that DHA is likely to be important for mental functioning in adults, just as it is in children. However, like any first study it needs to be repeated with even larger population groups before we can be certain that the promising results suggested by this study are real.
2) In addition, the effects, while significant, are fairly small. For example, the women consuming DHA were only able to remember one more word or picture than those not consuming DHA. And the men consuming DHA only had about a 20% increase in mental processing speed than those not consuming DHA. DHA supplementation is not going to be the secret to aceing the next exam.
3) However, even if DHA is not going to turn you into a mental superman or woman, there are plenty of other reasons for making sure that you have adequate intake of omega-3 fatty acids in your diet - such as heart health, reduced inflammation, lower triglycerides and blood pressure, just to name a few. Just think of improved mental acuity as a possible side benefit of making sure you are getting the omega-3 fatty acids you need on a daily basis.
To Your Health!
Dr. Stephen G Chaney
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.