Written by Marcia J. Egles, MD. When Omega-3 polyunsaturated fatty acid was fed to mice, it altered their gut microbial composition which led to an increased production of inflammation-reducing bacteria and a decreased level of inflammation in the bodies of the mice. Intake of Omega-3 also decreased stress levels and improved cognition in the tested mice.
One of many important nutritional requirements for a developing brain, both before birth and after, is an adequate supply of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs), otherwise known as “essential fatty acids” in mammals. While the Western diet provides an overabundance of omega-6 PUFAs, the omega-3 PUFAs have had a dramatic dietary decline in modern times 1.
A recent study done in mice explores some of the potential interactions between the developing brain and the developing gut, under conditions of omega-3 PUFA deprivation and omega-3 PUFA supplementation. The study found that in mice, brain development and function is highly dependent upon adequate omega-3 PUFA availability in the diet of both the mother mice during pregnancy and throughout the lifespan of the offspring. Additionally, the study investigated a possible mechanism for the effects of the omega-3 PUFAs by examining the development of gut microbes in the mice. 2
In the study, young adult female mice were divided into three groups. One group was fed a standard rodent control diet, one group an omega-3 PUFA deficient diet (O-), and one group an omega-3 supplemented diet (O+). The diets differed only in omega-3 PUFA content. The omega-3 supplemented diet was prepared with microalgal oil rich in eicosapentenoic acid (EPA) plus docasahexanoic acid (DHA), one gram per 100 grams of mouse chow.During pregnancy, the three groups of females were kept on the diets. Their male offspring, 10 per dietary group, were kept with their own mothers until weaning, and continued in their same dietary group throughout adolescence and adulthood.
At 4 to 5 weeks of age, which corresponds to “teenagers” in human years, and at adulthood (weeks 11-13), the three groups of male offspring were subjected to a battery of behavioral tests. Also, stress-induced serum cortisol levels were measured to assess their brain and adrenal function. Markers of inflammation were checked as well. The composition of the varieties of bacteria in their feces was identified by DNA sequencing.
The study found that the mice from the omega-3 deficient group had subtle behavioral problems in early-life and in adolescence; however, the differences were more evident at adulthood. At adulthood, the O- group animals displayed impaired communication and socialization, and increased depressive and anxious behaviors as compared to the control-fed or O+ groups. The omega-3 supplemented group outperformed the other two groups in tests of mouse cognition. The O3 mice also showed a more stable pattern on the stress-induced cortisol tests and less evidence of inflammation.
Microbial analysis of the feces of the groups showed differences in the types of bacterial populations in the guts of the mice. The O+ group showed a greater abundance of fecal Bifidobacterium and Lactobacillus. The feces of the O- mice had relatively more Firmicutes bacteria. Previous studies have suggested an association of Firmicutes in gut microbiota with patterns of brain dysfunction 3-5.
The authors suggest that the neuroprotective effects of omega-3 fatty acids are not solely due to their direct incorporation into neural tissue but through a favorable effect on gut microbiota composition with subsequent improved inflammatory status 1.
Source: Ruairi C. Robertson, Clara Seira Oriach, Kiera Murphy, Gerard M. Moloney, John F. Cryan, Timothy G. Dinan, R. Paul Ross , Catherine Stanton. Omega-3 polyunsaturated fatty acids critically regulate behavior and gut microbiota development in adolescence. Brain, Behavior, and Immunity 59 (2017) 21–37
© 2016 Elsevier Inc. All rights reserved
Posted January 5, 2017.
Marcia Egles, MD, graduated from Vanderbilt University School of Medicine in 1986. She completed her residency in Internal Medicine at St. Louis University Hospital. Dr. Egles is certified in Internal Medicine and is a member of the American College of Physicians. She resides in Avon, IN with her husband and two sons.
References:
- Simopoulos AP. Essential fatty acids in health and chronic disease. The American journal of clinical nutrition. 1999;70(3):560s-569s.
- Robertson RC, Oriach CS, Murphy K, et al. Omega-3 polyunsaturated fatty acids critically regulate behaviour and gut microbiota development in adolescence and adulthood. Brain, Behavior, and Immunity. 2016.
- Bruce-Keller AJ, Salbaum JM, Luo M, et al. Obese-type gut microbiota induce neurobehavioral changes in the absence of obesity. Biological psychiatry. 2015;77(7):607-615.
- Jørgensen BP, Hansen JT, Krych L, et al. A possible link between food and mood: dietary impact on gut microbiota and behavior in BALB/c mice. PLoS One. 2014;9(8):e103398.
- Magnusson K, Hauck L, Jeffrey B, et al. Relationships between diet-related changes in the gut microbiome and cognitive flexibility. Neuroscience. 2015;300:128-140.
