Omega-3 fatty acids
Neurons or brain cells contain high amounts of omega-3 fatty acids particularly DHA. This fatty acid plays several important roles in brain health including controlling inflammation (a known driver of neurodegeneration), influencing brain blood flow, helping lower brain deposition of the toxic protein β-amyloid and maintaining brain volume.
How Much Omega-3 FAs are Enough?
There is broad agreement that the omega-3 FAs in our diet have declined progressively. Our ancient hunter/gather ancestors were estimated to consume 12-15 grams each day, while the current intake is 0.5-1.0 grams. As the importance of these FAs to brain health are appreciated, a question becomes how much is adequate supplementation to restore brain health? Two studies have addressed this question recently.
While it would be ideal to measure these FAs in brain cells directly, this is not possible. Typically, the levels in red blood cells are measured and thought to closely reflect brain cell levels. The first study compared SPECT scans which show brain perfusion or blood delivery to different brain areas compared to the red blood cell levels of omega-3 FAs.(1) Higher red blood cell omega-3 levels correlated with higher profusion of several brain areas involved in cognitive processing.
The study went a step further also correlating the omega-3 levels in red blood cells to neuropsychological testing. Higher red blood cell levels of omega-3 FAs correlated with better scores on measures of depressive tendencies. This is important as depressive tendencies both are a risk factors for Alzheimer’s, and they are also caused by the disease itself.
Another recent study also compared red blood cell omega-3 FA content in subjects with minor cognitive impairment (MCI) or Pre-Alzheimer’s disease to similar aged cognitively normal individuals.(3) The MCI group had lower levels of total omega-3 FAS and particularly of DHA. The researchers concluded that the lower omega-3 FA levels might be predictive of the development of MCI or Pre-Alzheimer’s given this relationship.
While multiple studies have found that higher levels of omega-3 FAs correlate with improved brain function and cognition, perhaps the most striking finding has been that omega-3 FA levels directly correlate with the loss of brain volume associated with Alzheimer’s disease. Many of the pathological changes in the brain that are associated with Alzheimer’s disease such as the build-up of the toxic protein β-amyloid show up many years before cognitive function declines resulting in the symptoms such as memory loss. The one finding that is the exception to this is brain volume. Symptoms typically correlate with the loss of brain volume as seen on MRI examination.
Two studies have looked at omega-3 FA levels in older adults compared to brain volume loss.(2, 4) In a study of 1100 postmenopausal women it was found that for each 1 standard deviation higher of red blood cell omega-3 FA levels, the key brain memory area called the hippocampus was 50 mm3 greater. Women in the lowest 20% of omega-3 levels had hippocampal volumes 159 mm3 smaller than those in the highest 20% of the group.
So, how much omega-3 FA intake is enough? This is best determined by a simple test measuring red blood cell levels. The data indicates that the omega-3 FAs should account for >10% of the total red blood cell fatty acid levels. Because of variations of absorption of fatty acids in the digestive tract and transport into cell membranes, different persons will require different supplemental amounts.
The process should begin with a red blood cell omega-3 test. A targeted level of supplementation is started, and the test is redone in about 4 months. Supplementation levels are then adjusted from there to obtain and maintain the >10% level.
An important fact not to get lost here is that the best time to give attention to omega-3 FA levels is prior to the development of the disease as it appears to be preventative. However, even when symptoms have developed optimizing levels of these important fatty acids is an essential part of treatment.
1) Amen et al. QUANTITATIVE ERYTHROCYTES OMEGA-3 EPA AND DHA LEVELS ARE RELATED TO HIGHER REGIONAL CEREBRAL BLOOD FLOW ON BRAIN SPECT. Journal of Alzheimer’s Disease, 2017.
2) Tan et al. RED BLOOD CELL OMEGA-3 FATTY ACID LEVELS AND MARKERS OF ACCELERATED BRAIN AGING.
3) Yuan et al. THE ERYTHROCYTE FATTY ACID PROFILE AND COGNITIVE FUNCTION IN OLD CHINESE ADULTS. Nutrients, 2016;8:385.
4) Pottala et al. HIGHER RBC EPA AND DHA CORRESPONDS WITH LARGER TOTAL BRAIN AND HIPPOCAMPAL VOLUMES: WHIMS-MRI STUDY. Neurology, 2014;82:435-442.