Alzheimer's, Reduced Risk with Higher Blood DHA Concentrations
Having high levels of DHA (docosahexaenoic acid) in the blood can protect against Alzheimer's disease. This news comes from the pages of the scientific journal *Nutrients*, where a group of researchers led by William S. Harris, an expert from the Fatty Acid Research Institute (FARI) and Sanford School of Medicine in Sioux Falls (USA), published a new study on the topic.
According to the data collected by Harris and colleagues, increasing the intake of this Omega-3 fatty acid could be particularly useful for those who carry the APOE-ε4 gene, who are inherently at higher risk of developing Alzheimer's.
Alzheimer's and DHA: The Connection
According to Airalzh (the Italian Alzheimer's Research Association), Italy ranks eighth among the countries with the highest number of people with Alzheimer's. The situation is expected to worsen globally: according to estimates, by 2050, 1 in 85 people will live with this neurodegenerative disease. Diet can significantly influence the risk of Alzheimer's. In particular, DHA, an Omega-3 abundant in the central nervous system and normally consumed through food, can improve several parameters altered by this condition, such as the formation of aggregates that impair neuron function, brain glucose metabolism, and nerve cell inflammation. As early as 2006, a study published in *Archives of Neurology* had linked DHA levels in plasma to a reduced risk of dementia of any cause.
The authors of that study estimated that, on average, consuming 180 mg of DHA per day or eating 3 servings of fish per week can reduce the risk of dementia by 47% compared to individuals with low levels of DHA in plasma. Additionally, past studies have also shown an association between DHA levels in red blood cells (a parameter that better reflects long-term DHA intake than its plasma levels) and cognitive performance and brain volume.
The New Data
In this new research, Harris and colleagues divided the 1,490 individuals involved in the study (men and women aged 65 and older, none of whom had been diagnosed with dementia) into five groups based on their DHA levels in red blood cells. The health of the participants was monitored for an average of 7.2 years, during which neurocognitive tests were also conducted. The data collected showed that:
- when DHA levels in red blood cells exceed 6.1%, the risk of Alzheimer's is reduced by 49% compared to when DHA levels are below 3.8%;
- increasing DHA concentration from below 3.8% to above 6.1% could delay the onset of Alzheimer's by 4.7 years;
- the association between DHA levels in red blood cells and the risk of dementia is stronger in those already at higher risk of developing Alzheimer's because they carry the APOE-ε4 gene.
“Our results,” conclude the researchers, “sugger that increasing DHA intake could be a safe and economically advantageous strategy for preventing Alzheimer's disease in specific populations.”
How to Increase DHA Intake
Omega-3s in food can be found in the form of DHA, EPA (eicosapentaenoic acid, the other biologically active Omega-3), or their precursor, alpha-linolenic acid (ALA).
Unfortunately, the human body has a poor ability to synthesize DHA from ALA; therefore, the best way to increase DHA intake is by enriching your diet with foods that are high in this Omega-3, such as salmon, sardines, and mackerel. In cases of increased need – such as in individuals carrying the APOE-ε4 gene, where DHA levels are lower than average – it may be helpful to use dietary supplements, especially considering that the European Food Safety Authority (EFSA) approves the claim that “DHA contributes to the normal functioning of the brain.” However, caution is advised: the same EFSA emphasizes that, to exert its brain benefits, DHA must be consumed in doses of at least 250 mg per day.
Sources: Sala-Vila A et al. Red Blood Cell DHA Is Inversely Associated with Risk of Incident Alzheimer’s Disease and All-Cause Dementia: Framingham Offspring Study. *Nutrients*. 2022. June 9;14(12): 2408. doi: 10.3390/nu14122408
Airalzh. I numeri. https://cutt.ly/ZJ3fQaV. 13/06/2022
Schaefer EJ et al. Plasma phosphatidylcholine docosahexaenoic acid content and risk of dementia and Alzheimer disease: the Framingham Heart Study. *Arch Neurol*. 2006 Nov;63(11):1545-50. doi: 10.1001/archneur.63.11.1545
Efsa. EU Register of nutrition and health claims made on foods. 13/06/2022
