Alzheimer’s disease (AD) is an advanced stage of dementia which progressively worsens with time and is associated with a high degree of mortality. The disease is not part of normal aging, and is likely caused by various processes that damage nerve cells. Many clinical symptoms are associated with AD, including cognitive decline, memory loss, disorientation, language impairment and so on plus AD also has a pronounced effect on the family or their caregivers. In 2010 in the US alone there were over five million cases and over twenty million worldwide. The cause of AD is not fully known but there
There are many cellular changes that occur as we age, most of which are greatly affected by nutritional imbalances and chronic (even low-grade) inflammation. The brain is most vulnerable to neuroinflammation and oxidative stress, both of which occur more frequently as we age. Other factors such as obesity and type 2 diabetes can accelerate inflammation and aging processes. The presence of diabetes alone doubles the risk of developing neurodegenerative diseases such as Alzheimer’s disease (AD).1
Omega-3 fatty acids are a unique group of polyunsaturated fatty acids (PUFAs) that must be obtained from dietary sources such as fish oil and algae. Their anti-inflammatory and antioxidant effects benefit the cardiovascular system, but also most notably, the brain and nervous system. Higher circulating levels of omega-3s have been associated with a decreased risk of coronary heart disease, breast cancer and cognitive dysfunction (including dementia, AD, and overall aging of the brain).2
Age-related changes in the brain: Inflammation and oxidative stress
Connections between the neurons of your brain can be broken, re-wired, or reinforced, allowing us to learn new information or skills, as well as, memory retention. Learning and memory are highly affected by our diet which directly influences the structure and function of the brain throughout our entire lives.3
There are several processes that occur during aging that increase risk of cognitive decline. These include: neuroinflammation, oxidative stress and damage, and a decrease in the generation of neurons.
In general, we naturally produce greater amounts of pro-inflammatory cytokines as we age, but the choice of dietary fats we consume greatly influence the balance of pro- and anti-inflammatory mediators. For example, diets high in omega-6s and relatively low in omega-3s, which is common of a Western diet, promote a more inflammatory state and have even been linked to cancer.
This problem is accentuated in obese individuals as fat tissue, also known as adipose tissue, can store and be a source of different hormones and signaling molecules. Specific to obese individuals, adipose tissue produces mainly pro-inflammatory cytokines. Released into the blood stream, these compounds can cross the blood-brain-barrier (BBB) and cause inflammation of the brain and subsequent aging. This is in contrast to the adipose tissue on lean individuals which produces mainly anti-inflammatory cytokines.4
As we age there is a notable decrease in the absorption of omega-3s and a decreased ability for these fatty acids to cross the BBB.3 Additionally, we aren’t able to convert shorter chained fatty acids into longer (more beneficial) fatty acids as efficiently. So already we can see that there is a need for increased omega-3 intake as we age.
Oxidative stress also increases with aging, but the presence of antioxidants can help prevent subsequent damage. If oxidative damage accumulates it can lead to “mitochondrial dysfunction” in our cells. This prevents the cell – in this case, our neurons – from being able to properly and sufficiently make ATP energy. The consequence of which is the inability to properly respond when brain cells become injured.4
What are Omega-3 fatty acids and how are they beneficial?
Omega-3 fatty acids have both anti-inflammatory and antioxidant properties. Human trials have shown benefits of omega-3s in maintaining healthy blood pressure, blood vessel function, cholesterol levels, heart rate and management of inflammation.2 The consumption of omega-3s has even been shown to reduce mortality from cardiovascular disease by 19-45%, and reduce the risk of dementia by 40-50%.1
Docosahexaenoic acid (DHA) in particular is known for its role in brain health and protection. This anti-inflammatory and antioxidant fatty acid promotes the production of new neurons and reduces the production and accumulation of amyloid-beta (a compound that in excess can lead to the progression of AD).1
Unfortunately, the average Western diet doesn’t provide enough omega-3s, and this low intake of omega-3s increases the risk of cardiovascular disease and AD, especially in the presence of other negative health factors such as: type 2 diabetes, high blood pressure, high cholesterol, high alcohol intake, low intake of antioxidants, and a sedentary lifestyle.1
Increasing consumption of fish can reduce risk of developing dementia and AD, however, as dietary changes tend to be a challenge for most, supplementing eicosapentaenoic acid (EPA) and DHA via fish oil and algal supplements can provide a solution. Animal studies have shown that supplementing EPA can decrease inflammatory markers in the brains of aged rats. Even just two months of supplementation of both EPA and DHA increased omega-3 levels in the brain and improved spatial memory deficits.3
In humans, a prospective cohort study found that those consuming the highest amounts of dietary omega-3s had a significantly lower risk (18%) of unhealthy aging compared to the group with the lowest consumption.2 This means a greater chance of aging without chronic diseases such as cardiovascular disease, cancer, lung disease, cognitive dysfunction and dementia.
The aging brain is most vulnerable to oxidative damage and low-levels of inflammation, both of which can lead to neurodegeneration and cognitive decline. Diets rich in EPA and DHA seem to protect against this cellular damage, promoting healthy brain function and a healthy cardiovascular system, both of which are at risk of deteriorating as we age.
- Cole GM, Ma Q-L, and Frautschy SA. (2010). Dietary fatty acids and the aging brain. Nutr Rev. 68(0 2): S102-11
- Lai HTM, de Oliveira Otto MC, Lemaitre RN, et al. (2018). Serial circulating omega 3 polyunsaturated fatty acids and healthy ageing among older adults in the Cardiovascular Health Study: prospective cohort study. BMJ. 363: k4067
- Cutuli D. (2017). Functional and structural benefits induced by omega-3 polyunsaturated fatty acids during aging. Curr Neuropharmacol. 15(4): 534-42
- Freitas HR, Ferreira GDC, Trevenzoli IH, et al. (2017) Fatty acids, antioxidants and physical activity in brain aging. Nutrients. 9(11): 1263