Nurturing The Brain, Part 7 – Omega-3 Fatty Acidsby Sara Adaes, PhD | November 16, 2015
Omega-3 fatty acids have been highly hyped as being tremendously beneficial to our health. And indeed they are essential for human health.
They are found in high quantities in certain fish, particularly fatty fish such as salmon, tuna, mackerel, sardines, herring and halibut; they are also abundant in certain nuts, namely walnuts, and in whole grains, fresh fruits and vegetables, and edible seeds, particularly in flaxseed, the richest plant source of omega-3 fatty acids.
Although there are many different omega-3 fatty acids, some are considered particularly important for human physiology and health. Alfa-linolenic acid (ALA), which is mainly found in plant oils, is an essential fatty acid because our body can’t synthesize it and it must be acquired through dietary sources. In our body, ALA is converted into eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), which are both also commonly found in marine foods.
Omega-3 fatty acids have become widely popular mainly due to their beneficial cardiovascular effects. And they do indeed affect cardiovascular health in a number of ways: they increase the levels of HDL cholesterol (the good one), thereby decreasing triglycerides in the blood and promoting cardiovascular health; they also lower blood pressure in people with hypertension; they also have antioxidant properties that improve endothelial function and contribute to vascular health.
The anti-inflammatory properties of omega-3 fats also render them effective in many other chronic diseases such as diabetes, asthma, rheumatoid arthritis, and certain types of cancer, for example. And they also have valuable effects on the brain and in brain development.
Omega-3 fats and the brain
Omega-3 fatty acids are highly concentrated in the brain and appear to be important for cognitive and behavioral function. But a bad diet can easily decrease the levels of these molecules. Symptoms of omega-3 fatty acid deficiency include fatigue, memory impairment, mood swings, depression, and poor circulation, increasing the risk of stroke.
It therefore makes sense that counterbalancing these deficits through diet may be beneficial for those same symptoms. And it is.
The vascular effects of omega-3 fatty acids also directly affect the brain by reducing the risk of stroke caused by arterial blood clots. The fatty acid ALA, for example, may be able to aid in stroke prevention and in protecting the brain from its consequences – in animal studies, ALA was able to protect against hypoxic-ischemic injury associated with stroke.
But the effects of omega-3 fatty acids go way beyond vascular health and stroke prevention. They have also been linked to other benefits to brain health, having shown a neuroprotective effect against age-related cognitive decline and dementia.
In fact, reduction of omega-3 fatty acids is one of the normal age-related physiological changes to the brain. Also, lower levels of DHA in the brain of Alzheimer’s disease patients have been reported. Again, counterbalancing these deficits through diet may have a therapeutic potential. The anti-inflammatory properties of omega-3 fatty acids may be the path to their preventive effects on the delay of age-related cognitive decline or in the development of Alzheimer’s disease, at least in early stages of the disease.
A role for DHA in brain repair mechanisms and in neuronal and glial functions that manage synaptic transmission has also been suggested; it has also been implicated in memory formation mechanisms, as well as in neurogenesis in the hippocampus, which helps maintain cognitive function throughout life. Also, ALA has been associated with brain-derived neurotrophic factor (BDNF), a molecule that plays a key role in neuronal maintenance, and in learning and memory.
Omega-3 fatty acids have also been linked to mood control, demonstrating beneficial effects in depression and bipolar disorder. A recent meta-analysis that reviewed data linking fish consumption and depression found enough evidence to state that high-fish consumption can indeed reduce the risk of depression.
This effect could be explained by the fact that fish contain high quality protein, vitamins, and minerals that may help hinder depression. However, omega-3 fatty acids remain the most likely candidates for this effect since they can affect brain membranes’ structure and modify the activity of neurotransmitters, specifically dopamine and serotonin, both associated with depression.
Low levels of certain fatty acids, namely EPA and DHA, have also been found in some children with attention deficit/hyperactivity disorder (ADHD). Clinical studies have demonstrated that children with low omega-3 fatty acid levels had more learning and behavioral impairments and that omega-3 fatty acids were able to improve behavioral symptoms. But conclusive evidence is still somewhat scarce.
Overall, there’s enough evidence showing that omega-3 fatty acids are pretty good for our health. All you need is to follow a healthy diet, rich in fish, nuts, seeds, whole grains, fresh fruits and vegetables, and plant oils – a Mediterranean diet is the key.
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