By Audrey Ho
WE eat to live. We eat to lower our risk of contracting heart disease; we eat to protect ourselves from developing cancer. Suppose we could eat to improve our brain function. Would we?
'Food provides the brain's building materials, cellular energy, immunity function, cognitive reserves and resistance to disease,' said Fernando Gomez-Pinilla, a professor of neurosurgery and physiological science at UCLA Medical School. For him, this 'raises the exciting possibility that changes in diet are a viable strategy for enhancing cognitive abilities, protecting the brain from damage and counteracting the effects of ageing'.
Prof Gomez was in town recently to share his findings at a conference organised by the Singapore Institute of Clinical Studies under A*Star and Abbott Nutrition R&D - on how dietary factors influence brain function. His study was published in the prominent life sciences journal Nature Reviews Neuroscience.
In his analysis, particular nutrients in our diet appear highly beneficial to neurological function. Among them are the famed omega-3 fatty acids.
'About 60 per cent of our brain's building material is lipids (or fats),' explained Prof Gomez. But not all fats are created equal. Of the highest quality is omega-3 fatty acid, with DHA (or docosahexaenoic acid) being the most abundant omega-3 fatty acid in brain cell membranes. 'Omega-3 fatty acids are essential for normal brain function,' he emphasised.
Very simply, neurons in our brain connect via synapses. One way our brain learns is by altering the strengths of the connections between neurons, and by adding or deleting them.
This process is known as 'synaptic plasticity'. Omega-3 fatty acids have been shown to enhance synaptic plasticity. In children, preliminary results from a controlled trial conducted across schools in Durham, UK, suggested better performance when they received omega-3 fatty acids. (However, the results are still subject to scientific scrutiny for validation.)
As the human body is inefficient in synthesising DHA, we are reliant on dietary DHA, said Prof Gomez. Some good sources of omega-3 fatty acids (that include DHA) are fish (salmon, sardines, anchovies), flax seeds, kiwi fruit and walnuts. He advocated getting omega-3 fatty acids from natural whole foods rather than capsule supplements.
A diet low in omega-3 fatty acids has been associated with increased risk of several neurological disorders, including depression, dementia, and bipolar disorder, revealed Prof Gomez. He cited the examples of eastern European nations versus Japan. The former exhibited a strong correlation between low consumption of omega-3 fatty acids and the prevalence of manic depression. On the other hand, the latter demonstrated a relationship between a diet high in omega-3 fatty acids and relatively low incidences of depression.
In stark contrast to the 'good' fats are the 'bad' fats. We know the latter as trans or saturated fats, most often found in junk or fast food. When mice were fed a large amount of saturated fats, lab tests showed a marked decline in the cognitive performance of these rodents. And here's the bombshell: their brains were shown to function at a level 'associated with experimental brain injury'.
Another beneficial nutrient found in Prof Gomez's exploration is folates (or in its synthetic form, folic acid). Folates are found in leafy green vegetables (such as spinach and turnip greens), fruits (such as citrus fruits and juices), and dried beans and peas. Our liver generates folates after the intestine has absorbed vitamin B. A folate deficiency, normally caused by low dietary intake, has been associated with neurological disorders such as cognitive decline and dementia during ageing, he explained. The results of a recent randomised clinical trial indicated that a three-year folic supplementation helped reduce age-related decline in cognitive function.
Never thought antioxidants could affect your neurological function? Well, they can and they do, said Prof Gomez.
Because of its high metabolic load and its abundance of oxidisable material, the brain is prone to oxidative damage. As such, diets high in antioxidants have been made popular due to the positive effects on neural function. Berries, spinach, broccoli and potatoes are all examples of food with abundant antioxidants.
Take vitamin E as an example. This nutrient is plentiful in vegetable oils, nuts, green leafy vegetables and fortified cereals. While it is not well understood how exactly vitamin E can affect cognition, Prof Gomez explained that it is likely to be due to 'the ability of antioxidants to protect the synaptic membranes from oxidation, thus supporting synaptic plasticity'.
Interestingly, the curry spice curcumin has also been shown to 'reduce memory deficits in animal models of Alzheimer's disease and brain trauma'. It has been described as 'relatively non-toxic' and at doses higher than that tested in mice, it has been shown to cause few side-effects. Using India as a case study, Prof Gomez surmised: 'Given the high consumption of curcumin in India, it is possible that it might contribute to the low prevalence of Alzheimer's disease in that country.'
While Prof Gomez's study has shed light on what we know as 'brain food', he is still a strong advocate of nutrients alone being insufficient. A healthy lifestyle of regular exercise, a balanced diet and adequate sleep are all important factors that contribute to optimal brain function and its resilience.
This article was first published in The Business Times.