Diets are associated with lifestyle conditions like obesity, diabetes and heart disease. It is often not appreciated that what is eaten has implications not only for physical health, but also mental health.
The brain is the master of the body as it controls almost all bodily function, even when one is asleep. It is very complex, and is believed to be the final frontier of science.
The brain requires nutrients just like the heart, lungs or muscles do. Some foods may increase the risk of neurological and psychiatric conditions like depression and dementia, whereas other food may be protective.
But which foods are important to keep our grey matter happy?
Knowledge about this is still in its early days, but there are research findings that can increase the chances of maintaining a healthy brain well into the senior citizen years.
The brain requires energy for its functions.
As this is dependent on the body's blood flow, it goes without saying that cardiovascular health is crucial for mental health.
An adequate and steady supply of glucose in the bloodstream enhances concentration and focus.
This is achievable with the consumption of wholegrains with a low glycaemic index, ie those that release glucose slowly into the bloodstream, thereby keeping energy levels stable and enabling a person to be mentally alert throughout the day.
Wholegrains with low glycaemic indexes include granary or seeded bread, brown rice or pasta, oatmeal and sweet potatoes.
The body cannot produce essential fatty acids (EFA); therefore, they have to be obtained from food.
The omega-3 fatty acids are essential for health and normal brain function, growth and development.
Research findings have demonstrated that omega-3 fatty acids reduce inflammation and may lower blood pressure, which affects brain health.
They have also been shown to reduce cholesterol and triglyceride levels, the formation of plaques on arterial walls, blood pressure, and abnormal heart rhythms - all of which reduces the likelihood of cardiovascular disease.
The most effective omega-3 fatty acids (polyunsaturated fatty acids) are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Both EPA and DHA are needed for functioning of the brain, heart and joints.
DHA plays an instrumental role in the development of the nervous and visual systems of newborn children.
It is also important for brain function in adults. Low DHA has been found to be associated with an increased likelihood of developing memory loss and Alzheimer's disease.
It has been reported that there is a correlation between fish consumption and lower likelihood of psychotic symptoms. There is also a suggestion that fish oil may prevent psychosis in individuals at increased risk.
EPA and DHA have both been shown to be of benefit in depression and postpartum depression respectively. Conversely, there is a suggestion that omega-3 deficiency may increase the risk of suicide.
The American Heart Association recommends eating fish, especially fatty fish, at least two times (two servings) a week.
Oily cold-water fish like salmon, mackerel, trout, tuna, herring and sardines contain ready-made EPA and DHA for the body to use. Other sources of omega-3 fatty acids include linseed (flaxseed) oil, soya bean oil, pumpkin seeds, walnut oil and soya beans.
Berries contain anthocyanins, which have anti-oxidant and anti-inflammatory properties.
The consumption of blueberries may be effective in delaying or improving short-term memory loss.
Animal studies have demonstrated that a diet of strawberry, blueberry or blackberry extracts lead to a reversal of age-related deficits involving learning and memory.
Other studies have reported that blueberries reduced the effects of Alzheimer's disease or dementia, and improved the learning capacity and motor skills of aging animals.
In addition, it was reported recently in Circulation, a journal of the American Heart Association, that the risk of a heart attack may be reduced by as much as one-third in women who ate three or more servings of blueberries and strawberries per week.
Tomatoes contain an antioxidant called lycopene. It is also a source of niacin, which has been used for years to increase HDL (good cholesterol) and lower LDL (bad cholesterol).
There is evidence that consumption of tomatoes could provide protection against free radical damage to cells that occur in the development of dementia, especially Alzheimer's disease.
Raised levels of homocysteine have been associated with an increased risk of stroke, cognitive impairment and Alzheimer's disease.
A trial in Oxford, England, reported that "the accelerated rate of brain atrophy in elderly with mild cognitive impairment can be slowed by treatment with homocysteine-lowering B vitamins". These vitamins were B6, B12 and folic acid.
They concluded that "since accelerated brain atrophy is a characteristic of subjects with mild cognitive impairment who convert to Alzheimer's disease, trials are needed to see if the same treatment will delay the development of Alzheimer's disease".
The B vitamins are found in high-protein foods like fish, meat, poultry, eggs and dairy, as well as some leafy, green vegetables, beans and peas.
Among the benefits attributed to vitamin C is an increase in mental agility. The sources of vitamin C include leafy green vegetables, cabbage, broccoli, cauliflower, papayas and citrus fruits.
Broccoli is also a source of vitamin K, which is believed to enhance cognitive function.
A report in the American Journal of Epidemiology suggested that an intake of vitamin E may prevent cognitive decline, especially in senior citizens.
It concluded that "decreasing serum levels of vitamin E per unit of cholesterol were consistently associated with increasing levels of poor memory after adjustment for age, education, income, vascular risk factors, and other trace elements and minerals. Serum levels of vitamins A and C, beta-carotene and selenium, were not associated with poor memory performance in this study".
The sources of vitamin E are nuts, leafy green vegetables, asparagus, olives, seeds, eggs, brown rice and wholegrains.
Zinc plays an important role in modulating spatial learning and memory.
But it has to be remembered that dietary fortification and supplementation of zinc could lead to overdose, with consequent toxic effects on brain function.
Animal studies have shown that high dose supplementation of zinc induces specific zinc deficiency in the hippocampus of the brain, leading to impairment of learning and memory.
As such, it is important to keep to the recommended daily allowance (RDA), which varies with age, pregnancy and lactation.
Red meat and poultry are common sources of zinc. Other sources include beans, nuts, seafood like oysters, crabs and lobsters, wholegrains, fortified breakfast cereals, and dairy products.
The relationship between diet and dementia has still to be fully elucidated. However, there are important links that are worth acting on.
A well-balanced diet provides the brain the best opportunity of avoiding disease. If the diet is not balanced for whatever reason, supplements of omega-3 fatty acid, multivitamins and minerals may be useful.
It is advisable to discuss this with the doctor prior to commencing supplements, as excess amounts will lead to adverse effects.
The benefits of a Mediterranean diet have been publicised often. Although there are several countries bordering the Mediterranean, the term commonly refers to the diets of Italy, Spain and Greece.
This diet includes a proportionally high consumption of fruits, vegetables, nuts, wholegrains, fish and unsaturated fats (common in olive and other plant oils); moderate consumption of wine and dairy products like yoghurt and cheese; and low consumption of meat and meat products.
Studies have reported that those on a Mediterranean diet are up to 30 per cent less likely to develop depression, compared to those taking more meat and dairy products.
Consumers of more olive oil have a lower risk of ischaemic stroke, mild cognitive impairment and Alzheimer's disease, especially when they are physically active.
A low to moderate consumption of alcohol has benefits, including improved cholesterol profiles, improved platelet and clotting function, and improved sensitivity to insulin.
A recent meta-analysis reported an association between limited alcohol use and lower likelihood of Alzheimer's disease and dementia.
Moderate alcohol consumption may also protect against cerebrovascular disease with the antioxidants in wine, ie resveratrol, having additional benefits.
However, heavy and long-term alcohol consumption leads to alcohol abuse and dependence, impaired memory, contributes to neurodegenerative disease, and hinders psychosocial functioning.
The Food and Drug Administra-tion of the United States has defined "moderate alcohol consumption" as up to one drink for women, and up to two drinks for men daily.
One drink is equivalent to 12 fluid ounces of regular beer, five fluid ounces of 12 per cent wine, or 1.5 fluid ounces of distilled spirits.
Dr Milton Lum is a member of the board of Medical Defence Malaysia. This article is not intended to replace, dictate or define evaluation by a qualified doctor. The views expressed do not represent that of any organisation the writer is associated with. For further information, e-mail email@example.com. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader's own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.