In the last few years, the herb St John’s Wort (Hypericum perforatum) has received much acclaim as an antidepressant. Several studies prove its medicinal effect, and there is evidence that it is every bit as good an antidepressant as conventional drugs such as Prozac. Yet, while St John’s Wort is clearly a valuable weapon in the fight against depression, the plain and simple fact is that depressed individuals are not suffering from a St John’s Wort deficiency. Recent evidence does suggest, however, that depression can be related to a deficiency of certain nutrients in the diet. Of prime importance here seem to be types of healthy fat found in oily fish such as salmon and trout. Research clearly shows that depressed individuals tend to be low in fish fats, and there is good reason to believe that consuming more oily fish may help stabilise mood and combat depression. It does appear as though fish really does deserve its reputation as the original ‘brain food’.
Although some fats in the diet have been linked to an increased risk of conditions such as heart disease and cancer (such as those found in red meat, dairy products and many processed foods), others appear to have a disease-protective effect. Healthy fats, known as essential fatty acids (EFAs) come in several different forms including the omega-3 and omega-6 type. Many of the foods that we eat in the modern day diet including margarine, oil-based salad dressings and most vegetable oils are rich in omega-6 fats. In comparison, our intake of omega-3 fats tends to be low. A rich natural source of omega-3 fats is oily fish such as salmon, trout, tuna, mackerel, herring and swordfish. These fish contain two main types of omega-3 fatty acid; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Within the body, EPA and DHA are found in very high concentration in brain tissue, and are believed to play an important role in nerve function and mood regulation.
There is a lot of evidence linking depression to omega-3 fat deficiency. One study published in 1996 found that depression was associated with a relative deficiency of EPA. In another study published in 1998, levels of omega-3 fatty acids, particularly DHA, were found to be low in depressed individuals compared to non-depressed subjects. This trend was found again in yet another study published in 1999. This evidence suggests that ensuring an adequate supply of omega-3 fats in the diet is a positive step towards reducing the risk of depression. In addition to consuming oily fish at least twice a week, it can help to supplement with fish oils too. Concentrated fish oil supplements rich in EPA and DHA are available in health food stores. An effective dose in the long term might be 1 g, of fish oil, once or twice a day.
While certain foods can help enhance mood and reduce the risk of depression, others seem to have the opposite effect. The chemistry of the brain is both delicate and finely tuned, and can quite easily be upset by certain foodstuffs. Perhaps two of the most disruptive dietary elements in this respect are sugar and caffeine. At least one study has shown significant and sustained improvement in the mood of depressed individuals following elimination of caffeine and refined sugar. The beneficial effect can be quite delayed, and strict elimination for two weeks is necessary before it is possible to judge any benefit.
Another potent dietary factor in depression is a tendency to run a lower than normal level of sugar in the bloodstream ” a condition known as ‘hypoglycaemia’. While the body can run on a variety of fuels, the brain can only derive the energy it needs for normal function from sugar. If the level of sugar in the brain falls, this can cause quite profound changes in mood, and can be a common trigger in problems such as irritability and depression.
Other common symptoms of hypoglycaemia include fluctuating energy and cravings for sweet and/or starchy foods. Anyone suffering from some form of mood disturbance who is also prone to these symptoms might do well to eat regular meals based around foods which tend to stabilise blood sugar levels such as meat, fish, brown rice, wholemeal bread, wholewheat pasta and vegetables other than the potato. Eating fruit and raw nuts between meals may also help keep the blood sugar level from dropping into the danger zone, thereby helping to maintain mood throughout the day.