Depression is assuming epidemic proportions and Prozac sales are booming. In the midst of this climate of patient distress and drug bonanzas, a key fact about depression is being overlooked. If the diet of depressed people were to be examined, one would find it far from adequate. People are making bad food choices and selecting foods that actually contribute, biochemically, to depressive states.

While many people understand the connection between nutrition and a physical disease state, fewer people are aware of the connection between nutrition and depression. Depression is more typically thought of as strictly emotional or biochemical.

Nutrition, however, can play a key role, both in the onset, severity, and duration of depression. Many of the same food patterns that precede depression are the same food patterns that occur during depression. These may include skipping meals, poor appetite, and a desire for sweet foods.

Let's take a look at some specific factors:

Omega-3 fatty acids: a safe, natural mood stabiliser?

For years, scientists had wondered why Greenland Eskimos had such a low incidence of heart disease, despite a diet of seal blubber and other high-fat foods. Studies eventually discovered the reason: they eat a lot of fish rich in compounds called omega-3 fatty acids, a "good" fat with cardioprotective effects. Now, compelling new evidence suggests these fish oils may be providing another benefit as well — keeping the Eskimos even-tempered and in high spirits.

Some researchers have found that the omega-3 fatty acids in salmon, mackerel, tuna, sardines, and other deep-sea, cold-water fish may have a profound effect on mood.

No one knows exactly how the omega-3s may regulate mood. One theory is that they work like lithium and certain other standard drugs by dampening overactive nerve-to-nerve communication channels in the brain. Another theory is that we are simply replacing what's missing in the Western diet. More rigorous trials of omega-3s for certain forms of depression are under way and will shed further light on this fascinating relationship. Meanwhile, these researchers feel that in mild cases of depression, there is very little to lose and everything to gain, by supplementing with omega-3s.

Unlike Prozac and other anti-depressants that can cause sexual problems and other disturbing side effects, fish oils appear to cause nothing more serious than occasional indigestion. They are also compatible with most prescription medications, although people taking blood-thinning drugs, such as aspirin or warfarin, should watch out for excessive bleeding since fish oils appear to have an anti-coagulant effect.

Does iron play a role?

Women experience more depression during their childbearing years. And about one in five women of childbearing age has low iron stores, compared to one in 60 men. Furthermore, twice as many women as men are clinically depressed, according to standardised tests. This gender difference begins in adolescence and is more pronounced among married women aged 25 to 45 with children.

Researchers have postulated that this phenomenon is related to marginal iron levels, since iron deficiency has been known to cause fatigue and depression.

Studies on the question have tended to go both ways, but further research is necessary before any conclusions can be drawn.

Low-carbohydrate diets

People who follow extremely low carbohydrate diets run the risk of feeling depressed, because the brain chemicals that promote a feeling of wellbeing, tryptophan and serotonin, are triggered by carbohydrate-rich foods. In fact, anti-depressant drugs like Prozac also target serotonin production.

How and which carbohydrates affect mood and depression is not very clear. And some people tend to be more sensitive to the quality and quantity of carbohydrates eaten.

High glycaemic index (GI) carbohydrates — those converted to glucose very rapidly, primarily sweets, tend to provide immediate, but temporary relief. Once the benefit is gone, you may go looking for more foods to bring up your mood and energy level.

Low GI carbohydrates — converted to glucose relatively slowly, such as whole grains, pasta, and some fruits and vegetables, are more likely to supply a moderate, but lasting effect on brain chemistry, mood, and energy level. For a list of the glycaemic index factor of carbohydrate foods click here.

Vitamins and minerals

Depression has also been linked to a lack of certain vitamins, especially the B vitamins, which are used in nervous system function. Many women do not get enough vitamin B6 in their diets. A less than adequate intake may produce subtle changes in mood, even before a deficiency could develop. Vitamin B6 also plays a role in the brain chemical production of serotonin. Some studies have shown that people who are depressed have low levels of B6 and serotonin. Certain drugs, such as hormone replacement therapy, oral contraceptives, and anti-tuberculosis medication can interfere with the body's use of B6, creating a borderline deficiency.

Other B vitamins also participate in mental health:

• Folic acid deficiency can cause personality change and depression. Folic acid deficiency is a relatively common vitamin deficiency. Not only is it easily destroyed by cooking, but it is most abundant in leafy green vegetables, an often under-consumed food group.
  
• Vitamin B12, at just marginally low levels, can contribute to depression and memory problems. As we age, vitamin B12 may not be absorbed as readily, even if the recommended daily requirement is met through the diet. Vegetarians are also at risk for a Vitamin B12 deficiency.

Minerals that play a role in the development or prevention of depression, irritability, and mood swings include calcium, iron, magnesium, selenium, and zinc.

Low cholesterol: a causal factor?

Rapidly accumulating evidence suggests that low or lowered cholesterol may be associated with increased non-illness-related deaths, such as suicide, brought on by changes in the brain’s biochemistry. In other words, if you have too little cholesterol in your blood, you may be subject to depression. This is because cholesterol is needed to produce a cascade of crucial hormones (including pregnenolone, testosterone, progesterone, estradiol, estrone, and cortisol, among others) and hormones strongly influence mood. Cholesterol also assists in the absorption of essential fatty acids.

Conclusion

The bottom line is that food plays a key role in maintaining mental health. We should:

• Focus on a well-balanced diet, including plenty of leafy greens for folic acid, and bananas, avocado, chicken, greens, and whole grains for B6.


• Eat at least three times a day, including breakfast, with regular snacks.


• Eliminate caffeine-containing foods and beverages as much as possible.


• Replace sweets with different varieties of fruit.


• Drink plenty of water — 6-8 glasses per day.