The link between nutrition and our physical health is well established. Along with a host of nutritional deficiency diseases like rickets or beriberi, it’s common knowledge that, for example, excess salt can lead to hypertension and that a diet high in saturated fat can lead to heart disease. However, the link between nutrition and our mental wellbeing is not nearly as widely accepted or understood.
A familiar scenario: it’s the middle of the week, in the middle of the afternoon. You’re hunched over your desk, squinting at the computer screen and trying to concentrate on that all-important document. You’re trying to push worrying thoughts of sick children or electricity bills out of your mind and attempting to stay alert and focused on the task at hand. Then something happens that immediately perks you up. Your colleague offers you a chocolate/cup of coffee/doughnut and you gratefully accept, knowing that this is exactly what you need to give you a jolt of energy and boost your mood and concentration.
Comfort eating and craving certain foods during times of stress is very common, especially among women. For many of us, it’s an automatic response to reach for those high-carbohydrate and high-fat treats when we’re feeling anxious. But why do we crave these high-calorie foods in particular? Why do we never crave healthy, low-fat foods like fruits or vegetables? Besides the fact that they taste good, research has shown that foods that are high in sugar and fat can actually stimulate the brain’s pleasure centre and also temporarily lower your body’s sensitivity to pain, instantly and physiologically seeming to make you feel better.
A TEMPORARY HIGH
Although these foods may soothe us and provide us with energy in the short term, it should come as no surprise that they can be harmful to us in the long term. High intakes of refined sugar have been implicated in obesity, insulin resistance, depression, fatigue, anxiety and many other conditions. Sugar also uses B vitamins for its breakdown, and this group of vitamins plays an extremely important role in mood regulation.
A cup of tea or coffee has long been offered as a panacea for all kinds of problems, from a failed exam to a broken heart. Having a quick cuppa can lift your spirits and increase your attentiveness, and a major reason for this is the caffeine content. Caffeine mildly stimulates the nervous and cardiovascular systems and increases the heart rate, blood flow, respiratory and metabolic rates for several hours after consumption. It affects the brain and results in an elevated mood and decreased fatigue. While this may sound great, don’t forget that this feeling is short lived and there is no sustainable positive effect on the mood.
THE COLON AND STRESS
The relationship between anxiety or stress and the colon is also well documented. Stress has been associated medically with the derangement of normal bowel function since ancient times.1 There are several theories about the connection between irritable bowel syndrome (IBS) and stress. It is thought that individuals with IBS may be more sensitive to emotional stress, stress and anxiety may make the mind more aware of spasms in the colon, or IBS may be triggered by the immune system, which is affected by stress. IBS, in turn, can affect our eating habits and can also affect the absorption of nutrients from our food, further strengthening the relationship between food and stress.
There is an undeniable connection between what we eat and how we feel, and that relationship works both ways. What we eat affects the way that we feel, and our state of mind, in turn, influences what we choose to eat.
A FOR AMINO ACIDS
Serotonin is a neurotransmitter that carries nerve signals between neurons or nerve cells. A decrease in serotonin levels in the brain can alter your mood, resulting in feelings of anxiety or stress. Serotonin is made from the amino acid tryptophan, which is found in foods such as fish, turkey, chicken, cheese, tofu, oats and eggs. However, eating a meal that is high in tryptophan won’t raise your serotonin levels unless you eat a meal that is relatively high in carbohydrates too, especially unrefined carbohydrates.
B FOR B VITAMINS
Over the past several years, evidence has mounted that B vitamins have an important role in maintaining a healthy mental condition. A Finnish study found that high levels of vitamin B12 in the bloodstream were linked to more successful outcomes among people being treated for depression.
About one-third of depressed patients are shown to have a diet that is deficient in folic acid (also a B vitamin). This deficiency leads to a low serotonin level in the brain. Doses of folic acid can bring serotonin levels back up to normal. In addition, antidepressant medications don’t seem to be as effective if an individual’s folic acid levels are low.
C FOR CARBOHYDRATES AND CHROMIUM
Glucose (from carbohydrates) is the brain’s primary source of fuel, so a reduced carbohydrate intake will reduce the brain’s source of energy. Studies indicate that when people eliminate carbohydrates from their diet, they experience a drop in cognitive skills. Individuals who restrict or eliminate their carbohydrate intake are commonly described as having ‘the Atkins attitude’ – the moody, grouchy or anxious disposition often associated with those on restrictive diets like the Atkins diet.
Carbohydrate-containing foods such as breads, cereals and pasta can produce a temporary increase in brain serotonin and a subsequent calming or anxiety-reducing effect. This explains why people may feel drowsy after eating a large meal of, for example, pasta, since a rise in serotonin can also lead to drowsiness. Carbohydrates affect brain serotonin because they increase the amount of tryptophan in the brain, which is the amino acid precursor of serotonin touched on earlier.
Chromium is a mineral that is vital for keeping your blood sugar levels stable because insulin, which clears glucose from the blood, cannot work properly without it. Chromium has been shown to act as an antidepressant in individuals with ‘atypical’ depression, which is characterised by weight gain, carbohydrate cravings, chronic fatigue and over-sensitivity.
D FOR VITAMIN D
The connection between mood disorders and a vitamin D deficiency is widely accepted. A study at the University of Newcastle in Australia tested the effects of supplemental vitamin D versus placebo in a group of healthy subjects in late winter. The subjects receiving vitamin D had a dramatic improvement in mood scores compared with the placebo group.
E FOR ESSENTIAL FATTY ACIDS
Essential fatty acids (EFAs) are nutrients the body needs but cannot manufacture by itself, and they must therefore be consumed in the diet. EFAs constitute a major part of the lipids (fats) found in the brain and nerves. In recent years, researchers have noted that omega-3 polyunsaturated fatty acids may help protect against depression. This makes sense physiologically, since omega-3s appear to affect neurotransmitter pathways in the brain.
… AND Z FOR ZINC
Low serum zinc levels have been linked to major depression.2 Zinc occurs in very small amounts in the body (it’s a trace mineral), but it assists in the enzymatic reactions in every single cell of the body, making it biologically extremely significant. It’s also known to affect mood, behaviour and learning, among other things.
WHAT ELSE CAN WE DO?
Along with remembering your ABCs and avoiding the usual culprits such as refined sugars and caffeine, there are other ways that you can modify your diet in order to improve your mental wellbeing. One such adaptation is to eat regular meals. The reasoning behind this is that it helps to keep blood sugar levels constant. A drop in blood glucose will inevitably result in a plunge in mood and energy levels.
Other options to explore include the wide array of supplements available for easing anxiety. Herbal products such as gingko biloba, kava, St John’s wort, hawthorn, valerian, chamomile and passionflower are all widely used to manage depression and anxiety, with mixed results.
- Rogers RC, et al. Stress and the colon: central-vagal or direct peripheral effect of CRF? Am J Physiol Regul Integr Comp Physiol 2006; 290: R1535-R1536.
- Levenson CW. Zinc: the new antidepressant? Nutr Rev 2006; 64(1): 39-42.