Updated 25 September 2013

How food affects your mood

The answer to mood swings, irritability and low energy levels may be as simple as the food we put on our plates – and how frequently we eat it.


The answer to mood swings, irritability and low energy levels may be as simple as the food we put on our plates – and how frequently we eat it.

Although this is a new and controversial field, more and more research studies are pointing to the fact that food affects our body chemistry in more ways than previously thought.

"Current research supports the relationship that exists between our diets and our overall mood and energy level," says Dr Bruce Webb, who was recently involved in developing fast-food chain Kauai's range of "mood foods".

"From a dietary perspective, we become what we absorb, which in turn is related to what we eat," Webb, a general practitioner with a holistic approach to nutrition and lifestyle, was recently quoted as saying in a Kauai press release.

Other South African experts agree. Adele Pelteret, a Clinical Nutritionist based in Cape Town, also told Health24 that food plays a crucial role in mood and behaviour. But unfortunately, the typical western diet – which most of us follow – isn't always beneficial.

The importance of whole foods
According to Webb, the western "fast-food" diet involves the use of processed and refined foods from which essential components have been removed. As a result, most people's diets are deficient in essential nutrients and fibre.

"Basically, the food might taste good, but it cannot go the distance when it comes to providing what is needed nutritionally," Webb says. "This predisposes to unstable blood sugar levels and macro- and micro-nutrient deficiencies, which have negative implications for mood and energy."

In fact, research shows that people with thiamine (vitamin B1), folate, vitamin B6, or vitamin B12 deficiencies are at risk for depression. These vitamins and minerals can be found in fresh fruit and vegetables, legumes, meat, fish, poultry, grains and cereals.

Several studies have also linked diets deficient in omega-3 fatty acids, of which fish is an excellent source, to depression and mood swings.

It is therefore crucial to eat more whole foods and to pay specific attention to the inclusion of fresh fruit and vegetables, legumes and fish. Many of us consume too little of these important foods.

When it comes to balancing blood sugar levels, the glycaemic index (GI) is a useful tool. This index classifies carbohydrate foods as "slow"- or "fast-releasing" in terms of glucose, and therefore energy, release.

To balance mood and energy levels better, it's important to eat more of the low-GI, or slow-releasing, foods. Most unrefined carbohydrates, such as fruit, vegetables, legumes and whole-grain foods, fall into this category.

Dieticians generally agree that one should also never skip meals and have one or two healthy snacks during the day to balance blood sugar.

Drink more water
Drinking enough water throughout the day is a key message when it comes to general health. Also in terms of mood and behaviour, sufficient water intake is essential.

According to Pelteret, water helps to eliminate toxins, which can affect mood, and is also important in terms of balancing minerals, kidney function and brain function.

Food intolerances and allergies
Underlying food intolerances and allergies can also play a role in terms of mood and behaviour. This is important, especially as it is estimated that one in every three people has hidden allergies, according to Patrick Holford in The Holford Low-GL (Glycaemic Load) Diet.

Pelteret explains that the gliadin and glutenin components in particularly wheat, for example, can have different effects on mood. Unfortunately, many people are unaware of the fact that they are intolerant to one or both of these proteins, which together form gluten – a better-known component of wheat and other grains such as barley, rye, spelt, kamut, triticale and oats.

She also notes that casein, a protein component in milk, can have a negative effect on the brain. In fact, some parents report that removing both casein and gluten from their children's diets increases attention span, eye contact and general mood while decreasing problems such as tantrums and aggression, according to

It's interesting to note that many children who crave dairy products may actually be addicted to casein, Pelteret says, as it can have an opiate effect on some. Opiates, of which morphine and heroin are prime examples, depress the central nervous system and are highly addictive.

Many people are also unaware of the fact that they're intolerant to salicylates - naturally occurring chemicals in plants - which can also have a negative effect on mood. These components can be found under the skins of many fruits and vegetables. People with salicylate sensitivity may also find it difficult to tolerate aspirin.

According to Holford, allergies can be responsible for many symptoms, especially digestive problems such as bloating and constipation. "These are almost always accompanied by mental and physical symptoms, such as mood changes, chronic tiredness, depression, increased appetite, sleepiness after meals, inability to concentrate and a host of minor ailments," he writes.

The role of heavy metals
Heavy metals, such as lead, mercury and cadmium, can be found in our environment – and are, to a large extent, the result of industrial processes. Through air, water and the food we eat, we are all exposed to heavy metals to some extent.

In recent years, high mercury levels in fish and shellfish, for example, have become a major concern, particularly in the United States. This metal has been linked to premature birth as well as damage to the brains and nervous systems of foetuses and young children.

According to Pelteret, heavy metals can also have a negative effect on mood. "In fact, it can lead to serious delinquent behaviour," she says.

In 1996, Dr Herbert Needleman and colleagues at the University of Pittsburgh School of Medicine reported that even nominal doses of lead, well below those associated with poisoning, can lead to antisocial behaviour, violence and delinquency in young boys.

In her practice, Pelteret often uses hair analyses to test patients for heavy metal toxicity.

A balanced and nutritious diet can help protect against heavy metal toxicity, says Health24's EnviroHealth Expert Olivia Rose-Innes. "With lead specifically it helps to stop it being absorbed into the body in the first place."

PMS and diet
Most women would agree that premenstrual syndrome is a major contributor to moodiness and irritability, particularly in the week prior to menstruation. Here, too, food can play an important role.

In another article on Health24, registered dietician Dr Ingrid van Heerden writes that most women can control their PMS symptoms successfully through certain lifestyle changes, such as diet.

For instance, it could help to eat protein at both lunch and supper, to consume less dairy when you're premenstrual, to reduce fat and sugar intake and to drink eight glasses of water a day. Eating less salt and avoiding caffeine can also be beneficial.

Your favourite foods
And then, of course, simply eating your favourite foods can have a positive effect on mood.

According to the European Food Information Council, it has been shown that eating favourite foods can stimulate the release of endorphins, which are known to enhance mood.

The attractiveness of food is not only related to its sensory properties, experts say, but also depends on how hungry you are, your previous experience of eating the food and the social circumstances in which you're eating it.

Some factors that affect food choices are:

  • hunger;
  • the five senses: taste, smell (aroma), texture (mouth-feel), sight and sound (to a lesser extent);
  • emotions (positive and negative);
  • stress;
  • boredom;
  • habit.

– (Carine van Rooyen, updated March 2013)


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