We all know some of the not-so-old wives tales about how food affects our mood. Perhaps it's the stimulating effect of the day's first double espresso, the contentment you feel after eating bangers and mash, or the simple fact that chocolate makes your world go 'round.
Research suggests that any direct hormonal link between the food that gets our mood going and the subsequent happiness is small, if it exists at all.
One possible link between what we eat and how we feel could be the effects of food on particular hormones. The chemical messages contained in some hormones, such as oestrogen or testosterone, have strong effects on our moods, so any potential changes in the levels of those hormones prompted by what we eat, could muddle our moods.
Recently Italian researchers found that two of the thousands of food additives used around the world can mimic the properties of oestrogen hormones, which are sex hormones that affect fertility as well as moods. The researchers found propyl gallate (a preservative for fats and oils) and 4-hexylresorcinol (used to maintain the appetising colour in seafoods) fitted to oestrogen receptors under laboratory conditions.
But CSIRO nutritionist Dr Peter Clifton says that demonstrating oestrogenic properties in a test tube is very different from demonstrating them in a living, breathing body. He found that most of the compounds for oestrogenic activity are very poorly absorbed. Thus, it is unlikely to have any hormonal effect on the way we feel or act.
It's a similar case for the naturally-occurring oestrogenic compounds in our food such as isoflavones - found in plants such as red clover and soy. Red clover contains particularly high levels of these compounds, which affect the fertility of animals such as cows and sheep when eaten in large quantities. But these foods don't affect our hormone levels as we don't absorb the isoflavones in the same way cows and sheep do.
In any case, Clifton points out isoflavones are only very weak oestrogens.
The joy of eating
Rather than the actual make-up of the foods we eat affecting our hormones and our moods, it's the act of eating itself prompts the release of a range of hormones. Eating has a strong effect on the production of insulin, which is produced when we eat carbohydrates, but there is no research linking it to mood changes.
In the end, Clifton says there's no research to suggest that the foods we eat have hormonally-based effects on our moods.
But there are other components of food that can affect your mood such as tryptophan, an amino acid found in some form of nuts, poultry and dairy. Your brain uses tryptophan to create the neurotransmitter serotonin (known to improve mood).
Clifton also says certain foods make us happy because we have developed a partial addiction to them, such as the chocolate we eat in the afternoon or the morning coffee that gives us a buzz.