Can what you eat affect the way you feel? It sounds like a no-brainer. I get grumpy and cross when I’m hungry; I feel better after a healthy meal; I feel a bit sick and guilty after a Christmas session on the Quality Street.
But evidence to show that food significantly affects our mood, much less our mental health, is surprisingly thin on the ground. The evidence that people who eat healthily are likely to have good mental health is there, sure.
However, the studies that show this are notoriously prone to confounding. Healthy behaviour in one area predicts it in another, and reverse causality comes into play. If my mental health is good, I’ll be less likely to comfort eat and more motivated to eat well. If I’m depressed, getting out to the shops to buy fruit and vegetables is a challenge in itself.
The experts I spoke to agreed the evidence is not convincing – but they said this is partly because mood is so difficult to measure, and can be influenced by so many factors that trying to isolate the effect of just one factor is difficult.
Dietary factors likely to affect mood or mental health include eating too little, eating transfats, drinking too much alcohol or too little water. B vitamins and omega-3 fatty acids are also thought to be important for the health of the brain. Most experts advise eating regular meals to keep your blood sugar levels steady.
In fact, a good diet for mental health sounds very much like a good diet for physical health – a varied diet with plenty of fruits and vegetables, wholegrains, some protein including oily fish, and little processed or sugary food. What’s good for the body is likely to be good for the mind.
I took a more in-depth look at food and mental health for WebMD health website, here.