Diet can play a role. For example the amino acids we ingest will affect the neurotransmitter production in our body. Neurotransmitters can affect various aspects of our mood. For example epinephrine that amps us up. Serotonin that makes us tired and suppresses the appetite. Taurine and glycine that help to calm us. Acetylcholine that helps us remain alert. Dopamine, which gives us that in love feeling.....
And some chemicals in the food can directly affect our mood. Such as the phenylethylamine (PEA) and cannboid like compounds in dark chocolate. And carbohydrates can influence serotonin release.
Then there are the phytoestrogens that help to regulate our hormones. And we all know how unbalanced hormones can cause mood disorders.
Hormones are also regulated through factors such as cholesterol levels, some of which is derived from food. Cholesterol is required form hormone formation. Zinc and B vitamins from food play a role in hormone metabolism, and the fiber we eat feeds the flora that breaks down the hormone metabolites and produces B vitamins for the body.
Estrogen, which antagonizes the androgens (testosterone, progesterone) that can make us aggressive and angry is often found in high levels in beef and dairy. The high fat content and the estrogens in these foods can also lead to weight gain through thyroid suppression, fat cell enlargement and the calorie dense fats in these foods. To make matters worse the increased body fat itself produces even more estrogen.
B vitamins, lecithin and silica also help support the nervous system.
Then there is vitamin C and pantothenic acid in particular are needed for proper adrenal function. And the adrenals help to keep us on an even keel by secreting anti-stress hormones during stressful situations.
On the other hand our attitude can also affect our personality. Stress will atrophy the adrenal glands and can lead to nutritional deficiencies that as we have seen play essential roles in personality.
And as I pointed out the other day some people are addicted to their testosterone rushes. But elevated testosterone can lead to anger issues.