Feeling tetchy? Itching for a scrap? Maybe it's something you ate? I have long believed in "food swings"– ply me with sweets and jam puddings and I'm a different person to my salad-eating alter ego. It's not so much a sugar rush, like the ones that some parents of small children testify to (and which the jury is still out on), but more of a sugar slump.

A growing body of research indicates that what we eat may affect how angry we feel. Yet, for many, the food-mood link still has an aura of quackery. One recent University of California study showed that "greater trans fatty acids were significantly associated with greater aggression," says lead author and professor Beatrice Golomb. "Trans fats interfere with omega three metabolism" – and apparently, the brain's neurons need these essential fatty acids to keep us bright and snappy. Lack of omega three has already been linked with depression and antisocial behaviour, and according to some experts, it seems many of us post-industrialists have woefully omega-three-deficient diets.

It's not exactly "eat a sausage roll; punch someone", but down to "patterns of eating". Another study indicated that when levels of the brain chemical serotonin dip, from stress or not eating, it affects the brain regions regulating anger, potentially resulting in "a whirlwind of uncontrollable emotions".

So why is the food-mood link not more widely accepted? Sketchy evidence, say some scientists. Correlation does not prove causation, for one thing: there's a good argument that someone feeling cheesed off may be more likely to pig out on trans-fat-loaded junk food in the first place. Then there's the contradictory flow of nutritional research, which, thanks to, ahem, "simplistic media coverage" pull us in confusing directions. Take one study that claimed to show that people who plumped for an apple instead of chocolate were more likely to be drawn to violent films. Apparently, exerting self-control led to feeling, well, a bit wound up.

This, of course, puts you in a tricky position. Succumb and eat the sugary snack laced with bad fats and you're hopping mad; resist the urge, eat a carrot instead and you still feel angry. It's an impossible call, and probably accounts for my rather over-complicated personal life. Interestingly, the researchers advise companies to capitalise on this rage by: "advertising anger-themed movies and video games next to healthy food aisles". Talk about spreading the love.

All of this, of course, proves that life is bigger than randomised controlled studies. And that, according to Oxford University's Dr Alex Richardson, who runs the charity Food and Behaviour Research, is precisely why the food-mood case isn't more embraced. "We know the UK diet that is wrecking our bodies is also bad for our brains. We have quite enough evidence, but the scientific community insist on 'randomised controlled double-blind placebo trials' – hard to do, particularly for long periods. Instead, we should look at the totality of evidence."

Artificial trans fats, she says, are particularly pernicious – "research suggests they react with drugs such as repeated amphetamines, increasing the psychotic effects." If you think that won't be a problem for your family, she adds that: "We give very low doses of amphetamines to children with ADHD, in the form of Ritalin." Banned in Denmark, Austria and New York restaurants – with speculations they led to drop in NY crime (the so-called "Twinkie effect") – trans fats are, somewhat bafflingly, still legal in this country, despite being linked to cardiovascular disease and having their use questioned by Nice.

The government however insists on a voluntary approach, pointing to the fact that many major retailers no longer use these fats. "Businesses have already voluntarily reduced trans fats in foods by a third," says a Department of Health spokesman, which sentiment is echoed by the Food and Drink Federation: "Trans fatty acid consumption has fallen from 2.1% of total energy in 1985 to an estimated 0.7-0.8% in 2011 … well below the maximum WHO recommendations. At current levels, they do not pose a health risk."

"This totally misses the point," says Richardson. "There are many people who are still eating loads of trans fats – anyone with a junk diet, including our most vulnerable. Walk down any deprived high street and there will be countless fast-food outlets still using trans fats."

Richardson also points to sugar – fast becoming public enemy number one. "Prison studies suggest that many inmates have poor blood sugar control, compounded by a high-sugar diet. We all know how it feels when blood sugar drops – we feel moody, foggy. Apply that to someone from a disturbed background."

So far, so depressing. So what should we be eating instead – for optimum perkiness? Oily fish, naturally. Oxford criminologist Bernard Gesch found that giving prison inmates a multivitamin and fatty acid supplement led to violent offences dropping 37% compared to 10% for those who were given a placebo – findings that were confirmed by a later Dutch study. Richardson advises a Mediterranean-style diet, while people eating more fruit and veg report feeling calmer, happier and more energetic.

So oily fish, a Mediterranean diet and ample portions of fruit and veg – exactly the diet that is medicine for our bodies is medicine for our brains too. Weird, that. Or not.