If your body produces too little lactose, the unprocessed lactose feeds bacteria in the lower gut, causing pain, bloating, flatulence and diarrhoea (more information at allergyuk.org).

Those with higher levels of para-cresol sulphate, made from para-cresol produced by bacteria in the gut, metabolised paracetamol less effectively than those with lower levels.

Previous studies have shown that whole grains can boost bone mineral density, lower blood pressure, promote healthy gut bacteria and reduce the risk of diabetes.