This is the third book on food matters by Tim Spector. A medic turned professor of epidemiology, he produced a celebrated long-term study of twins. Then his attention was drawn to food, particularly the task of unravelling the relationship between genes, nutrients and their interactions in the gut. He is especially interested in how the gut microbiome works. Eat more fermented foods, he says. Help the gut by tailoring your diet to what will keep it and you healthy. I once went to a medical conference at which a presentation urged all those working in public health to see the mouth to the anus as a single organ rather than a series of separate ones. I’ve never forgotten that. Spector is a key voice in that school of now-influential thought. The gut is where environment, family history, personal preferences, weight, lifestyle and economic circumstances all meld. Thus, if we want to improve quality and longevity of life – the public health nirvana – we must help people eat the right food at the right moment.

Food for Life is a fascinating tour d’horizon, deftly drawing on recent research. The first part has eleven chapters on the microbiome, the human desire for food, what’s healthy and not healthy, the role of the immune system, whether choice is the best driver (it isn’t), the environmental impact of dietary decisions, the role of cooking, storage and processing, and new hi-tech foods such as meat substitutes and spun foods. These are well written, informative and adequately referenced, despite this being a book aimed at a mass market.

Part two consists of twenty-one chapters, each a succinct summary of a major food category: fruit, veg, legumes (vital for the gut and undercelebrated in modern diets, says Spector, and I agree), rice, pasta, bread and biscuits, meat, fermented dairy products, eggs, herbs, seasonings, oils, sweets and more. I particularly