Almost half (49 per cent) of people now avoid foods containing antibiotics or hormones, while 45 per cent opt out of eating artificial additives and 42 per cent have rejected sugar.
More than a third, 35 per cent, of respondents to Nielsen's survey said they avoid sodium, while a smaller amount, 16 per cent, have committed to shunning gluten.
Much of this is driven by a desire to limit less healthy ingredients, with a fifth of Britons saying their choices were an attempt to stave off conditions such as obesity or diabetes.
However, one in five households now also contains someone who suffers from a food allergy or intolerance, Nielsen found.
The most common ingredients avoided in the UK for these reasons are grains (43 per cent), eggs (38 per cent) lactose and dairy (36 per cent) and gluten (30 per cent) — although the jury is still out on whether gluten sensitivity is becoming a more prevalent phenomenon, as the number of gluten allergy (coeliac disease) sufferers has not spiked in recent years.
In response, sales of “free from” products have risen 19 per cent in the last year to £754m annually and could be as big as the mineral water category within two years.
"It’s one of the fastest growing categories and, consequently, supermarkets are extending ranges," said Mike Watkins, Nielsen's UK head of retailer and business insight notes.
"If this growth rate continues, "free from" would be a £1bn market within two years – the same size as today’s mineral water market."