Published in the European Journal of Clinical Nutrition, the study tracked the influence of diet on 14,000 British children from birth to adulthood and is believed to be the longest of its kind ever reported.

Using the Avon Longitudinal Study of Parents and Children, the research team found:

• Children who drank fizzy drinks such as cola or sugar-sweetened fruit cordials before the age of two gained more weight when they were 24 years old. Girls who had pure fruit juice gained less weight, while the weight of boys remained the same.
• At three years of age, toddlers who drank cola consumed more calories, fat, protein, and sugar but less fibre. In contrast, those given pure apple juice consumed less fat and sugar but higher amounts of fibre.

The study also highlighted corresponding differences in food choices. Children who consumed pure apple juice often followed a diet with more fish, fruit, green vegetables, and salad, whereas those drinking cola ate more burgers, sausages, pizza, french fries, meat, chocolate, and sweets.

Additionally, the team discovered a link between sugar-sweetened drinks and social deprivation, with children from affluent backgrounds more likely to have access to pure fruit juice.

Lead researcher Professor David Benton said: “The early diet establishes a food pattern that influences, throughout life, whether weight increases. The important challenge is to ensure that a child develops a good dietary habit: one that offers less fat and sugar, although pure fruit juice, one of your five a day, adds vitamin C, potassium, folate, and plant polyphenols.”

Dr Hayley Young added: “Obesity is a serious health concern, one that increases the risk of many other conditions. Our study shows thatthe dietary causes of adult obesity begin in early childhood and that if we are to control it, more attention needs to be given to our diet in the first years of life.”