A diet followed by 4 in 10 young people could be a 'ticking time-bomb' for bone problems

About 5 percent of the UK population is lactose intolerant. Just 1% has celiac disease, meaning they cannot eat gluten, which is found in wheat.

Despite these relatively small numbers, gluten and dairy have been labeled as "bad" or "dirty" by diet trends such as "clean eating."

In general, a "clean" diet means cutting back or eliminating gluten, dairy, processed foods, and refined sugars.

These fad diets are particularly popular with young people, especially women. This year, the Food Standard's Agency's Food and You survey found that almost half (46%) of people aged 16 to 24 said they had a bad reaction to milk, which could be part of the reason for trying out the "clean" way of life.

However, what many people think is a healthy choice could be doing more harm than good.

RELATED: Some of the healthiest vegetables

The National Osteoporosis Society (NOS) has said cutting milk out of diets could be leaving thousands of young adults with weakened bones because they're not getting enough calcium. The charity warned it is a "ticking time-bomb" for developing permanent bone problems like osteoporosis, because bones generally stop developing once you hit 30 years old.

Osteoporosis currently affects about three million people in the UK, and it is usually a normal part of getting older, but if this trend continues a larger proportion of young people now could end up with it.

The risks of "clean eating"

Food bloggers and Instagram chefs promote "clean eating" diets as healthy. They can be, if you ensure to get all the necessary nutrients elsewhere, like calcium from leafy greens and nuts. However, it often doesn't work out in reality.

Young people who don't have the budget to afford nutritionists and expensive health foods look to social media stars for advice on what they should cut out, not add in. Instead of making them healthier, these diets can just end up being restrictive.

Clean eating has faced a backlash in the past couple of years for promoting an unhealthy body image and making people, particularly young people, feel bad about enjoying all types of food. Nigella Lawson, for example, has spoken out against the fad in the past, saying people use it as a way to hide eating disorders.

Ella Mills, the star behind the Deliciously Ella blog, used to be part of the clean eating trend, but has since removed the phrase from her website. However, she claims milk can cause calcium loss in bones, a myth that crops up on food blogs and healthy eating websites over and over again.

This also isn't the first time clean eating diets have been described as potentially dangerous. In 2016, experts said restrictive diets were a noticeable route into eating disorders for vulnerable people.

However, the damage has been done. The NOS survey found that four in ten young people (18 to 24) have tried a clean eating diet, and one in five have reduced how much milk and cheese they consume. The issue isn't necessarily choosing to be healthier, it's following the advice of people who have no real authority to talk about nutrition.

Professor Susan Lanham-New, an adviser to the NOS and head of nutritional sciences at the University of Surrey, told Today on BBC Radio 4: "There's nothing wrong with the concept [of clean eating] but I think there is very much a focus for young people to cut out dairy. Social media is rife with people who are talking, quite frankly, about subjects where they don't know what they're talking about."

"The foundations for good bone health are very much laid down in the early years, up to the late twenties," she added. "If you have a prolonged time of low calcium intake, that will put you at risk of osteoporotic fractures in later life and at greater risk of stress fractures in earlier life."

SEE ALSO: I tried a meal subscription box for 2 months — here's the hack I used to eat healthier and save money afterwards

NOW WATCH: Winter Storm Stella could turn into a 'weather bomb' — here's what that means