A new review published in the journal Nutrition and Health suggests that regular consumption of these popular beverages could significantly raise the risk of alopecia, hair loss from the scalp or elsewhere on the body.

The team, which examined 17 international studies on diet and hair health, emphasised that nutrition plays a pivotal role. “Diet and nutrition play a crucial role in hair health,” they wrote, adding that “vitamin D and iron supplementation, while limiting alcohol and soft drinks, may be beneficial.”

While the analysis does not prove that fizzy drinks directly cause baldness, the evidence points towards a clear link. Sugary and caffeinated drinks were found to affect hair density, growth, thickness, shine and even colour. In one study, individuals consuming more than 3.5 litres a week (roughly 11 cans) were more likely to suffer significant hair loss, especially men.

The biological mechanisms are still being investigated, but scientists suggest that high caffeine can elevate cortisol, the stress hormone, while excessive sugar contributes to poor circulation and inflammation, both of which weaken hair follicles. A lack of protein in the diet was also associated with thinning and lightening of hair.

The concern is particularly relevant to younger men. Research indicates that around a quarter of men in their 20s already show signs of balding, a figure that rises steeply to 85% by the age of 50. A 2023 Chinese study further found that young men drinking sweetened beverages seven times a week are more than three times as likely to experience hair loss.

Portuguese scientists also highlighted a protective role for vitamin D, which appears to reduce the risk of both androgenetic alopecia, also known as hereditary baldness, and alopecia areata, an autoimmune condition that causes sudden patchy hair loss.

Dermatologists caution, however, that baldness is complex and influenced by genetics as well as lifestyles. As Dr Susan Massick of Ohio State University noted, “Male-pattern hair loss is multifactorial.” Still, with younger men increasingly seeking out costly transplants, the research underlines the importance of prevention.

At the same time, hope may be on the horizon: a recent trial of a topical drug, PP405, showed promising results in stimulating regrowth within just eight weeks.

For now, Portuguese researchers advise a simple step: cut down on sugary drinks and keep vitamin levels balanced to give your hair the best chance to stay put.