A short-term low-calorie diet may do more than help people lose weight. It could also reduce inflammation linked to gum disease, according to new research that is shedding fresh light on the close relationship between oral health and overall wellbeing.

Scientists from King's College London have found that people with periodontitis—a severe form of gum disease affecting millions worldwide—showed lower levels of inflammation after following a fasting-mimicking diet for several months. The findings, published in the Journal of Clinical Periodontology, suggest that lifestyle changes could become an important addition to traditional dental care in the future.

Periodontitis occurs when harmful bacteria trigger chronic inflammation in the tissues supporting the teeth. Left untreated, it can lead to tooth loss. Over the past decade, scientists have also linked the condition to broader health problems, including heart disease, diabetes, and other inflammatory disorders.

The study involved 28 patients recruited from hospitals across Spain. Researchers divided them into two groups. One group followed a fasting-mimicking diet, while the other continued with their usual eating habits. Participants in the fasting group consumed around 1,100 calories daily for two days, followed by 750 calories for three days. A sixth day gradually reintroduced food before normal eating resumed. This cycle was repeated three times over six months.

In labs that analysed blood samples and gingival crevicular fluid—a protective liquid found in tiny spaces between teeth and gums—researchers observed notable biological changes. Patients who followed the restricted diet showed lower levels of inflammatory markers in both blood and gum tissue. Among them was C-reactive protein, a widely used indicator of inflammation throughout the body.

Dr Giuseppe Mainas, first author of the study at King's College London, said, "Our study suggests lifestyle modifications could be important alongside proper tooth brushing for patients.”

The findings are particularly striking because previous research had already linked fasting to lower inflammation elsewhere in the body, but evidence connecting fasting directly to gum disease had remained limited.

According to senior author Professor Luigi Nibali, fasting may help by reducing oxidative stress, a process often described as biological wear and tear that damages cells and DNA. “There may be multiple reasons why fasting is beneficial to gum disease patients. Fasting reduces oxidative stress in the body, a common cause of inflammation, which can damage cells and DNA,” he said.

He added: “Intake of high-calorie foods and refined carbohydrates, for example, in cakes and biscuits, can also cause inflammation – so restricting these foods also reduces oxidative stress in the body. It may also be that fasting has beneficial effects on the microbiome – the body’s community of bacteria that keep it healthy. However, further research is needed to confirm this relationship.”

The study builds on growing evidence that diet influences oral health. Last year, King's College London researchers reported that following a Mediterranean-style diet helped reduce gum disease, while successful periodontal treatment appeared to lower risks associated with diabetes and cardiovascular disease.

Experts warn against interpreting the new findings as a universal recommendation for fasting. Certain groups, including people with diabetes, older adults and those with specific medical conditions, may face risks from calorie restrictions. The researchers themselves stressed the necessity of larger studies before incorporating fasting-based approaches into routine treatment.

"Now that we have established this relationship, we would like to do a larger study before potentially incorporating it into gum disease treatment in the future. Food restrictions may harm patients with diabetes, necessitating tailored advice for specific groups. We are currently investigating how we could implement these benefits in high-risk groups who may not be able to fast,” Dr Mainas said.

For millions living with bleeding gums, loose teeth and chronic oral inflammation, the research offers an intriguing reminder that what happens in the mouth rarely stays there. As scientists continue to uncover links between diet, inflammation and disease, the message is becoming increasingly clear: caring for oral health may begin not only with a toothbrush but also with the choices made at the dining table.