The Mediterranean Diet and Head and Neck Cancer

Head and neck cancers generally involve the moist mucosal surfaces inside the head and neck (such as the mouth, nose, and throat). Cancers of the brain, eyes, esophagus, thyroid, scalp, muscles, and bones of the head and neck are generally not included in this category. Smoking, alcohol, and human papillomavirus (HPV) infection can be considered the 3 most important risk factors for head and neck cancers. At least 75% of cases result from smoking and alcohol use; however, HPV is increasingly important in these cancers. Human papillomavirus (HPV) is a viral infection transmitted sexually and through skin contact, affecting more than approximately 14 million people annually in the United States alone. Nearly half of HPV infections affect the genital area, and approximately 80% of sexually active people may acquire and spread HPV at some point in their lives. Contact between the mouth and a partner’s genitals during sexual activity (oral sex) can transmit HPV to the mouth and throat. HPV is not just one virus. There are approximately 200 types, of which 30-40 infect humans.

Recent studies have shown that HPV causes 25% of head and neck cancers and 60% of oropharyngeal cancers (oral cavity and pharynx).

The relationship between head and neck cancers and diet

Dietary factors and body mass index (BMI) are thought to play important roles in head and neck cancer. Some studies have linked increased BMI with a higher risk. However, only a limited number of studies have investigated the relationship between diet and head and neck cancer.

Canned and salty foods have been identified as risk factors for head and neck cancers. Betel pepper, used in Southeast Asia, should also be recognized as a strong risk.

How should we eat to reduce head and neck cancer risk?

International Journal of Cancer published findings that high dietary fiber intake reduces head and neck cancer risk (see our detailed commentary on the relevant article).

The Mediterranean diet, rich in dietary fiber, is viewed as the healthiest way to eat. We investigated whether Mediterranean-style eating could reduce head and neck cancer risk. Studies generally examined patients’ eating habits and kept food consumption records.

A case-control study in Italy and Switzerland included 768 patients diagnosed with head and neck cancer and a control group of 2078 healthy people. Participants were asked about their eating habits and food intake over the previous 2 years. Greater consumption of fruit, vegetables, legumes, fish, and monounsaturated fats (such as olive and avocado oils), with less dairy and red meat, was associated with reduced risk. The favorable effect of the Mediterranean diet was also stronger in younger people and former smokers.

Another Italian study included 500 diagnosed patients and a control group of 433 people. Participants were asked about Mediterranean diet adherence, smoking, and alcohol intake during the preceding year and were followed for 12 years. The diet was protective against all head and neck cancer types in both sexes. Older age, smoking, alcohol, and red meat increased risk, while vegetables, fruit, and legumes reduced it. A striking finding was that, besides reducing head and neck cancer risk, the Mediterranean diet reduced mortality by 60%.

A meta-analysis of 22 case-control studies found that the Mediterranean diet, characterized by high vegetable and fruit intake and lower red meat intake, reduced head and neck cancer risk. As in other studies, its protective effect was greater in never-smokers than in smokers.

How do foods affect head and neck cancer?

The Mediterranean diet frequently includes vegetables and fruit rich in beneficial micronutrients. Grains, nuts, legumes, fish, and olive oil as the main fat source are used. Red meat and dairy intake is relatively low. Studies attribute the protective role of vegetables and fruit to vitamins C and E and flavonoids. Olive oil, widely consumed in Mediterranean countries, contains antioxidants such as oleic acid, a-tocopherol, and vitamin E and has shown favorable effects in head and neck cancer.

Omega-3 fatty acids, abundant in fish and shellfish, have reduced tumor formation and growth in laboratory mice. Their effect on head and neck cancer is not yet clear. Many studies suggest that fish and shellfish may reduce risk and recommend them as part of a healthy diet. However, numerous recent studies suggest that antioxidants and vitamins provide their desired health benefits when consumed naturally in food as part of a healthy diet, rather than as supplements.

Meat has a relatively unfavorable effect attributed to its fatty acid composition and the presence of nitrites, N-nitroso compounds, heterocyclic amines, and polycyclic aromatic hydrocarbons.

Milk and dairy products, grains, and sugars are other dietary components whose roles in head and neck cancer remain unclear.

The fact that head and neck cancers are less common in Mediterranean countries than in northern Europe may also help explain the role of the Mediterranean diet.

What about the Americas? A long-running study of eating habits and head and neck cancer may provide insight.

This American population study lasted 10 years. Mediterranean diet adherence was assessed from food-frequency records of 494,967 people. They were followed for a long period to see whether they developed head and neck cancer. Cases were reported in 1466 of 295,299 men (0.49%) and 402 of 199,668 women (0.20%).

Food records showed an association between Mediterranean diet adherence and lower head and neck cancer risk in both sexes. Adherents were also more likely not to smoke or drink alcohol. This shows that healthy lifestyle factors, alongside a healthy diet, affect risk. Head and neck cancers are characterized by sex and racial disparities. Men are affected more than women, and African Americans more than White people. Further research is needed to fully explore these differences.

Summary and conclusion

The Mediterranean diet has beneficial roles in many cancers and diseases, and studies have clarified its favorable effect on head and neck cancer somewhat. Smoking and alcohol pose substantial risks; stopping both is the first step in reducing risk. Taking care to avoid HPV transmission and receiving the highly effective HPV vaccine also reduce HPV-related head and neck cancer risk. On June 12, 2020, the US Food and Drug Administration (FDA) approved the nine-valent HPV vaccine Gardasil-9 to protect against head and neck cancers. A healthy diet and avoiding alcohol and smoking are manageable risk factors. They may also help you feel better and keep your body strong throughout life.