Longevity Briefs: The Best Diet To Prevent Cancer?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem: Cancer is one of the leading causes of death worldwide, affecting millions of people every year. Cancer is also a disease of ageing, with many of the hallmarks of ageing being common to both ageing and cancer. 

Despite significant progress, many cancers remain very hard to treat, and even successful treatment of cancer does not reverse the changes that led to the cancer in the first place. Diet and nutrition have been shown to have a significant impact not only in the prevention of cancer, but also the slowing of its progression and the effectiveness of cancer therapy. The question remains: what is the most effective diet for preventing and fighting cancer?

The discovery: A team of researchers conducted a systematic review of 23 studies that investigated the impact of common modern diets on cancer risk and progression. The three diets were: 

• The Mediterranean diet (MD): a diet rich in fruits, vegetables, whole grains, legumes, nuts, fish, olive oil, and moderate wine consumption, with low intake of red meat, dairy, and processed foods.
• The ketogenic diet (KD): a diet high in fat, moderate in protein, and low in carbohydrates. It aims to induce a state of ketosis, in which the body converts fat and protein into carbohydrates.
• The plant-based diet is a diet that excludes all animal products and focuses on consuming fruits, vegetables, whole grains, nuts, legumes, and seeds. 

The studies looked at various cancers and included randomised controlled trials, case-control studies, and prospective/retrospective studies. Almost all included studies agreed that the dietary interventions described above were effective in preventing cancer or slowing its progression, though benefits varied depending on cancer type. The Mediterranean diet was the most studied, and was consistently associated with benefits like smaller tumour size, lower recurrence risk, less DNA damage and less inflammation in cancer patients. Some diets also appeared to enhance the effectiveness of cancer therapy, with one study suggesting that chemotherapy recipients on ketogenic diets had higher survival rates than those receiving chemotherapy alone.

The implications: Dietary interventions may effectively reduce the odds of cancer development and the advancement of diagnosed cancers. The MD was the most extensively studied diet and it showed consistent benefits for a variety of cancer types, though KD and the plant-based diets also showed some promising results for certain cancers. However, diet is a very complex subject to study and it’s hard to conclude based on current evidence that one of these diets is superior. In practice, the best diet often ends up being whichever one is easiest to adhere to.