Recent studies underscore the importance of diet for the prevention of cancer

By Priyanjana Pramanik, MSc.Reviewed by Lily Ramsey, LLMSep 2 2024

In a recent review article published in Nutrients, researchers summarized the latest evidence on diet and its role in preventing cancer, aiming to update the American Cancer Society (ACS) guidelines.

Their findings indicate that dietary patterns like Mediterranean and vegetarian/pescetarian diets, along with certain nutrient intakes, can reduce cancer risk. In contrast, factors such as excessive fasting and high iron intake may increase it.

​​​​​​​Study: Dietary Interventions for Cancer Prevention: An Update to ACS International Guidelines. Image Credit: Josep Suria/Shutterstock.com

Dietary patterns and cancer risk

Research suggests that time-restricted eating, particularly involving prolonged nighttime fasting and early breakfast, might lower the risk of prostate cancer. This approach to eating could play a role in preventing cancer, though more studies are needed to understand its benefits fully.

In some studies, the Mediterranean diet, known for its emphasis on fruits, vegetables, fish, and olive oil, was linked to a lower risk of lung and breast cancer.

However, the diet’s impact on cancer-related compounds like trimethylamine N-oxide (TMAO) remains unclear, indicating a need for further research to clarify the mechanisms by which this diet influences cancer risk.

Individuals following vegetarian or pescetarian diets were found to have a lower overall cancer risk, particularly for colon cancer, compared to those who consume meat. This suggests that plant-based or fish-based diets might offer protective benefits against cancer.

Low-carbohydrate diets were linked to an increased risk of colorectal and lung cancer but a reduced risk of gastric cancer. This suggests that the impact of carbohydrate intake on cancer risk may vary depending on the cancer type.

High-quality diets, rich in nutrients and low in inflammatory foods, were associated with a reduced risk of certain cancers, such as squamous cell lung cancer.

Conversely, diets with proinflammatory properties were linked to an increased lung cancer risk, highlighting the importance of overall diet quality in cancer prevention.

Specific foods and nutrients

Large-scale studies showed no clear link between dairy intake and breast cancer risk. This suggests that dairy products may not play a significant role in cancer prevention or causation, at least in the context of breast cancer.

No significant associations were found between coffee or tea consumption and prostate cancer risk. Whether these beverages influence other types of cancer is still an open question, but current evidence suggests a neutral effect.

In terms of meat consumption, a large UK study found that a high intake of red and processed meat was associated with a higher risk of lung cancer, emphasizing the potential risks of consuming large amounts of these foods.

The same study also found that diets rich in fruits, vegetables, and whole grains were linked to a lower risk of lung cancer.

Another suggested that phytoestrogens, which are compounds naturally occurring in plants, may reduce lung cancer risk. These findings support public health recommendations to consume a diet high in plant-based foods for cancer prevention.

Micronutrients and heavy metals

The study highlighted conflicting findings regarding iron intake and lung cancer risk. While heme iron (from animal sources) was associated with increased lung cancer risk, non-heme iron (from plant sources) had an inverse relationship, though this was adjusted when considering smoking history. The role of iron in cancer risk appears complex and warrants more investigation.

Exposure to heavy metals like copper, lead, and zinc was associated with an increased cancer risk. Additionally, maintaining adequate levels of certain micronutrients, such as zinc, selenium, and vitamins C and D, was found to lower cancer risk and potentially improve survival in cancer patients.

This underscores the importance of a balanced intake of these nutrients in cancer prevention and management.

Conclusions

The study emphasizes the significant role of diet in cancer prevention, aligning with the ACS recommendations. It highlights the protective effects of the Mediterranean diet, fruits, and vegetables while also noting the potential risks of red meat consumption and high acid load.

The findings underscore the importance of diet quality, particularly in reducing the risk of various cancers, such as lung and breast cancer. However, the study also identifies gaps in understanding the mechanisms behind certain dietary benefits, like the Mediterranean diet’s effect on cancer risk.

The study's strengths include its broad analysis of dietary patterns and cancer risk, offering valuable insights into the benefits of specific diets. However, limitations exist, such as potential bias due to the selection of recent studies and reliance on certain databases, possibly omitting relevant research.

Additionally, diet and cancer are linked in complex ways and influenced by environmental and genetic factors, many of which are partially unexplored.

Future research should focus on understanding the mechanisms behind diet-related cancer prevention, exploring the role of time-restricted diets, alternative diets, and the impact of unprocessed carbohydrates. This could lead to more personalized dietary recommendations and strategies for cancer prevention.