- A study from the University of Oxford indicates that diets excluding or limiting meat are likely related to reduced cancer risks, depending on the type of cancer.
- Specific trends noticed in the research include a reduced intake of meat correlating with a decreased risk of colorectal cancer, and observed protection against breast cancer in postmenopausal women following a vegetarian or vegan diet.
- However, the diet-related effects on other prevalent cancers like prostate cancer have been less conclusive, and possible confounding factors like body weight, exercise habits, and other lifestyle choices could impact the observed relationships.
- A diet rich in vegetables, fruits, beans, and whole grains, not only excluding meat, is associated with lower cancer risks according to dietetics experts.
- While reducing meat intake can be a healthy choice, substituting it with highly processed alternatives might decrease the nutritional benefits of a plant-based diet.
Research efforts from the United Kingdom do not explicitly confirm that vegetarian and vegan diets definitively decrease the risk of cancer. It was observed that factors such as body weight may play a role in the witnessed benefits.
However, their findings, drawn from a sample of over 470,000 participants, provide a strong indication that diets excluding or limiting meat are likely related to reduced cancer risks.
Meat Consumption and Cancer Risk
The research suggested that the relationship between diet and cancer risk could vary depending on the type of cancer, according to lead researcher, Cody Watling of the University of Oxford.
One key discovery reinforced prior results: a reduced intake of meat correlates with a decreased risk of colorectal cancer.
Individuals adhering to a “low-meat” diet (five or fewer servings of red meat or poultry per week) had a 9% lower risk of colon cancer, in contrast to those who consumed meat with greater frequency. “Previous evidence has already shown a high intake of processed and red meat is linked to a higher risk of colorectal cancer,” stated Watling.
Respected groups such as the World Cancer Research Fund and American Cancer Society recommend moderating the consumption of red and processed meat to reduce the risk of colon cancer.
Study Findings on Other Common Cancers
The diet-related effects on other prevalent cancers like breast and prostate have been less conclusive.
Watling’s research indicated that a vegetarian or vegan diet appeared to protect against breast cancer, specifically in postmenopausal women. They witnessed an 18% lower risk of the disease in comparison to postmenopausal women who consumed meat more than five times per week.
However, upon further examination, this relationship was largely attributed to the lower body weight found in vegetarian women. An elevated postmenopause weight or obesity level significantly increases the risk of breast cancer, as fat tissue produces estrogen, according to the American Cancer Society.
Should vegetarianism lead to a reduction in weight in women, it could potentially decrease the risk of breast cancer. However, Watling highlighted that these women may have lower body weights for reasons unrelated to their diets, such as their exercise regimes.
The Impact of Diet on Prostate Cancer
In the case of prostate cancer, the study discovered a lowered risk among men who adopted vegetarian, vegan, or pescatarian diets (consuming fish but abstaining from meat). Their risk of the disease was 20% to 31% lower in comparison to frequent meat consumers.
Yet, Watling advised caution on this finding, noting that there are no established dietary risk factors for prostate cancer, and various reasons could account for the decreased risk among men on meat-free diets.
One of the challenges in such studies is the isolation of the impact of diet from the multiple interconnected factors such as other lifestyle choices, income, and healthcare access.
Tackling Confounding Factors
Watling and his team attempted to adjust their results for these “confounders.” They made statistical adjustments to consider people’s weight, exercise habits, smoking and alcohol consumption, education level, and the use of certain medications like aspirin and hormone replacement therapy.
However, it’s not feasible for studies to account for all differences between meat lovers and those who refrain from it, noted registered dietitian and Academy of Nutrition and Dietetics spokesperson, Julie Stefanski.
Additionally, adopting a vegetarian or vegan diet does not necessarily translate into a healthier lifestyle, Stefanski argued. If these diets largely rely on highly processed meat alternatives as opposed to whole plant foods, they might be less nutritious than diets that include fish and other animal products.
Importance of Whole Foods and Reduced Meat Intake
According to Stefanski, the expert consensus remains that diets rich in vegetables, fruit, beans, and fiber-rich whole grains are associated with lower cancer risks.
“These foods are abundant in nutrients and phytochemicals that protect against cancer development by promoting DNA repair, eliminating carcinogens, influencing gene expression, and reducing inflammation,” said Stefanski.
As such, the foods incorporated into a diet – not just excluded from it – are critical, Stefanski emphasized.
Stefanski argues that reducing meat in your diet is prudent. “If you enjoy meat,” Stefanski said, “it’s important to opt for smaller portions and less processed options devoid of substances that have been linked to an increased risk of cancer by experts.”
These findings are based on a sample of over 472,000 U.K. adults between the ages of 40 and 70 participating in the U.K. Biobank study. Over an average of 11 years, nearly 55,000 developed cancer. The majority were meat eaters, but about 10,700 followed a pescatarian diet and almost 8,700 adhered to a vegetarian/vegan lifestyle. The extensive scope of the study allowed for an in-depth examination of different diet patterns and specific types of cancer.
For further guidance on healthy eating, consult the advice from the American Cancer Society.