Protein-Heavy Diets and the Potential Risks to Cancer

Key Takeaways:

• Diets low in protein may reduce the risk of various types of cancers, while diets high in protein can increase this risk due to hormones like insulin-like growth factor 1 (IGF-1).
• A group of lean individuals following a low-protein, low-calorie, plant-based, raw food diet in a study showcased lower blood IGF-1 levels compared to athletic and sedentary people following a standard Western diet.
• Dietary changes towards more whole grains, beans, fruits, and vegetables, and less animal products could reduce total calorie consumption, lower protein intake, and possibly result in decreased IGF-1 levels, promoting a healthier lifestyle.
• Research indicates that the average protein intake in countries like the United States and Italy is 50% more than the recommended amount, which could potentially increase cancer risk and accelerate aging.
• While these findings suggest a link between a high-protein diet and cancer, both leading researchers stress the need for further studies before recommending wide-scale dietary changes.

An investigation into diet and cancer risk suggests that diets low on protein might aid in safeguarding against various types of cancers, while diets heavy in protein could heighten the risk.

Link Between Diet and Increased Cancer Risk

The pilot study demonstrated that lean individuals who follow a long-term, low-protein, low-calorie diet, or regular endurance workouts have reduced plasma growth factors levels, and particular hormones including insulin-like growth factor 1 (IGF-1). These substances have been previously associated with an increased risk for multiple types of cancer, like premenopausal breast cancer, certain cases of colon cancer, and prostate cancer.

Dr. Luigi Fontana, an assistant medicine professor at Washington University and the study’s leading author stated, “We are aware of a relationship between nutrition and cancer. There are specific cancers related to levels of IGF-1, an essential growth factor that stimulates cell proliferation.”

In accordance with Fontana, the presence of higher IGF-1 levels amplifies the probability of mutation-affected cells transforming into cancer cells. “In people on a low-calorie, low-protein diet, we observed lower IGF-1 levels compared to lean athletes on a Western diet. This implies that low protein consumption may reduce IGF-1, regardless of body weight,” added Fontana.

Research Findings and Implications

The study, housed in the December issue of the American Journal of Clinical Nutrition, reviewed three distinct groups of people. The first group consisted of 21 lean individuals who followed a low-protein, low-calorie, plant-based, raw food diet. The second group of 21 people were regular endurance runners averaging around 48 miles a week. They followed a standard Western diet which comprised more calories and protein than the first group’s diet. The third group was made up of 21 sedentary participants, also maintaining standard Western dietary habits – high in sugars, heavily processed refined grains, and animal products.

The researchers noted that the group consuming the low protein diet had considerably lower blood IGF-1 levels in contrast with both the athletic and sedentary group. It is already known that high IGF-1 levels pose a risk for premenopausal breast cancer, specific colon cancer types, and prostate cancer.

Diet Change for Healthier Living

Moreover, Fontana hinted at the idea that if individuals adapted their diet to include more whole grains, beans, fruits and vegetables, while minimizing animal products, overall health may improve. The researcher suggested consuming fish, low-fat dairy products, and, occasionally, some red meat. Such dietary changes reduce total calorie consumption, lower protein intake, and possibly result in decreased IGF-1 levels—working towards a healthier lifestyle.

In countries such as the United States and Italy, the protein intake is on an average 50% more than the recommended amount. “Protein overconsumption may enhance cancer risk and potentially accelerate aging, but we need further studies to verify if this hypothesis holds validity,” Fontana speculated.

Concurring Study Outcomes

Additional research studies concur with Fontana’s findings. Dr. Dimitrios Trichopoulos, the Vincent L. Gregory Professor of Cancer Prevention in the Department of Epidemiology at the Harvard School of Public Health, commented: “A research paper we recently published also corroborates that a high-protein diet is less than ideal. It diminishes survival rates; it increases the risk of cancer.”

In the study, featured in the November 29 issue of the European Journal of Clinical Nutrition, researchers gathered dietary data from 22,944 healthy adults. The findings denoted a correlation between diets low in carbohydrates and high in protein with increased mortality.

Although Trichopoulos agrees with Fontana’s findings, he still retains some reservations. He contends that “At this juncture, it would be premature to recommend a low-protein diet on the grounds of cancer risk reduction or elongating life span”. Both Fontana and Trichopoulos highlight the need for additional research and data before recommending dietary changes on a large scale.

Further Information

For additional expertise and knowledge, the American Cancer Society provides in-depth information about diet associated with cancer.