For years, protein shakes have been hailed as a quick, convenient, and effective way to boost muscle growth and aid in weight loss. These drinks, often consumed by fitness enthusiasts and those seeking healthier alternatives to sugary snacks, are widely marketed as beneficial for both physical performance and overall health. However, recent research has raised serious concerns about the long-term health consequences of consuming protein shakes, especially when consumed regularly. Dr. James Kinross, a leading colorectal surgeon from Imperial College London, has issued a stark warning that protein shakes could increase the risk of colon cancer-a disease that has been rising alarmingly among young people in recent years.

In this article, we explore the warning signs, scientific evidence, and expert opinions surrounding the potential risks of consuming protein shakes, and why they may not be the health food they are made out to be. From the increase in bowel cancer diagnoses to the effects of processed ingredients and toxins in protein powders, we break down the impact of this widely consumed supplement.

Doctors are sounding the alarm over the dangerous 'obsession' with having lots of protein and the modern approach to supplementation

The Rise of Bowel Cancer Among Young People

Over the last 30 years, colon cancer rates among young adults have skyrocketed by 80% globally. Once considered a disease that predominantly affects older individuals, colon cancer is now increasingly being diagnosed in people in their 20s, 30s, and 40s. In fact, recent studies have shown that the rates of colon cancer have surged by nearly 15% in the last decade alone, a troubling trend that has baffled doctors and health experts worldwide.

In the UK alone, over 32,000 cases of colon cancer are diagnosed every year, while the US sees a staggering 142,000 diagnoses annually. What is causing this dramatic increase, particularly among younger individuals? Many experts believe that a combination of factors-including rising pollution, sedentary lifestyles, increasing obesity rates, and changes in diet-may be contributing to this unsettling trend. Among the various dietary factors being studied, the rise in consumption of ultra-processed foods, including protein powders and shakes, is increasingly being linked to an increased risk of colon cancer.

The Role of Protein Shakes in the Development of Colon Cancer

While protein shakes are often marketed as a healthy and essential part of an active lifestyle, research conducted by Dr. James Kinross has raised alarms about the potential risks they pose to gut health and overall wellness. Dr. Kinross, who has over two decades of experience treating cancer patients, points to the harmful effects of protein powders, particularly those that are heavily processed. According to Dr. Kinross, these protein powders "profoundly change the gut microbiome," which is the community of beneficial bacteria that help maintain digestive health.

"These protein powders are bad news and really bad for your gut," says Dr. Kinross. "When your body breaks down and metabolizes proteins, one of the by-products is toxins that drive inflammation and contribute to the development of bowel cancer."

Bowel cancer can cause you to have blood in your poo, a change in bowel habit, a lump inside your bowel which can cause an obstructions. Some people also suffer with weight loss a s a result of these symptoms

The gut microbiome plays a crucial role in the body’s immune response, digestion, and overall health. A healthy gut microbiome helps protect the body from harmful bacteria and supports proper nutrient absorption. However, consuming protein powders, which often contain artificial additives and highly processed ingredients, can disrupt this delicate balance. The inflammation caused by these changes can damage the cells in the gut, potentially leading to the development of cancerous cells.

The Impact of Ultra-Processed Foods on Gut Health

The growing body of research linking ultra-processed foods to increased cancer risk has raised concerns about the broader implications of consuming protein powders and other processed food products. Studies have consistently shown that diets high in ultraprocessed foods can disrupt the balance of bacteria in the gut, triggering inflammation that can lead to a host of health complications, including bowel cancer.

In particular, certain additives found in protein powders-such as emulsifiers and preservatives-have been shown to have a detrimental impact on gut health. These chemicals can alter the composition of the microbiome, leading to reduced bacterial diversity and increased intestinal inflammation. Research published in the Journal of Nutrients in 2024 revealed that emulsifiers commonly found in protein shakes, such as carrageenan, can break down in the stomach and turn into a toxic substance. This toxic substance can trigger intestinal ulceration, further disrupting the gut microbiome and increasing the risk of cancer.

Dr. Maria Abreu, president of the American Gastroenterological Association, has also highlighted the role of chronic inflammation in the development of colon cancer, saying, "Chronic inflammation leads to colon cancer, and I suspect that's transformative in this new rise of young people developing colon cancer." Dr. Abreu believes that the addition of emulsifiers to the food supply has significantly contributed to the rise in colon cancer cases, particularly among younger individuals.

The Dangers of Consuming Processed Red Meat and Protein Powders

In addition to protein shakes, Dr. Kinross warns against the consumption of processed red meats, such as bacon, sausages, and deli meats. These foods are also linked to an increased risk of colon cancer, with research identifying several harmful chemicals present in processed meats, including nitrates, heme iron, and amines. "If you're going to have red meat, you want to have high-quality red meat," Dr. Kinross advises. "And it should be a once-a-week thing. It's a treat."

US specialists have said frequently consuming a high 'inflammatory diet' is being 'overlooked'. Foods that fall under the category include red and processed meats, sugary drinks, refined grains like white pasta or bread and even tomatoes


The Nova system, developed by scientists in Brazil more than a decade ago, splits food into four groups based on the amount of processing it has gone through. Unprocessed foods include fruit, vegetables, nuts, eggs and meat. Processed culinary ingredients — which are usually not eaten alone — include oils, butter, sugar and salt

Nitrates, while not carcinogenic on their own, can interact with digestive chemicals in the body to form cancer-causing compounds. These compounds can damage the cells in the colon, leading to the development of cancerous growths. Dr. Kinross recommends replacing processed meats with healthier alternatives, such as white fish or chicken, to reduce the risk of bowel cancer.

The key takeaway from Dr. Kinross's advice is the importance of moderation and choosing high-quality, minimally processed foods. "You don't need to be vegan to have a healthy gut. That's definitely not true," he adds. "But what you shouldn't be doing is having meat with every single meal." By balancing your diet and avoiding excessive consumption of processed foods, you can significantly reduce your risk of developing colon cancer and other serious health conditions.

The Impact of Ultra-Processed Foods on Mortality Rates

The risks of ultra-processed foods go beyond cancer, with recent studies linking them to an increased risk of premature death. Research conducted in Brazil found that ready-to-drink protein shakes are as harmful as some of the most unhealthy snack foods, like Kinder Joy chocolate eggs. Both protein shakes and chocolate eggs have similar calorie counts and are classified as ultra-processed foods, which are associated with a range of non-communicable diseases, including heart disease, diabetes, and cancer.

A study published in the American Journal of Preventive Medicine found that for every 10% increase in calories from ultra-processed foods, the risk of dying early from any cause increased by 2.7%. These findings suggest that consuming protein shakes and other ultra-processed foods on a regular basis could significantly raise your risk of premature death. In fact, research from the CDC indicates that ultra-processed foods account for more than half of the average daily calorie intake in the United States, contributing to approximately 13.7% of all premature deaths each year.

Conclusion: Rethinking Your Protein Supplement

While protein shakes have become a staple for many individuals looking to maintain muscle mass or lose weight, recent research suggests that these seemingly innocent supplements may pose significant risks to long-term health. From their potential to disrupt gut health and increase inflammation to their link with the rising incidence of bowel cancer, protein powders may not be as healthy as they are made out to be.

Experts like Dr. Kinross emphasize the importance of avoiding ultraprocessed foods, including protein powders, in favor of plant-based proteins such as pulses, legumes, and whole grains. By making smarter dietary choices and limiting your intake of processed foods, you can help protect your gut health and reduce your risk of developing colon cancer and other serious health conditions.

As the evidence continues to grow, it’s clear that moderation is key. If you're considering incorporating protein supplements into your diet, it’s crucial to weigh the potential risks against the benefits. Opting for whole, unprocessed foods and a balanced diet will not only support muscle growth but also help ensure a healthier gut and overall well-being. By being mindful of what you consume, you can make choices that promote long-term health and reduce the risk of developing life-threatening diseases like colon cancer.