Too much protein increases cancer risk

Earlier this week scientists reported a strong correlation between obesity and the risk of common cancers, such as cancer of the colon and breast cancer. Today, initial findings from a US study suggest that eating less protein could be a way to protect some people from cancers that are not directly associated with obesity.

The research is published in the December issue of the American Journal of Clinical Nutrition (2006, 84, 1456), shows that lean people on a long-term, low-protein, low-calorie diet or participating in regular endurance exercise training have lower levels of plasma growth factors and certain hormones linked to cancer risk. “However, people on a low-protein, low-calorie diet had considerably lower levels of a particular plasma growth factor called IGF-1 than equally lean endurance runners,” says Luigi Fontana of Washington University, “That suggests to us that a diet lower in protein may have a greater protective effect against cancer than endurance exercise, independently of body fat mass.”

“Our findings show that in normal weight people IGF-1 levels are related to protein intake, independent of body weight and fat mass,” Fontana says. “I believe our findings suggest that protein intake may be very important in regulating cancer risk.”

Fontana says most of us don’t eat nearly enough fruits and vegetables or enough whole-grains, cereals or beans. “Many people are eating too many animal products — such as meat, cheese, eggs and butter — as well as refined grains and free sugars,” he says. “Our intake of vegetables and fruits is low, and beans are vastly underconsumed in the U.S. and Europe these days.”

He believes diets would be healthier if we ate more whole grains, beans, fruits and vegetables and far fewer animal products. He recommends mostly fish, low-fat dairy products and, occasionally, some red meat. Such a diet would both cut total calories and reduce the amount of protein we consume to healthier levels.

“Eating too many calories increases our risk of developing obesity, diabetes, cardiovascular disease and of certain types of cancer related to obesity,” Fontana adds, “We hope to further clarify what happens to cancer risk when we are chronically eating more protein than we need.”

14 thoughts on “Too much protein increases cancer risk”

  1. I am 45 years of age and have did body build in the pass, about 6 yesrs and would like to containue building my body , my question is how much protein will i need to containue build muscle i am 5’8″ and at 200 pounds and i would like to lose my body fat with out sacerficing my muscle mass.

  2. Since red meat increases the risk of several cancer sites (colorectal, lung, breast, possibly prostate), this effect has been attributed in the past to the high amount of saturated fat. Nevertheless, according to Prof. Walter Willett, fat is probably not related with the etiology of these cancers. More recently the presence of mutagens in red meat has been strongly associated with carcinogenesis of large bowel and lung. These findings resulted in a paucity of epidemiologic studies on protein and cancer etiology. In short, studies on protein and cancer risk are needed. Our group is conducting a multisite study on this topic and the preliminary results suggest an increase in risk of lung cancer and, possibly, of large bowel.

  3. Excuse me? At what point did I offer any recommendations to anyone? Just because you use the name “Dietitian” in your comment doesn’t prove you’re an expert. I also have no “past beliefs” to let go of. More to the point, my original blog post was reporting on research that essentially confirms what you’re saying in your comment. So, aside from you being impertinent and making personal attacks I’m not actually sure from whence the disagreement you’re claiming we’ve had arises…

  4. Protein is necessary for the building and repair of body tissues.

    (0.8 – 1 g) g per kg of body weight is based on the protein absorbed and utilized for cell growth and all other functions in the body requiring amino acids.
    It regulates body processes, such as water balancing, transporting nutrients, and making muscles contract.
    It produces enzymes, hormones, and other substances the body uses.
    Protein is found in muscles, bone, hemoglobin, myoglobin, hormones, antibodies, and enzymes, and makes up about 45% of the human body. Muscle is approximately 70% water and only about 20% protein.
    Therefore, increasing muscle mass requires extra water, extra energy in the form of carbohydrates (to maintain the needs of that extra muscle), and a little extra protein.
    About 2 oz extra per day.

    Too much protein not only increases your cancer risk but it also can contribute to Chronic Kidney Disease, even if you blood pressure is only mildly elevated.
    Animal protein provides more nitrogenous waist, therefore more urea. Bad for the Kidneys.

    Again: Read The China Study by T. Colon Campbell, University of Cornell Nutrition Department.

    Your lack of nutrition knowledge and evidenced based nutritional medicine can be dangerous when you are making recommendations to others.

    No-one lakes admitting that maybe some of our favorite foods might not be good for us. Food is a VERY personal thing. I understand.
    Let go of past beliefs and read-up.

  5. Think about it. Proteins are the building blocks. We need protein for cell reproduction. We only need 0.8 g protein per kg of body wt. Most American diets are much greater than that. Logically it makes sense that too much protein consumption will increase cell proliferation…hence cancer.
    When we need a certain amount of a nutrient, more is not better. There are always repercussions for over and under intake of needed nutrients.

  6. I don’t think it’s sensible to make assertions either way. It will be interesting to monitor the cancer rates among people who fill themselves up on protein powder drinks though, won’t it? As if anything we eat is truly natural…

  7. Seems to me there is a new “breakthrough” cancer study made each day. Protein is a staple part of our natural diet, and even more important for gym goers and bodybuilders. I can’t imagine that eating lots of protein from natural, healthy sources can increase the chances of cancer

  8. It’s a fact that human breast milk is considerably lower in protein by say, a factor of almost three than cow’s milk which is considerably lower than rat’s milk by say a factor of about ten. Pythagorus would not eat beans but was it their high protein content or just the way he felt after eating a lot of plant protein. nor would Newton or Einstein, presumably because they had read of Pythagorus’ aversion to beans. Human breast milk contains less than one per cent protein, the Meditterranian diet has 20-30% protein at it’s core. Other than the fact that we like to hunt, our stupidity makes us most adorable at supplying extinction to those we don’t like the taste of…. we’re eating a rat’s diet – everything and anything, while our genetic makeup says otherwise.

  9. I agree with Andrew, Too many variables to conisider what “too” much really is. Too much of anything is bad for you in general. Mice arent people, but give a rather simple perspective on theory.

  10. People just don’t eat any xxx after the news ‘Too much xxx increase the risk of …’ because they don’t know how much is ‘too much’ and don’t want any ‘risk’ either. Death rates of mice fail to give any clear answer.

  11. You’re right…I posted this because it just seem to be yet another piece of research like the sugar findings that blurs the rights and wrongs of diet and nutrition again and again.

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