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Does too much protein in the diet increase cancer risk? - Printable Version

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Does too much protein in the diet increase cancer risk? - James - 07-01-2012 12:19 AM

Does too much protein in the diet increase cancer risk?

A great deal of research connects nutrition with cancer risk. Overweight people are at higher risk of developing post-menopausal breast cancer, endometrial cancer, colon cancer, kidney cancer and a certain type of esophageal cancer. Now preliminary findings from researchers at Washington University School of Medicine in St. Louis suggest that eating less protein may help protect against certain cancers that are not directly associated with obesity.

The research, published in the December issue of the American Journal of Clinical Nutrition, 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 the study's first author Luigi Fontana, M.D., Ph.D., assistant professor of medicine at Washington University and an investigator at the Istituto Superiore di Sanità in Rome, Italy. "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."

The study involved three groups of people. The first ate a low-protein, low-calorie, raw food vegetarian diet and was made up of 21 lean men and women. Another group consisted of 21 lean subjects who did regular endurance running, averaging about 48 miles per week. The runners ate a standard Western diet, consuming more calories and protein than group one. The third group included 21 sedentary people who also consumed a standard Western diet, higher in sugars, processed refined grains and animal products. The subjects were matched for age, sex and other demographic factors, and no one smoked or had diabetes, cardiovascular disease, cancer, lung disease or other chronic illness.

Protein intake was, not surprisingly, lowest in the low-protein group. They averaged a daily intake of 0.73 grams of protein per kilogram of body weight. Endurance runners ate 1.6 grams and sedentary people on the Western diet, 1.23 grams. The recommended daily allowance for protein intake is 0.8 grams. That's about three ounces of protein per day for a 220-pound man.

"It's interesting to us that both the runners and especially the sedentary people consumed about 50 percent more protein than recommended," says Fontana. "We know that if we consume 50 percent more calories than recommended, we will become obese. But there is not a lot of research on whether chronic over-consumption of protein also has harmful effects."

Fontana and colleagues found significantly lower blood levels of plasma insulin-like growth factor 1 (IGF-1) in the low-protein diet group than in either the equally lean runners or the sedentary people eating a standard Western diet. Past research has linked pre-menopausal breast cancer, prostate cancer and certain types of colon cancer to high levels of IGF-1, a powerful growth factor that promotes cell proliferation. Data from animal studies also suggest that lower IGF-1 levels are associated with maximal lifespan.

"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."

He calls the study a hypothesis-generating paper that suggests connections between dietary protein and epidemiological studies that show associations between IGF-1 levels and the risk of cancer. But he says more research is needed to clarify what that connection is.

The researchers also found that the group of endurance runners in the study consumed the highest number of calories, averaging more than 2,600 per day. Those on a standard Western diet consumed just over 2,300 calories daily, while those in the low-calorie, low-protein group ate just under 2,000 calories a day. Members of the latter group also tended to weigh less than sedentary people but slightly more than the endurance runners. The average body mass index (BMI) in the low-protein, low-calorie group was 21.3. BMI averaged 21.1 among the runners and 26.5 among those who were sedentary. BMI is a measurement of weight divided by height squared. People with a BMI greater than 25 are considered overweight.

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 a level closer to the range recommended by the nutrition experts of the Food Nutrition Board of the National Academy of Sciences. It also might result in lower levels of IGF-1.

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

RE: Does too much protein in the diet increase cancer risk? - James - 07-01-2012 01:00 AM

How do you explain the Eskimos? They eat nothing but fat, very little vegetable matter, and perhaps a berry or two. No cancer, no diabetes, no heart disease, no gum disease. There are also indigenous people that subsided on fish and coconuts, also without any vegetables. That was it! They didn't start getting sick until carbs were introduced to their diets.

First of all fats are not proteins. What raises the IGF-1 is high protein. And again even at that there are other factors in play. Just like we know estrogens can cause cancer, but not everyone exposed to estrogen is going to get cancer.

And Eskimos do get cancer:

And heart disease:

And diabetes:

And gum disease:

Granted that changes in diet may have contributed to the rise in some of these conditions. On the other hand where are the studies showing lower rates of these diseases prior to changes in their native diet to a more Westernized diet?

I am sorry if I sound over skeptical, but all the claims sound like some multi level marketing sales pitch where they are claiming this is answer to make you live to be over 100 years old based on people in one part of the world doing.......... You care to take a guess as to how many times I have heard these claims? And it is always the same style of they have no disease, but no validating proof. And thus the problem I have. There are a lot of assumptions in the claim that high protein is safe or healthy. Proof of the claim is lacking though.

In addition there are a few other important facts that are being overlooked.

For one the Eskimos do get cancer, but the rates for certain cancers are different than other parts of the world. Does this really have to do with diet? Or could it have something to do with they are not being exposed to the high levels of PCBs, DDT, dioxins, metals, etc. that people in other parts of the world are exposed to?

Then these is the fact that they consume omega 3 fatty acids than the average American. Again the topic is high protein, not fats. But when Americans think protein beef is usually the first thing that comes to mind. Keep in mind though that beef is loaded with omega 6 fatty acids including the pro-inflammatory arachidonic acid (AA). Again inflammation, including that from AA can promote cancer. So to compare the high protein American diet loaded with omega 6s to the Eskimo diet loaded with anti-inflammatory omega 3s is comparing apples to oranges.

And finally there is the fact that the Eskimo's diet is based on thousands of years of adaptation. So again, this does not mean Americans can just suddenly go on an Eskimo diet and expect to be healthy. Even a person who has been a strict vegetarian for years cannot suddenly go on a high protein meat diet without getting sick. The body adapts to diets to a large extent. Although this still does not mean that the body will be healthy if it adapts to a strict diet.

You may also want to look at this on the Inuit diet, which shows where their C came from and the fact that they do consume plant matter, not all fat and meat:

Main article: Inuit diet

The Inuit have traditionally been hunters and fishers. They still hunt whales, walrus, caribou, seal, polar bears, muskoxen, birds, and at times other less commonly eaten animals such as the Arctic Fox. The typical Inuit diet is high in protein and very high in fat - in their traditional diets, Inuit consumed an average of 75% of their daily energy intake from fat.[25] While it is not possible to cultivate plants for food in the Arctic the Inuit have traditionally gathered those that are naturally available. Grasses, tubers, roots, stems, berries, and seaweed (kuanniq or edible seaweed) were collected and preserved depending on the season and the location.[26][27][28][29][30] There are a vast aray of differenthunting technologies that the Inuit used to gather their food

In the 1920s anthropologist Vilhjalmur Stefansson lived with and studied a group of Inuit.[31] The study focused on the fact that the Inuit's extremely low-carbohydrate diet had no adverse effects on their health, nor indeed, Stefansson's own health. Stefansson (1946) also observed that the Inuit were able to get the necessary vitamins they needed from their traditional winter diet, which did not contain any plant matter. In particular, he found that adequate vitamin C could be obtained from items in their traditional diet of raw meat such as Ringed Seal liver and whale skin (muktuk). While there was considerable scepticism when he reported these findings, they have been borne out in recent studies.[32]

RE: Does too much protein in the diet increase cancer risk? - James - 07-01-2012 01:02 AM

Something interesting to note, indigenous Australians also had a very high protein diet, consisting mainly of meat, with some yams, seeds and fruits. One of the ways in which they obtained adequate vitamin C, was from eating the intestinal contents of grass eating animals, such as kangaroos. Not all tribal groups did this, but many desert people did, because the vegetable content of their diet was so low.

They probably learned this form observing wild animals, which often do this. For example wild wolves will go after the guts of the animal they killed first for the plant material being digested in their systems. Then they go after the muscle tissue.

RE: Does too much protein in the diet increase cancer risk? - henrywronger - 08-27-2012 11:36 AM

There are easy and normal elements that can be accomplished to increase breast health and reduce risk of breast cancer as well as reduce risk of duplicate. Breast cancer protection begins with sensible behavior and unique factors that you can manage.