High Protein Diets and Cancer Risk
A recent study has had some alarming findings with high protein diets linked to increased cancer risk. The study found that a high protein diet might have a harmful effect on health and found that high protein diets increase cancer risk as much as smoking cigarettes.
High levels of dietary animal protein in people under 65 years of age was linked to a fourfold increase in their risk of death from cancer and twice the risk of diabetes. Nutrition experts have however cautioned people from changing their diets until further studies have been conducted into the animal-protein cancer link.
Interestingly, the increased cancer risk was did not occur to the same extent when the additional protein came from plant sources instead of animals.
In general the study points to middle aged people who consume a lot of animal protein dying younger from cancer and other diseases. Individuals who consumed a diet high in plant protein had less risk of cancer than those on animal protein. Individuals who consumed a diet which was not high in protein had the least cancer risk.
But the findings became even more complex when it was noticed that the high protein diet in old age had better health. That means this research found that in adults should maintain a low protein diet, which avoided animal protein, until they reached old age and then a diet high in protein would actually be beneficial!
This is because when people reach old age they lose muscle density and can become frail. A high protein diet helps combat that effect and preserve overall health. In people over 65, a high-protein diet cut the risk of death from any cause by 28%, and additionally reduced cancer deaths by 60%.
The research came from a pool of 6,381 people aged 50 and over who were a part of the National Health and Nutrition Examination Survey (NHANES) in the United States.
This study may have some ramifications on the recently popular Atkins and Paleo diets which are very high in protein. According to researchers, individuals should restrict themselves to no more than 0.8g of protein per kg of body weight per day. So the average 80kg male should be consuming no more 64 grams of protein per day.
Most of protein should also come from plant sources, so legumes, mushrooms and vegetables. According to the study, consuming large amounts of animal protein can be very dangerous to your health so it is worth examining how much animal protein you are taking in.
On average, survey participants consumed 1,823 calories a day, which included 51% carbohydrates, 33% fat, and 16% from protein. On average, about 10% of their total calorie consumption was animal protein. Researchers suggested that people who consumed “high protein” diets were eating diets with 20% or more protein. Midrange was considered 10-19% and low was below 10%.
There are possible problems with this study which might throw off the results. For example do lifestyle factors of various demographics play a role? Vegetarians would have diets low in animal protein but they may also be more inclined to be more health conscious and exercise more often than someone who has a diet high in animal protein including hamburgers and hotdogs. In this case the vegetarian is more likely to be physically fit, not overweight and therefore less likely to have certain types of cancer (colorectal). Lifestyle factors like that could throw the results of the study off slightly.
For that reason nutritional experts like Peter Emery, head of nutrition and dietetics at King’s College London says: “I would urge general caution over observational studies, and particularly when looking at diet, given the difficulties of disentangling one nutrient or dietary component from another. You can get an association that might have some causal linkage or might not”
In a follow up study into the role that protein plays in the formation of cancer, researchers found that levels of a growth hormone called IGF-1 rose and fell in line with protein intake. The increase in this growth hormone might in fact be linked with cancer risk. Tests in mice have also shown that high protein diets leads to increased cancer risk and large tumors.