Is it dangerous to eat meat if you’re between 55 and 65? Will eating lots of meat then suddenly become healthful after you turn 65?
This is the somewhat confusing conclusion that some researchers drew from a new American questionnaire study:
- The Telegraph: High-protein diet “as bad for health as smoking”
- Science Magazine: Low-Protein Diet May Extend Lifespan
- MailOnline: Eating lots of meat and cheese in middle age is “as deadly as SMOKING”
- Scientific American: Diet High in Meat-Proteins Raises Cancer Risk for Middle-Aged People
- Science Daily: Meat and cheese may be as bad for you as smoking
As usual, we have to take sensational headlines with a substantial pinch of salt. This was just a food questionnaire that was sent to some thousand Americans, and the researchers then looked at statistical associations with diseases.
As regular readers know, one can’t prove causation by correlating statistics from questionnaire studies. Only ignorant or sensationalism-driven journalists believe so. Unfortunately these two groups seem to constitute the vast majority of all journalists.
On subsequent examination, it turns out that at least 80% of similar findings in uncertain questionnaires are incorrect – see table 4 in the excellent review Why Most Published Research Findings are False.
So a more scientifically correct headline would be “There is a 20 percent chance that meat quadruples the risk of cancer for people under the age of 65 and reduces the risk for older people.” Not as enticing.
The statistical correlation between meat-eating and disease in people under 65 in the U.S. may just as well be due to the fact that meat consumption there is associated with eating junk food, smoking, lack of exercise, less vegetables and in principal any unhealthful lifestyle you can think of.
What, in all of these unhealthful lifestyles, is the cause of disease ? Statistics cannot prove this.
IGF-1 and cancer
Therefore, there are good reasons to ignore the study. But I guess that there’s still some truth behind it. Scientists report that protein (high-quality animal protein in particular) may raise levels of the hormone IGF-1, which stimulates cell division. High levels of IGF-1 may in the long run increase the risk of cancer.
What they don’t mention is that carbohydrates also increase levels of IGF-1, at least as much. Particularly bad carbohydrates in greater quantities radically raise IGF-1 levels. The only thing you can eat that doesn’t significantly increase levels of IGF-1 is fat.
The logical conclusion is that any variation of a low-carbohydrate diet with moderate amounts of protein (and enough fat) is the healthiest in the long run – at least to keep IGF-1 low while still feeling great. How much protein? The amount you need to feel good, feel full and stay strong and healthy. What is this concept called? LCHF.
The really ambitious may add intermittent fasting for maximum effect.