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Will eating meat cause mid-life cancer?

Meat (protein)Do you remember about a month ago, there was a day or two where a study highlighting that middle-aged people who ate protein were at an increased risk for cancer?This of course, probably shot yet another arrow across the already quivering Atkins and Paleo diet eaters as their lifestyle is based on high protein/low carbohydrates.

I admit I dismissed this study pretty much along with all other studies that indicate eating something that is part of the five food groups is bad for you. Until I recently read an article about study behind the headlines which made me seriously question it!

The research behind this was published in the journal, Cell Metabolism (March 2014) (full reference below) and spearheaded by Morgan Levine from the University of Southern California in Los Angeles. To quote from the introduction,

The study population included 6,381 adults ages 50 and over from NHANES III, a nationally representative, cross-sectional study. Our analytic sample had a mean age of 65 years and is representative of the United States population in ethnicity, education, and health characteristics. On average, subjects consumed 1,823 calories, of which the majority came from carbohydrates (51%), followed by fat (33%) and protein (16%), with most of it (11%) derived from animal protein. The percent of calorie intake from protein was used to categorize subjects into a high protein group (20% or more of calories from proteins), a moderate protein group (10%–19% of calories from proteins), and a low protein group (less than 10% of calories from proteins).

So far so good. What follows is a big long detailed discussion of the diets, linking the eating styles of the individuals with potential for diseases, and then testing said theories against mice (who have a shorter lifespan so slightly easier to test). And as a result of all this analysis, the researchers concluded that those who received  20% of their calories from protein, were more likely to die over the next 18 years than their peers where protein accounted for less than 10% of calories in their diet.

And then… buried deep in the discussion is one sentence which should immediately set the alarm bells ringing for anyone about to change their protein intake:

There are some limitations to our study, which should be acknowledged. First, the use of a single 24 hr dietary recall followed by up to 18 years of mortality assessment has the potential of misclassifying dietary practice if the 24 hr period was not representative of a participant’s normal day. However, 93% of our sample reported that the 24 hr period represented a normal day…”

Well, I don’t know about you, but the fact they referred to an important sounding database (NHANES III) above had me convinced there was some long term study on these people’s eating habits – not what did they eat in the last 24 hours???!!!! Think back over what you ate in the last week – would you have had the same mix of carbs, fruit, vege and meat throughout the week??? Apparently other researchers also felt cautious about relying too heavily on these results as evidence by this short article in the magazine, New Scientist.

And if all the above wasn’t confusing enough, at the every end of the article, the author’s, after advising those between 50 and 65 to eat less protein, they recommend people over the ages of 65-70 may want to consider increasing their protein (based on studies done by other people – Bartali et al., 2006, Ferrucci et al., 2003, Kobayashi et al., 2013) – what a headspin…!

Now, I’m not advocating you can dash out and eat cheeseburgers and steaks to your hearts content… With so many conflicting studies about what I should and shouldn’t be eating out there (potato’s – are they in or out today?!), I have come to the conclusion the best way to eat is to follow these simple guidelines (and educating yourself always helps):

  1. Eat everything in moderation (Sage advice from the family doctor of my parent’s generation…And let’s face it – all the researchers in the base article are also saying!)
  2. If it contains chemicals, be cautious – that includes the chemicals that you can’t pronounce, the ones you can, and the ones that have their origins in other food products (corn fructose anyone?)
  3. Keep active and exercise regularly
  4. Remember, you can be a living example of a medically perfect healthy lifestyle, and you can still die from accident, genetics or infections disease (see point one)!

Enjoy life!

(And a special thank you for Cell Metabolism for having the article by Levine et. al. publicly available :-))

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References:

Levine, M.E., Suarez, J.A., Brandhorst, S., Balasubramanian, P., Cheng, C-W., Madia, F., Fontant, L., Mirisola, M.G.,  Guevara-Aguirre, J., Wan, J., Passarino, G., Kennedy, B.K., Wei, M., Cohen, P., Crimmins, E.M., and Longo, V.D., Low Protein Intake Is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population, Cell Metabolism, Volume 19, Issue 3, p407–417, 4 March 2014

Bartali et al., 2006Bartali, B., Frongillo, E.A., Bandinelli, S., Lauretani, F., Semba, R.D., Fried, L.P., and Ferrucci, L. Low nutrient intake is an essential component of frailty in older persons. J. Gerontol. A Biol. Sci. Med. Sci.. 2006; 61: 589–593

Ferrucci et al., 2003Ferrucci, L., Guralnik, J.M., Cavazzini, C., Bandinelli, S., Lauretani, F., Bartali, B., Repetto, L., and Longo, D.L. The frailty syndrome: a critical issue in geriatric oncology. Crit. Rev. Oncol. Hematol.. 2003; 46: 127–137

Kobayashi et al., 2013Kobayashi, S., Asakura, K., Suga, H., and Sasaki, S., Three-generation Study of Women on Diets and Health Study Group. High protein intake is associated with low prevalence of frailty among old Japanese women: a multicenter cross-sectional study. Nutr. J.. 2013; 12: 164

 

 

 

 

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One comment

  1. That study is just another epidemiological study with most people on standard diet and huge number of variables and their combinations where correlations are easily mistaken for causations. How many of those people were actually on paleo diet? Most of those on 20% protein intake still got over 50% carbs and lots of fat. That is supposed to be a high protein paleo diet? That is still a high carb diet and the combination of high carbs and fat is by paleo standards one of the worst thing. The conclusions of the study are ridiculous.