March 16, 2012

The math behind the red meat study

BBC - Over the study period, an extra portion of unprocessed red meat was associated with an overall 13% increased risk of death annually (and the figure for processed meat was even higher).

But what does this mean?

The easiest way to understand it is to think of how this might affect two friends who live very similar lives, according to David Spiegelhalter, a Cambridge University biostatistician, and the Winton Professor of the Public Understanding of Risk.

Imagine that the two friends are men aged 40, who are the same weight, do the same amount of exercise and do the same job.

The only difference between them is that one eats an extra portion of red meat every day - an extra 85g, or 3oz.

"Let's say that every work lunchtime one of them had a hamburger and the other didn't.

"What the study found is that the one who likes the meat had a 13% extra risk of dying. They're both going to die in the end, but one has got this extra annual risk of dying."

But what does that extra risk amount to in practice - for these two average people? The paper doesn't say.

Spiegelhalter has been working it out.

"The person who eats more meat is expected to live one year less than the person who doesn't eat so much meat. You'd expect the 40-year-old who does eat the extra meat to live, on average, another 39 years, up to age 79, and the person who doesn't eat so much meat, you'd expect him to live until age 80."

But Spiegelhalter says there is another way to look at the statistics, which might make the issue seem more urgent. That one year off the life of this 40-year-old hypothetical burger eater is equivalent to losing half an hour a day.

"On average, when he's sitting eating his extra burger, that person is losing half an hour of life because of that meal. On average, it's equivalent - scaled up over a lifetime - to smoking two cigarettes a day, which is about half an hour off your life.

"Or, it's equivalent to being a bit overweight - about 5kg overweight - which I am, so I'm losing, on average, every day, half an hour off my life expectancy."

But should we really believe the findings of this study? Does eating red meat and processed meat cause cancer and cardiovascular disease and shorten life?

Well, no we can't say there's cause and effect here. All that can be said is that there appears to be a strong correlation between eating this kind of meat and having these health problems.

2 comments:

Anonymous said...

When they do these meat studied do they use feedlot meat or do they use pastured or grass fed meat?

Feed lot beef is made from cattle that are overcrowded and fed grain which isn't normal cattle food, plus antibiotics and hormones to increase size and stressed from being overcrowded. This negatively affects meat quality and nutritional value.

Grass fed beef is leaner and made from cattle that graze on range land and pasture, they get grass the food cattle were designed to eat, excercise, and sunshine, all of which make for a better more nutritious meat. The problems of feedlot meat could be causing meat to look worse than it should be, simply by poor production choices on the part of the producers.

Anonymous said...

Excellent point. Those types of details are rarely given in articles like this.