Given the recent publicity surrounding meat consumption, I thought it was time to re-post this one…
Red Meat Consumption and Mortality
An Pan, PhD. et al. Archives of Interal Medicine. Published online March 12, 2012. doi:10.1001/archinternmed.2011.2287
Background: Red meat consumption has been associated with an increased risk of chronic diseases. However, its relationship with mortality remains uncertain.
Methods: Observation of 37,698 men from the Health Professionals Follow-up Study (1986-2008) and 83,644 women from the Nurses’ Health Study (1980-2008) who were free of cardiovascular disease (CVD) and cancer at baseline. Diet was assessed by validated food frequency questionnaires and updated every 4 years.
THE ‘RESULTS’ – as published in the study conclusion notes and in the media release
Red meat consumption is associated with an increased risk of total, CVD, and cancer mortality. Substitution of other healthy protein sources for red meat is associated with a lower mortality risk.
NOW, THE FACTS:
Over the years, I’ve heard almost every reason as to why we shouldn’t eat red meat, from claims of it fermenting in your gut to it being riddled with parasites. Many tend to read such claims in trashy magazines and jump on the ‘meat is evil’ bandwagon. So let’s look at some facts…
As far as the reliability of the study design goes, it’s pretty poor. For science to determine what causes a potential health risk, they generally take two identical groups (rats for example) and subject them to identical conditions, with the exception of one group who gets a drug, food or whatever is being investigated. For example, if one of the two groups of rats was being fed a drug and they all died, yet the other identical group all lived, there’s relatively compelling evidence that the drug killed them.
The Red Meat Consumption study was not this type of study. It was what is known as an ‘observational’ study. There were no identical groups, no diet fed to the participants, no clinical testing. Instead, the participants completed a ‘food frequency questionnaire’ (FFQ) several times over a span of thirty years or so. The first thing they teach you when studying a nutrition degree is that FFQ’s are notoriously unreliable. Can you recall what you ate for lunch last month? If so, could you accurately describe the source or quality of the food or the quantity? Of course not – it’s absurd to assume one could.
There have been many ‘observational’ studies performed over the years which have shown one conclusion, only to be completely debunked years later. One example was Hormone Replacement Therapy (HRT). Early observational studies concluded that taking HRT seemed to show a 44% reduction in heart disease, yet a later randomised control trial revealed that HRT was far from protective, proving to increase heart disease risk by a whopping 29%!
The participants in this recent red meat study completed a questionnaire about their dietary and lifestyle habits and then this data was correlated with statistics on disease prevalence, such as cancer and heart disease, in an effort to see if there may be any association between red meat and disease. Once a correlation can be established, this will usually generate a randomised control trial based on the hypothesis. This ‘study’ didn’t challenge the theory that red meat increases our risk of disease and there have been many studies which have found quite the opposite to be the case. We must remember that correlation is not necessarily cause. We could say that the presence of umbrella’s increases dramatically each time it rains, therefore umbrella’s cause rain!
In this recent Harvard study on red meat, a scale was developed on how much red meat the participants consumed, ranging from practically vegetarian to regular meat eaters. On this scale, as the consumption of meat increases, so too does the rate of dying. However, as the meat consumption increases, so too does the rate of smoking and alcohol consumption, plus this group exercised less.
They also consume less plant foods and fibre, exacerbating slow digestion and allowing nitrates (from processed meats) and carcinogens (charred meat) to sit in the gut for a longer time, promoting higher absorption. To top it off, this group consumed significantly more calories had a higher BMI and blood pressure … all ingredients for increased risk of disease. Interestingly, the higher meat eaters had LOWER cholesterol than the vegetarians!
I am yet to see a single clinical trial which shows that a diet of lean, unprocessed meat eaten in balance with colourful fresh plant foods increases our risk of any disease in humans. Perhaps if you’re living on a diet filled with highly processed meats full of nitrates and altered fats, you could anticipate an increased risk of disease, but clean, lean, grass-fed beef? We have an abundance of high quality produce in Australia. Lean red meat is full of protein, iron and B-vitamins – all essential to a health body, optimum lean muscle tissue and a strong immune system. So what can you take from this? Don’t believe the hype!