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Over the last week, the mainstream media in many parts of the world has been awash with headlines along the lines of “Eating protein may be as bad as smoking”. Even the nutritionally uninformed know that protein is essential to human life and that smoking is the number one cause of preventable death. We thought this deserved a deeper look!
Protein: The new killer?
Many will have seen the headlines accompanying the recent publication of a study of the health consequences of high intakes of animal protein. “Diets high in meat, eggs and dairy could be as harmful to health as smoking,” fretted the UK Guardian. “Meat and cheese may be as bad as smoking,” wailed Science Daily, while Food Navigator went for the only slightly more sober “Meat and dairy-rich diets may quadruple cancer death risk”.
Unfortunately, we live in an age where most newspaper science and nutrition journalists are incapable or unwilling of going beyond the press releases and examining what the science actually says. As a result, the road to a sensible diet and good health is festooned with conflicting signposts, some of which – on saturated fat, for example – change direction almost weekly. So should we be dropping our eggs and meat into the same rubbish bin as our cigarettes?
The findings, minus the hype
The Cell Metabolism study was authored by a mix of US and Italian authors, the senior author being gerontologist Professor Valter Longo. Prof Longo is well known for his work showing that caloric restriction both increases lifespan and reduces cancer and diabetes risk. His group found that middle-aged people who ate a high-protein diet faced a 74% increase in the relative risk of death from all causes, compared with those of the same age eating a low-protein diet. Worse still, cancer deaths shot up dramatically among those on a high-protein diet, although this effect was only evident when the protein was from animal sources. A separate analysis revealed that “high levels of animal proteins promote mortality and not that plant-based proteins have a protective effect”.
The late-life switcheroo
But interestingly, Longo and colleagues found these results were reversed among the elderly – or those aged 66 years and older. Among this group, those on a high-protein diet experienced a 28% relative risk reduction in all-cause mortality and a 60% relative risk reduction in cancer mortality, compared with those on a low-protein diet.
This result parallels findings from a recent Japanese study, in which elderly men – mean age 67.4 years – with the highest animal protein intake exhibited a 39% decreased risk of functional decline, compared with men consuming the least protein. No effect was observed either for plant protein or for women.
Parallel studies in mice
To test their hypothesis that high levels of animal protein increased cancer and all-cause mortality, they performed a series of parallel experiments on mice. In a nutshell, they showed a similar effect and they related it to the protein insulin-like growth factor-1 (IGF-1), which has been central to Longo’s earlier work on caloric restriction. Longo and others have previously shown that low levels of IGF-1 are linked to reduced cancer and diabetes mortality in humans. This new study now provides supporting evidence for this same effect in a mouse model.
Less than meats the eye
If you’re in middle age, or have yet to hit the grand young age of 66, consider these findings carefully in light of all the available evidence before you decide to cut animal protein from your diet. Firstly, let’s look at some of the limitations of the study:
- The authors used data on 6,381 adult subjects, representative of the US population, taken from the National Health and Nutrition Examination Survey (NHANES) III. As an observational, epidemiological study, NHANES III cannot demonstrate cause and effect – only correlations
- NHANES III data were gathered using a single, 24-hour dietary recall questionnaire performed between 1988 and 1994 – relying on individuals’ often faulty recall of what they ate. Also, the data cannot account for changes that may have occurred in the subjects’ dietary patterns or food composition in the intervening two decades
- Adding weight to the ‘faulty dietary recall’ factor is the reported caloric intake of the NHANES III subjects: an average of 1,823 calories. This sounds surprisingly low for subjects eating the Standard American Diet, and indicates that subjects may have told the NHANES III investigators what they thought they wanted to hear
- The meat and dairy consumed by the NHANES III subjects would overwhelmingly have been derived from large-scale farming operations, including grain-fed animals raised in concentrated animal feeding operations (CAFOs), injected with antibiotics and growth hormones and fed genetically modified (GM) feed. Particularly in the context of an epidemiological study, to blame animal protein per se for the observed mortality associations is scientifically unsupportable with all of these other factors in play
- A large amount of the meat consumed will have been subjected to high-temperature cooking methods, yielding heterocyclic amines and polycyclic aromatic hydrocarbons among other hazardous substances
- Dr Longo is the founder of L-Nutra, Inc. The company’s first product, ProLonTM, is “an all-natural plant-based 5 five-day Fasting Mimicking & Enhancing™ Diet (FMED) program”. Could Dr Longo have an interest in casting animal protein in a bad light? This potential conflict of interest is mentioned in the Acknowledgments at the end of the paper as “V.D.L. has equity interest in L-Nutra, a company that develops medical food”
- Zoe Harcombe discusses the problems of the authors’ use of relative, rather than absolute, risk, and points out that what we’re really looking at is “a base of six deaths, 7.84 deaths per 1,000 person years vs 2.18 deaths per 1,000 person years”
- The high-protein mice in the supplementary study were fed something called ‘AIN-93G standard chow’. This consists of a long list of processed ingredients – including casein and wheat starch – artificial vitamins and calculated levels of amino acids and minerals. Such a diet may be cancer promoting in itself
- This is a direct quote from the paper: “High and moderate protein consumption were...not associated with all-cause, CVD [cardiovascular disease], or cancer mortality when subjects at all the ages above 50 were considered.” Need we say more?
Bearing all this in mind, we think it’s safe to say that this study is being given undue prominence in the media. At best, it appears the authors have applied the statistical thumbscrews until they got an ‘interesting’ result.
Paleo pushback
So why is this study getting so much media attention? It could, of course, be partly explained by journalistic incompetence in matters scientific. But if we look at the articles uncritically promoting the protein/smoking link, another thread emerges: that the increasingly popular paleo diet may be intrinsically unhealthy. Much better, suggests Longo, to eat a “low-protein, plant-based diet” – which is, to steal a paleo meme, “The way our grandparents used to eat”.
Thought management by media
But paleo isn’t a high-protein diet – it’s a moderate-protein one. It also recommends increasing fat intake, cutting back or eliminating sugar, grains, refined carbohydrates and processed foods and increasing carb intake from non-starchy vegetables. Look how far this diverges from official, Big Food-driven dietary recommendations, and consider that mainstream media rely to a huge degree on advertising revenue from the very same Big Food. When studies like Prof Longo’s come along, it’s easy to promote a message designed to scare people off diets like paleo – despite its documented health benefits – and back into the welcoming arms of government-approved eating. It’s been happening with the hoary old saturated fat/cholesterol/heart disease myth for years, and only now is the tide beginning to turn. This is clearly a strategy that works!
Call to action
First, please share or forward this article widely – people need to know more than they’re being told by the mainstream media!
Second, below are some key dietary tips for optimal health:
- Don’t snack! It’s best to leave at least 5 hours between meals
- Drink only water between meals
- Consider introducing intermittent fasting into your lifestyle by having longish overnight fasts and perhaps eating two meals daily, not three. Consider a couple of days a week in which you limit caloric intake to 500–600 calories
- Always eat protein at the same meal as carbs, and make sure your first mouthful is protein, not carbs, to help dampen your insulin response
- Go low glycaemic load by removing or minimising starchy carbs
- Use vegetables and fruit as your key sources of carbohydrate, not starchy carbs like pasta, rice and potatoes
- Use lower-heat cooking methods that minimise protein and fat damage, e.g. slow cooking, sautéing, steaming, etc.
- Incorporate adequate healthy fats (e.g. cold pressed, unfiltered virgin olive oil, medium-chain triglycerides (MCTs) from coconut, omega-3s from cold-water fish and even undamaged saturated fats from organically raised meats) in your diet
- ‘Eat a rainbow every day’ to boost your phytonutrient intake. Ensure you are eating members of the main 5 phytonutrient groups based on colour, namely: green, red, orange, blue/purple and white/tan.
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