Do Avatar characters eat cheese? James Cameron’s films may suspend disbelief, but his dairy claims are fiction, not fact.

In our brave new world, where questioning authority and searching for truth are championed as positive attributes, it is ironic that we tend to follow predictable behaviour patterns when faced with new information. Decisions which we consider to be impartial, or opinions that we hold about controversial issues based on evidence, balance and facts, may prove to be anything but when scrutinised further.

Take, for example, the preponderance of media articles suggesting that meat and dairy consumption are unhealthy – for us, the animals and the planet. One of the most recent, a plea from film-maker and deep-sea explorer James Cameron, plays upon three phenomena relating to decision-making – cultural cognition, bad news bias and confirmation bias.

Figure 8

We assume that we make impartial, balanced decisions, but we’re far more subject to bias than we may think. Graphic from Capper (2017) Cattle Practice.

Celebrities have been used to sell products, messages and ideologies for centuries, from the Royal Family endorsing Wedgewood pottery in the 1760s, to Bette Davis advertising shampoo in the 1950s and Joanna Lumley now gaining publicity for activist causes. However, fame doesn’t imply any degree of expertise, knowledge or understanding of the issue, just a belief that the solution lies with X, whatever X might be.

Most of us aim to be like our heroes, whether they are famous based on appearance, acting ability, athletic skill or career prominence; thus we are prone to cultural cognition. If I believe that celebrity A believes that something is right/wrong and I aspire to being like this celebrity, I am more likely to adopt their message without question. The fact that a famous Hollywood film maker (and deep-sea explorer – seriously, who doesn’t aspire to be a deep-sea explorer?) has sufficient belief to write an op-ed in The Guardian claiming that we should all reduce meat and dairy consumption, therefore resonates with us far more highly than the same message from a non-famous individual.

The inevitable “this is killing us and the planet” rhetoric adds an extra layer of credibility via bad news bias, in that we are preconditioned to believe negative news over positive news. “Bad news sells” is clichéd, yet true (and explains the popularity of “X Causes Cancer” stories in the Daily Mail) and we need five pieces of positive information to negate each piece of negative information.

Confirmation bias is the final layer in this anti-meat and dairy club sandwich. It’s difficult, if not impossible, to have missed media coverage of potential impacts of meat and dairy consumption on health. If we consciously (or subconsciously) absorb the message that these foods are bad, then Cameron’s claims that “eating too much meat and dairy is making us sick, greatly increasing our risk of heart disease, type 2 diabetes, several major cancers (including breast, liver and prostate) and obesity” agree with our existing bias and we are likely to believe them. However, these claims do not accord with (nor are linked to) current scientific literature on dairy consumption.

This would include, for example, a meta-analysis in Breast Cancer Research and Treatment, which demonstrated a negative association between dairy consumption and breast cancer, i.e. increasing dairy product consumption may be associated with a reduced risk of breast cancer. In addition, a dose-response meta-analysis in the European Journal of Epidemiology reported neutral associations (i.e. no clear positive or negative association) between dairy product consumption and cardiovascular and all-cause mortality. Perhaps even the recent article in Nutrition Research Reviews, which concluded that recommending reduced dairy consumption in order to lower saturated fatty acid intakes (and thus the risk of type II diabetes and cardiovascular disease) would have limited, or possibly negative effects.

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Ice-cream (and other dairy products) may reduce the risk of breast cancer.  

When the subject under discussion is the fictional lives of blue-skinned human hybrids (as per the film Avatar, directed by Cameron), it’s perhaps easier to use imagination than rely on scientific veracity. However, having an evidence basis for claims made in media articles is increasingly important, especially when the claims are made by those who are only prominent for their excellence in other (non-scientific) areas.

In the meantime, eat, drink and be merry over the next two weeks – content in the knowledge that clotted cream with your mince pie will not have adverse health effects, and may even prevent against cancer. Merry Christmas and a Happy New Year!

 

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Seeing the Bigger Picture – Why One-Dimensional Panaceas Do Not Solve Sustainability Issues

This week, another paper has been released claiming that we should change to a vegetarian diet in order to “…cut global food emissions by two thirds and save millions of lives“. As ever, media coverage of the paper by Springmann et al. ignored salient points regarding the importance of increasing fruit and vegetable consumption and reducing energy intake in reducing deaths from heart disease, cancer and diabetes; and simply focused on the claim that reducing meat intake would improve health and cut greenhouse gas emissions (GHGs). The simple message to the consumer? Go vegetarian.

So are GHGs the only important environmental metric? Absolutely not. What about land use? Air quality? Fossil fuel consumption? Water use? Biodiversity? The myopic focus on GHGs as the only arbiter of environmental sustainability completely ignores these factors, yet the results of the current study (and similar papers) are promoted worldwide as a panacea to solve all environmental issues.

Can you imagine a world where we only look at one consequence of our actions? Where our only consideration when buying a car is the colour of its paint? Or the criteria for accepting a new job is whether they have good coffee in the canteen? Surely a ridiculous idea – all of our actions have direct and indirect consequences, some predictable, some entirely unforeseen, and we weigh up these outcomes with every decision that we make – including dietary choice. If we examine a number of the assumptions and recommendations within the current paper, it’s apparent that the negative consequences of the one-dimensional GHG focus may outweigh any benefits gained.

Although a regional approach was used to assess population health impacts, greenhouse gas emissions in the paper were based on reference values for various foods, with the inherent presupposition that all livestock production systems are equally productive and efficient. This is a fatally-flawed assumption. If we take beef as the example: in the USA, 90% of cows have a calf every year, cows first calve at 24 months of age and growing cattle are slaughtered at 15 months of age. By contrast, in Brazil, 60% of cows have a calf every year, cows first calve at 36 months of age and growing cattle are slaughtered at 42 months of age. Both systems are suited to the resources and market available, but have wildly different efficiencies. Consumption of a US-produced steak (16.7 kg CO2/kg) will therefore have a far lesser contribution to the average person’s carbon footprint than a Brazilian steak (62.0 kg CO2/kg).

All food have an environmental impact

Replacing milk, meat and eggs with plant-based foods (legumes, nuts, etc) is entirely possible, yet it does not occur at zero environmental cost. Every single food that we consume has an environmental impact, and although the greenhouse gas emissions associated with a unit of lettuce or beans may be less than pork or beef (asparagus is a notable exception), the land required to produce equivalent energy or protein from plants is significant.

We cannot simply remove cattle from the low-quality range and pastureland that they occupy in the majority of grazing regions and assume that we can plant brussels sprouts or soybeans instead. Only a small percentage of pastureland is productive enough to produce human food or fibre crops (8.0% in the USA and 10.8% in the UK). The fact that pastureland would have to be converted to cropland, releasing sequestered carbon dioxide to the atmosphere and increasing the use of fertilisers and irrigation water, was not accounted for in Springmann et al.’s study. Indeed, from where would we source fertilisers for crop production if we significantly cut meat consumption and thus livestock populations? Is an increased reliance on dwindling reserves of inorganic N, P and K really a sustainable solution?

Finally, and most importantly, cattle do not simply exist as a source of milk or meat. In many developing countries, immense cultural significance is placed upon livestock ownership and ruminant animals play a vital role in supplying draught power, capital assets and agricultural enterprise diversification. Should a single mitigating factor for reducing GHG emissions overcome the moral obligation to support and assist subsistence farmers in developing regions? It’s vital that we take a holistic view that encompasses environmental responsibility, economic viability and social acceptability in order to improve food system sustainability rather than simply focusing on one aspect of the problem. Rather than taking a whole-system approach to environmental and human health, the study by Springmann et al. is akin to amputating both legs in order to try and cure arthritis. Short-term pain may be reduced, but long-term suffering is inevitable.

Correlation vs. Causation – The Gluten-Free Example

My gluten-free tweetI’ve just been involved in that most pointless of activities – a Twitter argument. Entirely without value as neither side will admit defeat (or even concede ground) and it’s difficult to make rational, lucid points using words like “hereafter” and “whither” when the 140 character limit turns scientific discussion into a sea of “u r misinformed re: assoc w/glutfree diet” gobbledegook.

This debate was caused by me posting the photo to the left relating to the use of  “gluten-free” as a marketing term associated with supposedly healthier food. However, in the tweet below, the arguer (arguee?) demonstrated the commonly confused correlation vs. causation which appears to be the poster child for populist bandwagon-jumping science.

Coeliac tweetTheir follow-up tweet cited this website, which claims that 55 diseases can be caused by eating gluten, and there’s a link to a peer-reviewed New England Journal of Medicine paper to prove it. Excellent use of scientific literature to support the adoption of a gluten-free diet.

55 diseasesJust one tiny problem… the 55 diseases* listed in the table to the left are indeed associated with cœliac** disease in that people who are cœliac (0.3-0.8% of the population) often also suffer from a range of other conditions. However, this does not mean that anybody suffering from short stature, diarrhea, rheumatoid arthritis or congenital heart disease will have their symptoms relieved by adopting a gluten-free diet. Heck, if it did, we’d all be 6 feet tall and heart-healthy, right?

To put it another way, all penguins are black and white. Does that mean that all black and white objects are penguins? I have utmost sympathy for sufferers of cœliac disease as it must be a very difficult and painful condition. However, when a gluten-free diet is not only promoted being more healthy for the general population, but backed by willful misinterpretation of peer-reviewed data, it’s just another indication that we need better scientific education. Correlation not causation – rinse and repeat.

*Note that these are not all diseases per se, but that was how they were defined by the website 
** An autoimmune disease in which the small intestine is hypersensitive to gluten, leading to difficulty in digesting food. As a Brit, I’m using the English spelling as I find it too grammatically painful to omit the ligature (œ) 

Is Our Modern, Chemical-Laden, Twinkie-Guzzling Lifestyle Killing Us?

Burger4How often do we hear that we’re so much more unhealthy than our ancestors? That our modern chemical-laden diet is responsible for the fact that in 2010, the top three causes of death were heart disease, cancer and chronic airways disease? That if we only ate like our ancestors did (if you can’t pronounce it, it shouldn’t be in your food…) we’d have the secret to eternal life?

Let’s take a trip back to 1900 – the US contained 70 million US inhabitants, McKinley was president, and the first Hershey bar was introduced. Life was so much simpler without those pesky whipper-snapper millenials on social media and everybody lived till they were 95, passing with a smile on their face surrounded by their 17 children…or did they?

It’s a beautiful image – and an absolute fallacy. Life expectancy at birth in 1900 was 47.3 years. To put that into context, Michelle Obama, Keanu Reeves and Elle McPherson would already be dead, and Julia Roberts, Matt LeBlanc and Will Ferrell would be enjoying their final days of celebrity life. The low life expectancy was skewed by the high rates of infant mortality in 1900 – premature birth was the #11 most-common cause of death and up to 10% of infants died before their first birthday. Any child that made it past 5 years old had a pretty good chance of surviving – as long as disease didn’t set in – the top three killers in 1900 were pneumonia/flu, tuberculosis and heart disease.

Hold on… heart disease? Surely that’s a consequence of our modern, slothful, twinkie-guzzling lifestyle? Let’s move on to 1950, when most food was still organic, high-fructose corn syrup hadn’t yet been invented and the majority of beef and dairy cattle were grazed on pasture. Top three killers: heart disease, cancer, stroke.

There’s a reason why Mark Twain’s saying “lies, damned lies and statistics” gets quoted so often. In this case, the data is true. However, when we look at the statistics, i.e. the % of people killed by heart disease or cancer, those have indeed gone up. Why? Because very few people die of pneumonia, flu or TB. If we express something on a percentage basis, a decline in one factor means an increase in another. Simple 3rd-grade math. I hate to point out the obvious, but we’re all going to die – and there will always be a cause.

Many enthusiasts for the “Paleo” diet like to suggest that it must be a healthy lifestyle, because the average lifespan for our ancestors was the same as it is now – providing that they didn’t die in accidents, war or from infection. Way to go for those few ancestors who stayed in their cave and didn’t get attacked by a wildebeest! All that actually suggests is that a human body has a genetic potential for life of 75-80 years. Europeans who died from the Black Death in 1348-1350 weren’t genetically programmed to live shorter lives, they were just unlucky enough to run up against the microorganism Yersinia pestis. We can’t eliminate specific causes of death that don’t suit our theory to “show” that one lifestyle is more healthy than other – everything that we do, every single day will have some positive or negative effect on our eventual lifespan.

We’re lucky enough to live in a society where we have effective sanitation, a wide variety of nutritional choices, antibiotics, vaccines, x-rays and prenatal vitamins. In the US, nowadays only 6 babies die per 1,000 births compared to ~100 per 1,000 births in 1900. Average life expectancy is 78.1 years. If I were to follow the activist “correlation = causation” logic I could point out that in the past 114 years we’ve seen the introduction of cell phones; nuclear bombs; GMO-crops; rbST for dairy cattle; implants and antibiotics for beef cattle; and corn-fed beef… so these technologies must make us live longer!! Hooray!! Instead, I’ll just be thankful that I will be giving birth within the next week in a world where we have a safe, effective food supply and that my baby will have a far better chance of surviving than her great-grandparents did. Thank goodness for technology.