I love interacting with this informed and educated community of ours who take responsibility for own health, read and interpret scientific articles, ask intelligent and incredibly tricky questions and look at the world through a prism of human evolution. It’s really really cool. I also don’t own a television or read newspapers. I know, I am missing out on the vital information on the recent exciting advances in the field of laundry detergents, easily foldable exercise equipment and female hygiene products. But I’ll take my chances.
So when I was approached recently by an Australian reporter to comment on why saturated fat might not be as bad as everyone thinks, I was temporarily stunned. Everyone still thinks that? An hour-long lunch outside in the company of co-workers brought me back to reality. Listening to the less-than-lithe lady lecturing a younger employee that “pasta is perfectly healthy as long as you avoid creamy sauces and stick with tomato-based ones and add psyllium husks to increase fibre” plunged me back to earth from the AHS12-induced heights.
Oh boy. On this planet, margarine is still a health food.
So I thought I’d write down some thoughts on fats, why we still need to talk about them, the strength of evidence and where we go from here. The article ended up being published at The Age and I was amused to see our hour-long phone conversation and the exchange of several emails with attached studies reduced to one sentence quoted from me, but I am not complaining since I think the article was quite well-balanced and hopefully gives people some food for thought. Here is the link.
Don’t all scientists and doctors agree that saturated fat is bad?
My main gripe with conventional advice to reduce saturated fat in the diet is that it makes it sound that everyone in science and medicine agrees that it is the right thing to do. They say “scientists” and you imagine a group of nerdy-looking men and women in lab coats and glasses with clipboards, all nodding in unison: “Saturated fat will kill you”.
Sorry, no. Far from it. In the year 2012 we still run trials on dietary fat and its effect on mortality, cardiovascular disease and weight. In fact, a Pubmed search on “dietary fat” yields close to 700 article from 2010 to present date.
If “saturated fat will kill you” is a done deal why do all these folks get research grants and waste years of their life on the pointless pursuit of the truth that has long been discovered and incorporated into every government-led nutrition advice?
And yet, the consensus is farther away than ever. Nutrition and Metabolism Society publishes critiques of the American Dietary Guidelines, as well as scores of papers on the subject. Then there is THINCS, The International Network of Cholesterol Skeptics, which really sounds like an evil mad scientist organisation from a Bond movie, but in fact has respected members like a biochemist Dr Mary Enig and a scientific researcher Dr Uffe Ravnskov.
Not to mention a fine gathering of clinicians, scientists, nutritionists, researchers, physiotherapists, bloggers at Harvard Law School this year for 2012 Ancestral Health Symposium, most of whom seemed to think that bacon is rad and margarine is bad.
Can you refute XYZ study and the rest of the body of evidence on saturated fat?
Yawn. I have no intention on memorising every study conducted in the last 50 years, no matter how bad or good they are. We have been eating fat, lard, meat, eggs, butter, ghee, coconut oil for thousands of years. I think the burden of proof lies on those who say that these traditional foods have been our silent killer all along. All I can do is to politely present the vast body of scientific evidence that does not support the lipid hypothesis (YES! IT IS STILL A HYPOTHESIS!)
Sarcasm alert. Lipid Hypothesis 2.0 = we have come to realise that total fat intake has no bearing on heart disease or weight (sorry! Our bad!) But it’s all about the type of fat. There are only 2 types of fat: saturated (=evil, comes from animals, eating animals is bad, you immoral cruel self-serving glutton) and unsaturated (=pure good, comes from vegetables, like cottonseed, soybean, canola and sunflower, botany be damned). Substituting unsaturated for saturated fat is the real reason why we are healthier, thinner and fitter than thousands of generations of traditional cultures because they couldn’t work out how to get 10% of their daily calories from PUFA, suckers.
Several studies have shown improvement in CV markers and mortality when saturated fats were replaced with PUFA. Regardless of how good/bad sat fats are, shouldn’t we make the substitution just in case anyway?
This is a very common reasoning from many educated doctors and academics. They are now aware that sat fats are not much of a problem. Great. But what’s the harm in tinkering our diets if all we have is improvement, right?
I have a real problem with a blanket advice to increase PUFA in general as if they are all the same. PUFA are not all created equal, they have different physiological functions and effects on the body! (go back to basics). At the very least they should be differentiated into omega-3 and omega-6. However, even that’s too simplistic.
If you are planning on dividing fats on the basis of the biochemical structure and biological function, you have just only scratched the surface. Behold! All saturated fats are actually not the same either. Lauric fatty acid is metabolised differently and has different effects on serum lipid profiles than stearic. Even omega-3 are not a homogenous group (gasp!). The intake of the shorter-chained ALA (alpha-linolenic acid) does not come close to providing the same benefit as the long-chained DHA due to inefficient conversion.
Jacobsen’s analysis of 11 cohort studies, quoted in the article as the final proof of the miracle qualities of PUFA, showed that substituting PUFA for SAFA seemed to reduce CV events and mortality. However, simplification, as usual, can only take you this far. The analysis lumped omega-3 and omega-6 PUFA together and did not take into account the deleterious effect of trans fatty acids separately from SAFA.
“Linoleic acid selective PUFA interventions produced no indication of benefit but rather a fairly consistent, but non-significant, signal toward increased risk of coronary heart disease and death. ” (Kuipers ER al, 2011, hyperlinked above)
That’s what happens when you simplify a complex concept. Why? Because the public are so dumb they won’t get it? Because 2 types of fat is quite enough to remember? And to make things even more visually and conceptually appealing let’s represent them as ying and yang, bad and good, dark and light?
So you have some studies, “they” have some studies. How do lay people know who to trust?
As much as I respect Evidence Based Medicine, I am well aware of its limitations. You can pull apart every study, point out the confounders, small sample size, confirmation bias, lack of double-blinding, the grant approved by a completely impartial third party with key investments in related area. Let’s not reduce the process to “Mine is bigger than yours.”
“Nothing in biology makes sense except in the light of evolution“. Repeat this 5 times before going to bed every night.
How much omega-6 was available in our diet as Homo sapiens for 2 million years up to the advent of industrial processing? How much oil can you get out of a soybean without the benefit of extraction chemicals?
Aaaaaaah! Would you just tell me how much PUFA/SAFA/Carbs I should be eating?
Talking about macronutrients (fatty acids, carbs, etc) is useless unless it applies to food. If the advice to increase PUFA translates into “eat more fish” I will be the first one to shout it from the rooftops! But what if it translates into “eat more peanut butter”? Still PUFA! But are you going to get the same benefits? You don’t need to read an insightful review by Christopher Ramsden on omega-3 vs omega-6 to know that peanut butter ain’t gonna make you healthier than salmon. But sometimes we really really want to believe it. And deluding ourselves is oh so easy when somebody in a position of authority gives you the green light.
Focusing too much on macronutrients is what allowed abominations like “low fat banana bread” to become a healthy morning tea snack. The “reductionism” approach has successfully indicted natural foods such as eggs, coconut, avocado, butter. At the same time we have low fat sausage rolls, sugary cereal, margarine and other foods devoid of any nutrition, riding on the coat tails of the lipid hypothesis 2.0.
One of the benefits of using the evolutionary approach is that it allows you to make rational decisions about your life choices without having to double-check them with Pubmed. And it doesn’t involve re-enactment of Paleolithic times, although heaven knows, I find some modern social conventions really tedious (like people requesting to know how I am going on a Monday morning prior to my first cup of coffee). As the opponents of the Paleo approach correctly point out, we don’t really know what our ancestors ate. But I sure as hell know what they DIDN’T eat: excessive amounts of sugar, grains, seed oils and other industrially produced food-like substances. Not even almond flour cupcakes. Sorry.
Regulating your fat intake is easy: eat fish, seafood, meat (preferably grass-fed), eggs, some nuts, seasonal fruit and veggies.
Go back to eating food, not labels.