by Grant Schofield and Helen Kilding
Addendum note from Grant: This post has generated an enormous amount of debate – see the comments section. Its interesting as the authors of this study came back into the debate early.
Another study, this time it’s my colleagues much closer to home in New Zealand, and they received quite a bit of media space from it. The authors sought to estimate the potential impact on cardiovascular health of modifying dietary intake of saturated fat across the New Zealand population, and whether this would be appropriate and feasible.
They decided that while there was no evidence that fat intake affected health, substituting saturated fats with polyunsaturated fats would be of use and is “feasible” for the health of New Zealanders.
Here’s the paper. “Review of the evidence for the potential impact and feasibility of substituting saturated fat in the New Zealand diet (Rachel H. Foster, Nick Wilson, Burden of Disease, Epidemiology, Equity and Cost-Effectiveness (BODE3) Programme, Department of Public Health, University of Otago – Wellington, New Zealand).
They concluded that “Replacing 5% of daily energy consumed as saturated fat with polyunsaturated fats would be expected to reduce cardiovascular events by about 10%.”
Here’s what the media made of it - The New Zealand Herald, and Stuff.co.nz
And I got more than a few questions from readers….for example:
What’s your take on this study? (see attached)
Many of the fats they mention as bad I have been eating for the past two months and have lost weight and improved cholesterol! This is an actual result and if anything by default resulted in me consuming less of their so called good fats i.e canola oils, polyunsaturated oils etc.
No wonder it is hard for people to make informed decisions about diet with so much conflicting information. End of the day I decided to see for myself and make myself the test subject on a LCHF diet and continue to be thankful I did.
So what do we make of all this? First, they actually found no association between fat intake and disease outcomes in their meta-analysis. So great, fat isn’t a risk. But they did conclude that because replacing saturated fat reduces risk, that saturated fat must therefore be a risk factor.
I guess they haven’t considered the latest meta analysis in the American Journal of Public Health (2013) ”Food Sources of Saturated Fat and the Association With Mortality: A Meta-Analysis “. This specifically looks at saturated fats. They show very limited evidence for most saturated fats foods having any association with CVD or cancer. Probably processed meat is the strongest association. In this sort of food product, saturated fat isn’t the only metabolic ingredient.
Nor have they considered that actual experimental evidence through randomized controlled trials (there are more than 20 now) does not show a harm for increasing saturated fat intake in LCHF diets. All the “established” cardio-metabolic risk markers show very favorable outcomes compared with all other diets. No long term outcomes, but these are well known and regarded proxies.
The recently published Sydney Heart study data shows that exactly the opposite happened back in the 1970s, when they replaced saturated fat with polyunsaturated fat and saw things get worse. Here’s the BMJ editorial on this. And here are some results:
“Participants were randomly divided into two groups. The intervention group was instructed to reduce saturated fats (from animal fats, common margarines and shortenings) to less than 10% of energy intake and to increase linoleic acid (from safflower oil and safflower oil polyunsaturated margarine) to 15% of energy intake. Safflower oil is a concentrated source of omega-6 linoleic acid and provides no omega-3 PUFAs. The control group received no specific dietary advice.
Both groups had regular assessments and completed food diaries for an average of 39 months. All non-dietary aspects of the study were designed to be equal in both groups.
The results show that the omega-6 linoleic acid group had a higher risk of death from all causes, as well as from cardiovascular disease and coronary heart disease, compared with the control group.”
Nor have they considered almost all of the growing mechanistic evidence that metabolic issues, including CVD, are inflammatory based and the evidence points strongly to a myriad of interacting pathways, from gut microbiome, to sugar, to simple carbs, to the stress axis, to VLDL and triglycerides through the liver etc etc. The direct effect of dietary saturated fat is not clear in any of these mechanisms and unlikely to be a factor.
Overall, the evidence from the association studies is weak, equivocal, or inconsistent, depending on what term you like best. Experimentally and mechanistically it doesn’t stack up. Come on guys, are you doing your reading? It’s not good enough when there is such a broader amount of evidence. Your study doesn’t lead to a rationale for reducing saturated fat and replacing it with polyunsaturated.
Worse still, you’re promoting the use of manufactured vegetables oils which are high in Omega 6 and likely to be inflammatory, adding further to the problem. These oils are also quite unstable and easily oxidized further, adding to metabolic problems. Saturated fat is not.
Avoiding fat will likely mean eating more carbohydrate. For many, this will further dysregulate their carbohydrate metabolism and make them more insulin resistant resulting in a downward cycle with all the direct and indirect effects of hyoerinsulinemia. These guys just haven’t even thought that the active metabolic ingredient in their weak epidemiology might be something else which they haven’t or can’t control for…..insulin-raising carbs.
WHAT I THINK WE SHOULD THINK ABOUT WITH FAT:
- Fat contains loads of calories
- Fat is an essential nutrient
- Highly processed fats are inflammatory
- Good quality whole foods, including loads of vegetables, are good for you. Their fat content appears not to harm you.
- Omega 3 fats are good for you. These are poly unsaturated so if that is what they are talking about then great. But these guys go on to talk specifically about manufactured seed oils – these are not good.
- In high carb, insulin-provoking diets, fat seems to add to the insulin response. This seems to be worse in people who are insulin resistant. By itself, fat is metabolically benign, at least as far as insulin response is concerned. A good reason to avoid the standard American diet.
- Processed meats are likely to be bad for you. I’m not sure if it’s the actual fat and I’m not sure what the mechanisms might be – inflammatory? We may never know if they are for sure because no one is likely to run an experimental trial where people get a long dose of processed meat.
Take home messages:
- Don’t believe everything you see in a scientific paper. Sometimes they go past the evidence.
- Carry on eating fat, hopefully in the absence of processed and simple carbs as they may harm you in combination.
How did fat get such a bad name in the first place?
We’ve been brainwashed in to thinking that when we eat saturated fat it goes straight into our bloodstream, instantly bonding to the inside of our arteries, eventually clogging them up completely. This is bullshit. Atherosclerosis is caused by oxidised LDL particles penetrating our arterial walls, inciting inflammation and damaging the arterial tissue. And what increases LDL particle number?
- Insulin resistance and metabolic syndrome
- Poor thyroid function
- Leaky gut
Let’s look at that list again…..no mention of dietary intake of saturated fat.
And when we talk about saturated fat, everyone always wants to talk about cholesterol. Dietary cholesterol does not affect total blood cholesterol. In fact, when we do eat cholesterol, our body makes less of it to keep our blood levels in balance.
So even if eating fat doesn’t result in CVD, won’t eating fat make us fat?
No again. As we’ve said before, fat doesn’t make you fat. Fat is very satisfying, especially when paired with low-carb eating. A nice steak rippled with fat is far more filling than some crusty bread spread with butter. You’ll eat a decent piece of the former and be satisfied but could easily polish off half a loaf of the bread with a good helping of butter and still be hungry. It’s difficult to overeat on a high-fat, low-carb diet.
Our bodies want to use fat for energy, but when we eat fat in the presence of large amounts of dietary carbohydrates, it makes it difficult to access fat for energy. On the flip side, dietary fat in the presence of low levels of dietary carbohydrates makes it easier to access fat for energy. It’s also easy to overeat fat and carbs together – think hot chips, buttered toast, milk chocolate.
And let’s think about farming for a second….how do you fatten cattle? You feed them lots of lots of grass (a carbohydrate). According to a recent post on Christine Cronau’s Facebook page, “70 years ago, farmers tried to fatten their livestock with saturated fat. It backfired! The pigs lost weight and became more active. Of course, the farmers weren’t silly enough to persist with something that didn’t work, yet our conventional health professionals have insisted on doing so!” I’ve tried to source more detail on this but have drawn a blank so far.