Barts-MS rose-tinted-odometer: ★★★
Since my rather neutral “#DIETSPEAK: IS THERE AN IDEAL MS DIET?” post last week, in which I refuse to support any particular MS diet I have had a torrent of social media abuse about my position. Intriguingly, many people out there have bought into the falsehood that saturated fats are bad for you and some commentators even believe that saturated fats cause MS. The evidence is clearly to the contrary for the former and for the latter the evidence is just not there to draw any causal inferences. In fact, as saturated fat consumption has gone down the incidence and prevalence of MS has increased. This alone indicates that saturated fat consumption cannot be the cause of MS.
John Maynard Keynes, the famous British economist responsible for ‘Keynesian economics’, is often quoted as saying: “When the facts change, I change my mind. What do you do, sir?”.
The claim that saturated fat is bad for health was promoted by the now-discredited physiologist and nutritionist Ancel Keys. His theory was based on his ‘Seven Countries Study’, which has now been discredited with several commentators suggesting that some of the data was made up. There is evidence that of 22 countries that he had data for, he cherry-picked 7 countries so the data would fit and prove his hypothesis. Despite this, he and his collaborators managed to change the dietary guidelines of the world, recommending a low-fat diet to counteract the cardiovascular disease epidemic. Tragically, the rest is history.
The low-fat diet, in particular the low-saturated fat diet, resulted in a caloric switch to carbohydrates, which has seen obesity rates soar and contrary to what was expected cardiovascular disease rates have increased. It is now clear that Ancel Keys was heavily conflicted and was supported by the food industry. Yes, the food industry managed to influence a change in dietary guidelines that have killed tens of millions of people prematurely. I predict that when the dust settles on this issue the food industry will be judged to have behaved much worse than the tobacco industry.
The good news is that the facts have changed and several recent meta-analyses have been unable to find any evidence that saturated fats are bad for you (please see review below). The studies showing saturated fats are associated with poor health outcomes are confounded by other factors for example the consumption of processed carbohydrates.
To address the point that saturated fats cause MS you need to go back to causation theory and apply epidemiological principles. I have addressed this topic several times in the past on this blog, mainly in relation to EBV as a potential cause of MS. To prove or disprove causation you have to satisfy as many of the following nine criteria as possible.
1. CONSISTENCY AND UNBIASEDNESS OF FINDINGS
2. STRENGTH OF ASSOCIATION
3. TEMPORAL SEQUENCE
4. BIOLOGICAL GRADIENT (DOSE-RESPONSE RELATIONSHIP)
6. COHERENCE WITH BIOLOGICAL BACKGROUND AND PREVIOUS KNOWLEDGE
7. BIOLOGICAL PLAUSIBILITY
8. REASONING BY ANALOGY
9. EXPERIMENTAL EVIDENCE
When you apply these nine criteria to saturated fat consumption none of them is fulfilled. I, therefore, can conclude that saturated fat consumption is not the cause of MS. On other words, the data disproves the hypothesis.
Another perspective that you can use to tackle this problem is an evolutionary medicine perspective and to look at how our ancestors evolved and what diets they ate. It is clear that our ancestor’s diets were high in saturated fats and as the history of MS suggests it is a relatively new disease it cannot be caused by saturated fat. In fact, if you want to finger a dietary factor you would point at sugar and processed carbohydrates rather than saturated fats.
I wrote a piece on Medium to explain why low-fat diets are potentially bad for you. You may find the evolutionary medicine approach to diet of interest; I think it may prove to be very relevant to MS.
Astrup et al. Saturated Fats and Health: A Reassessment and Proposal for Food-Based. J Am Coll Cardiol 2020 Aug 18;76(7):844-857. doi: 10.1016/j.jacc.2020.05.077. Epub 2020 Jun 17.Recommendations: JACC
The recommendation to limit dietary saturated fatty acid (SFA) intake has persisted despite mounting evidence to the contrary. Most recent meta-analyses of randomized trials and observational studies found no beneficial effects of reducing SFA intake on cardiovascular disease (CVD) and total mortality, and instead found protective effects against stroke. Although SFAs increase low-density lipoprotein (LDL) cholesterol, in most individuals, this is not due to increasing levels of small, dense LDL particles, but rather larger LDL particles, which are much less strongly related to CVD risk. It is also apparent that the health effects of foods cannot be predicted by their content in any nutrient group without considering the overall macronutrient distribution. Whole-fat dairy, unprocessed meat, and dark chocolate are SFA-rich foods with a complex matrix that are not associated with increased risk of CVD. The totality of available evidence does not support further limiting the intake of such foods.