Considering how much misinformation is currently floating around in the area of health and medicine, I thought it might be useful to write an article about how to read and understand scientific studies, so that you can feel comfortable looking at first hand data yourselves and making your own minds up.
UPDATE 14th November 2020: In light of the recent increase in hospitalizations and deaths during October and November in Sweden, I no longer believe that Sweden reached a state of herd immunity during spring. The text below represents my thinking on the 19th of September, when I wrote the article, and doesn’t represent my current thinking. It is clear that a significant level of population immunity did build up during spring and summer, since the rise in hospitalizations has been much slower during the autumn than it was during the spring, and also seems to be stabilizing at a much lower level. However, the level of population immunity is clearly not as high as I previously thought. The reason I made this mistake is that the early evidence on covid suggested that it was not behaving in a seasonal manner. This caused me to underestimate the seasonal effect of summer to push down infections, which caused me to overestimate the level of population immunity that had built up during spring. It is now clear that covid is a highly seasonal virus.
In an earlier article we debunked the claim that exercise will help you lose weight. What about whether exercise will help you live longer? Now, don’t get me wrong, I am certainly not anti-exercise. There are lots of studies showing that exercise has many and varied health benefits, from improving muscle strength and balance, to decreasing the risk of fractures and delaying the onset of dementia. But will it help you live longer? And if it does, how much exercise should you be getting to maximize longevity? Are the famous ”10,000 steps a day” and ”half an hour a day” recommendations enough or should you be doing more than that?
Traditional diet advice over the last fifty years, still espoused by most health authorities around the world, holds that if you want to lose weight, you need to cut down your fat intake. In the last few decades, a number of alternative diets have sprung up claiming that you should instead be cutting down your carbohydrate intake. These include the LCHF, Atkins, paleo, and more recently the ketogenic diets. But what do the randomized controlled trials say? Should you cut down on fat or carbs if you want to lose weight?
A new article has just been published in the Journal of Steroid Biochemistry and Molecular Biology looking to see if an oral vitamin D supplement can be used to cure covid-19. Considering that vitamin D is cheap, widely available, and safe, it would be pretty miraculous if that turned out to be the case.
Is there any life left in the cholesterol hypothesis (a.k.a. the lipid hypothesis)? Is there anything left for serious scientists to cling to or is time for its mouldering corpse to end up on the trash heap of medical history, alongside lobotomy, bloodletting and the theory of the four humors? I was asked this question by a reader of this blog recently, and as it happens, a systematic review was recently published in Evidence Based Medicine (my favorite medical journal, mainly because it is edited by the brilliant Dr. Carl Heneghan) that definitively answers this question, so I thought it would be interesting to go through what the evidence says together.