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.
“Try to cut down on the salt.”
I’m sure many people have gotten this well-meaning piece of advice from their doctor, especially if their blood pressure is a little bit high. It ranks up there with not smoking or drinking alcohol and avoiding red meat, saturated fat, and sugary drinks as one of those things we’re told to do if we don’t want to die prematurely. It is actively promulgated by government health authorities all over the world, including the NHS in the UK and the FDA in the US.
In my previous post on the covid pandemic I mentioned that the body’s main defence against viruses is T-cells, not antibodies, and that the only reason we test for antibodies instead in clinicial practice is because it is easier and cheaper. I also ventured a hypothesis that the levels of population immunity are much higher than is being found in the antibody tests, and that this is because lots of people who don’t have antibodies do have covid specific T-cells. It turns out that this hypothesis is supported by new evidence.
A new study has just been published in JAMA (the Journal of the American Medical Association) that seeks to answer this question definitively. This subject has been somewhat controversial, because observational studies have tended to show a positive effect, while randomised clinical trials have failed to show any effect. Usually you would trust the trial data more than the observational data, but these trials were all relatively short (generally a year or less), had relatively small study groups, and often used quite low doses of vitamin D.