the French eat a lot of saturated fat and yet they have a low risk of heart disease. this is known as the French paradox. scientists have been interested in this phenomenon for decades.
this study looked at 40 countries. countries with higher intake of saturated fat and cholesterol had more deaths from coronary heart disease. the scientists thought this was pretty striking, especially since these countries were scattered all over the world, from North America to Europe, South America, Africa, Asia.
but this correlation was not perfect, there was significant scatter, the countries did not fall in a perfect straight line. the two biggest outliers were France, which fell under the trend line, so lower mortality, and Finland, which fell above the trend, so higher mortality. in fact, the scientists titled the study "differences in coronary mortality can can be explained by cholesterol and saturated fat intake in 40 countries but not in France and Finland".
so they set out to try and figure out why these two countries deviated the most from the norm. they went through dozens of dietary factors looking for any that could explain the differences. now, of course the causes don't have to be limited to dietary factors, and we'll come back to this in a minute.
okay, so what did the science find? several specific Foods correlated with coronary heart disease deaths. one example was milk and butter fat.
they plotted the 40 countries again as a function of milk intake this time, and now Finland and France fell much closer to the trend line and no longer seemed like such outliers. other dietary factors that also correlated well included vegetables, which were consumed four times more in France than Finland, unsaturated fats, for example polyunsaturated fats from vegetable oil were consumed eight times more in France than Finland. olives and peanuts were other examples, also consumed more in France.
the conclusion of the authors was that the French paradox might be explained by increased consumption of plant Foods, including small amounts of liquid vegetable oils and more vegetables. this idea is plausible but honestly, given the type of evidence that they relied on here, these raw comparisons between different countries, it was basically just a hypothesis. that's because when we compare different countries, there are so many differences, from genetics, to standard of living, to health care, to pollution, to culture etc etc etc, that it's just impossible to establish cause and effect from this type of evidence.
in fact, there have been many other theories put forward to try to explain the French paradox, from red wine to cheese to smaller portion sizes to gardening and exercise. some scientists even suggested that there was never a paradox at all, that it was all basically an illusion, that the French just started eating more saturated fat later compared to other countries and so the effect on heart disease just hadn't been observed yet, just hadn't gone up yet. this became known as the time lag hypothesis.
everyone and their mom had a pet theory, and they were all reasonable, and that's precisely because comparing entire countries to each other involves so many differences. this type of evidence is called ecological data or ecological associations, when we look at different countries or different populations somewhere in the world, like an indigenous population somewhere in the Amazon or in an island somewhere, and we try to look for associations, correlations between their behavior and their health. the blue zones are another famous example.
and ecological data is ranked lowest among the types of human evidence, right above experiments in lab animals, precisely because it's so confounded, because it has so many variables. now, ecological associations are super popular on social media, in general with a lay audience they're very engaging, because they just sound intuitive, it just sounds like it should be right. people in Japan eat a lot of food X and they're pretty skinny, they live long lives, so food X is probably healthy to eat.
this just feels like common sense, it just feels like it should be correct, but the truth is, scientifically these this type of association is notoriously unreliable. here's another example that really helps drive this point home: France has one of the highest smoking rates in the world, approximately a third of French people smoke. it's the highest rate of any country in western Europe.
even the United States, not exactly the poster child of health, is much lower. we could easily call this the French paradox. they smoke a lot and yet they have low risk of heart disease.
does that mean that smoking is not a risk factor for cardiovascular disease, for heart disease? of course not, we know it is from much stronger data sets. what it means is that heart disease is multifactorial, multiple things affect it, and you can have one thing be a little worse, if four or five are better the net effect is still going to be an improvement.
even if it's not great, cardiovascular disease is still a major cause of death in France, but it's going to look better than some other place that's doing even worse. exact same thing is true of saturated fat, it's one risk factor among several and just like with tobacco, we have much stronger data sets to ask what is the effect of saturated fat intake than these country to Country comparisons. the first level up from comparing entire countries would be to look inside a given country, look at different populations in the same country.
not a perfect experiment but less genetic and cultural variation than comparing France to Scandinavia or Japan or something like that. so this type of demographic study has been done in France, for example. they found that areas that had a lower risk of heart disease, like the region of Toulouse for example, in the south of France, if anything ate a little bit less saturated fat than other regions that had higher risk.
and of course there were also other differences, both dietary and otherwise. more wine consumption in the South, more fruits and vegetables, more cheese Etc. many differences.
so this would still be essentially an ecological Association, looking at these different regions. better, cleaner, but still tons of variables. where the rubber really meets the road is with cohort studies, where we can carefully adjust for dozens of variables, and of course with randomized controlled trials.
those are much stronger data sets, different league, and those data sets tell us that there is nuance, it matters how much saturated fat, it matters the source of saturated fat, it definitely matters what foods we're comparing the saturated fat to. but in general these data sets show that people eating large amounts of saturated fat have higher risks of heart disease and that moderating that saturated fat intake tends to reduce the risk of cardiovascular disease, especially compared to other foods that are more cardioprotective. so these types of evidence are in a different league from ecological associations.
if you're interested in an in-depth look at these data sets, we did exactly this type of overview in a previous video. and here's more dietary tips to lower your heart disease risk.
