I noticed an interesting article in the British Journal of Sports Medicine (BJSM) recently. It sought to determine the explanation for the ‘paradox’ seen in Masai tribesmen in Kenya can consume relatively large quantities of animal fat (especially in the form of milk, meat and blood), and have stunningly low rates of heart disease. We all know that saturated fat causes heart disease, right, so the question some have asked for decades now is how the Masai can eat so much of this stuff will so little apparent impact on their cardiac health. The explanation has typically been that the Masai are protected from heart disease by certain genetic factors. In this BJSM article, scientists put forward a different theory: that the Masai’s regular and prolonged physical activity (mainly in the form of walking) and low body weight affords them protection from the supposed hazards associated with their high-animal fat diet.
Some of you reading this may find this topic vaguely reminiscent of the so-called ‘French paradox’, whereby some inhabitants of France consume very high levels of animal fat but appear to enjoy, again, really quite low rates of heart disease. If you’re familiar with phenomenon, then you may also know that the oft-quoted explanation for this apparent paradox is the consumption of red wine which, we are told, serves as an antidote to the fat-filled diet of the French.
However, before we go looking for explanation for paradoxes, my suggestion would be first to examine whether there is indeed a paradox to be explained. The paradox seen is both the Masai and the French assumes that animal (and saturated fat, particular) has the ability to clog up our arteries and precipitate heart disease and perhaps other cardiovascular conditions (e.g. stroke) as well. But is this really the case?
From a theoretical perspective one could argue that animal fat should not be the dietary spectre its generally made out to be. Why? Because there is quite a body of evidence which suggests that it’s been in our diet forever, and therefore is something we should be quite well adapted to by now. However, it’s not enough to rely on this sort of common sense, we also need to look to the science too.
Back in February I reviewed the evidence surrounding saturated fat and cholesterol. You can read that blog post here. In summary, what the evidence shows is that:
1. Saturated fat consumption does not have strong links with risk of heart disease
2. There is little (if any) good evidence that eating less saturated fat reduces the risk of cardiovascular disease or overall risk of death
This may seem like nutritional heresy, but it is, remember, utterly in keeping with the theory that the foodstuffs we’ve had for the longest in our diet are the ones we’re best adapted to and are likely to be the most appropriate foodstuffs for our consumption too.
Or course, there’s another side to this coin, in that authors of the BJSM study note that the typical Masai diet is not just high in fat, but low in carbohydrate. I recently wrote about the issue of carbohydrate and cardiovascular health here.
You will read here how certain carbohydrates have the capacity to cause considerable disruption of blood sugar levels, and their consumption may induce changes that would be expected to increase the risk of cardiovascular disease. The review that forms the focus of this blog post concludes that eating a diet rich in highly disruptive carbohydrates (high glycaemic index and/or glycaemic load foods) is associated with a 20 – 100 per cent increased risk of cardiovascular disease.
In other words, not only may the Masai’s low risk of heart disease not be a paradox at as far as animal fat consumption is concerned, it might also be related to the relative paucity of carbohydrate in their diet too. The physical exercise may indeed be helping to reduce their risk of heart disease, of course, but we don’t necessarily need this lifestyle factor to explain how it is that individuals eating a high- fat, low-carb diet are at the same time at relatively low risk of heart disease.
Mbalilaki JA, et al. Daily energy expenditure and cardiovascular risk in Masai, rural and urban Bantu Tanzanians. Br J Sports Med. 2008 Jun 3. [Epub ahead of print]