As I have written this series of blogs I have noted with interest the comments that people have come up with, and the discussions that have followed. It is interesting, though not unexpected, that almost everyone has focussed, almost entirely, on diet, and little else.
There are those who are utterly convinced that the cause of cardiovascular disease is a high carbohydrate diet. There are others who argue that this is not the case. There are also many who promote various dietary supplements, and vitamins and suchlike.
Within the mainstream, the discussions also seem to focus almost entirely on diet [and the effect diet has on cholesterol levels in the blood]. Over the years the ‘experts’ have moved on from cholesterol in the diet to saturated fat, to saturated/polyunsaturated ratios, to Omega-6 to Omega-3, to even or odd chained saturated and polyunsaturated fats… and on and on and on.
Sixty years ago Ancel Keys proposed the diet-heart hypothesis of cardiovascular disease. He started by stating that cholesterol in the diet raised cholesterol levels, which then cause cardiovascular disease. He ended up stating that saturated fat raised cholesterol levels and, well, you know that last bit. At least he only changed direction once.
Juhn Yudkin was Keys’ main rival in the diet-heart stakes. He stated that is was sugar in the diet that was the culprit. Unfortunately, Ancel Keys was a far better political operator and self-publicist. So he crushed Yudkin and won the argument. At least he won it for a while. Now, more and more people are saying that Yudkin was right all along.
Whatever you may think of Ancel Keys, and my thoughts should never be put down on paper without significant filtering out of swear words, he certainly managed to set the agenda for all discussions that followed. The agenda being that cardiovascular disease is caused by ‘something’ in the diet. Thus, diet has become playing field, and almost everyone fights here. It is this in the diet, not that. It is that, not this.
The problem I have here is that I do not believe that diet has much of a role to play in cardiovascular disease. There is evidence that vegetarians can live long, long and healthy lives. There is evidence that meat eater live long, long and healthy lives. In the West, we are eating more and more sugar and carbohydrate and the rate of cardiovascular disease falling. France maintains a very high saturated fat diet, and their rate of cardiovascular disease also falling.
I read the Blue Zones, which looked at people who live the longest, and I can see nothing whatsoever in the diet that links them together. Although the authors made various attempt to suggest that a vegetarian diet was healthy, the evidence does not stack up to support their assertions.
Of course I will be told that is not a simple as this. We need to look at sub-fractions of monounsaturated fats, or the glycaemic index, or grass fed this, or grain fed that or the specific impact of fructose on lipogenesis and insulin production…. On and on it goes. I sometimes feel that a complexity bomb has been thrown at CVD the purpose of which is to fractalise the debate.
Big fleas have little fleas,
Upon their backs to bite ’em,
And little fleas have lesser fleas,
and so, ad infinitum.
If there is anything, powerfully linking diet to cardiovascular disease, then I cannot see it. The only link that I can see is that people who eat a higher carbohydrate diet are more likely to become obese and develop diabetes. Or, perhaps I should say, develop diabetes and become obese. [A comment I may have to explain at some point].
As people who have diabetes are more likely to die of CVD then it seems highly sensible for those with diabetes to reduce carbohydrate consumption. This is also true of those who seem to be relatively intolerant to carbohydrates. Perhaps I should rephrase this as ‘people who tend to produce more insulin in response to diabetes.’
Blast, again here I am finding myself dragged into the diet debate. It seems impossible to release the discussion from this intellectual black hole. The meme is firmly entrenched. CVD is primarily to do with diet. Ancel Keys may be, posthumously, about to lose the argument on saturated fat However, he certainly succeeded in anchoring almost all discussions within the wider hypothesis that CVD is primarily due to diet.
It is not.