I have found numerous problems in studies one hears about in the mainstream media, so I thought a thread on this topic would be valuable for those who read this newsgroup. I will update with future posts to this thread, but I want to begin the thread now, because I just read a study about how potatoes lower cholesterol and TGs - if you eat the entire potato. What does "low cholesterol" mean - here we have a language problem that you see all the time. In Ancel Keys' famous book, "Seven Countries" (Keys is regarded as the founding father of the heart disease/high cholesterol claim), he states that mortality was lowest in those whose cholesterol was between 200 and 220, and this was among people who were consuming quite a bit of oxidized cholesterol, though heart attacks were less frequent among the peoples of those nations who ate more antioxidant-rich foods, less homogenized dairy, etc.
I agree with Keys about the 200 to 220 range being best - in general. The problem is that if you do a study on people who are eating a particular kind of diet, let's say one rich in foods that act as oxidizing agents (e.g., refined, highly unsaturated oils), the potatoes may indeed by a very good choice, whereas for people on a diet that is low in foods that act as oxidizing foods (and abundant in antioxidant-rich foods), potatoes may not be especially healthy. In fact, if those people only have access to potatoes that are a bit green, then they may be quite an unhealthy choice.
Let's generalize: in order for this kind of study to be of any use, the researchers should specify what kind of diet the subjects were eating and what the potatoes were substitiuted for (assuming the subjects didn't just eat potatoes along with what they usually did). It would also be important to do all kinds of tests on the subjects to see if they already had pathological processes going on in their bodies, if they had high levels of markers for oxidative stress, etc.
In the case of potatoes, I don't see that they would do anything to perpetuate my health, though I could see that if someone ate a typical Western diet, and substituted boiled potatoes for cookies with farily high PUFA content, there could be the kind of results they report. Until more about all of these kinds of issues are known, it's not clear what to make of these findings.
This is why I propose a new nutritional science, one based on whole diets rather than introducing one food for several weeks (and this is another major problem with most of these studies, that is, they look for certain markers in the short term). Raw demographic data is already available, which went a long way towards making the case (for me) that saturated fatty acids can't be "bad;" otherwise, there would be very high rates of heart disease among coconut consuming Asians, rather than the very low rates we can see in the demographic data. However, to design an optimal diet in the context of availability and budget constrainst faced by many or most people, it likely would be necessary to do experiments on animals. Such experiments would be complete within a few years, would be inexpensive, and would not require any markers. We would simply note which diet allowed the animals to live longests. In science, especially these days, it seems like the simplest and cheapest things to do are the things that never get done! |
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