Why human, not mice, studies are the most appropriate for judging the effects of diet on human health

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I’ve said before that while I don’t believe any one diet is ideal for everyone, I favour diets lower in carb and higher in protein (and also fat) than the diets traditionally recommended as ‘healthy’. Such diets generally give better results for weight loss than, say, low fat diets. They also tend to be extremely useful in the management of diabetes and metabolic syndrome. Also, even for those not afflicted by these conditions, they usually lead to changes in physiological and biochemical parameters that are associated with a reduced risk of heart disease such as lower levels of blood sugar and blood fats (triglycerides) as well as higher levels of ‘healthy’ high density lipoprotein (HDL) cholesterol. In my view, anyone with a special interest in the field of nutrition would have to be unaware of the research or choose to ignore it not to admit to the broad merit in lower-carb eating for human health.

Notice I put ‘human’ in the last sentence because this week saw a study which appears to call into question the safety of low-carb diets that was actually performed in mice. You can read about this study on the BBC website here. In this study mice which have been bred to be particularly susceptible to atherosclerosis were used (atherosclerosis is the ‘furring up’ process in the arteries that can lead to heart attacks and strokes). The mice in this experiment were fed one of three diets. The diets were:

1. Regular mouse chow
2. A diet comparable with a standard ‘Western’ diet in terms of fat and cholesterol
3. A lower-carb, higher protein diet containing levels of fat and cholesterol comparable to diet 2

The study, which went on for 12 weeks, found that the Western diet produced 9 per cent more atherosclerosis than the regular mouse chow diet. The lower-carb, higher protein diet, however, appeared to give even worse results (15 per cent higher than the mouse chow diet).

Not surprisingly, this study has been covered with a ‘low-carb diets are bad for the heart’ sort of message. Some researchers have tried to ‘prove’ this over the years, despite overwhelming evidence which shows that, if anything, lower-carb diets superior for cardiovascular health. Unable to find any decent human data to support the concept that low-carb diets are unhealthy, it seems some researchers will go to extreme lengths to demonstrate supposed hazards in animal models.

This study appears to be an example of this. It is vaguely reminiscent of the studies performed decades ago in which rabbits fed stacks of cholesterol were found to develop atherosclerosis. But rabbits are herbivores, and don’t have cholesterol naturally in their diet. No wonder, then, that feeding it to them in excess might not do them much good.

Mice are ostensibly herbivorous too, and by virtue of that eat a diet rich in carbohydrate. Feeding them a low carbohydrate is therefore taking them far away from the diet they are best adapted to, especially if it offers super-high levels of protein (45 per cent of calories) that mice would not be accustomed to eating. Come to think of it, humans are not be accustomed to eating such a protein-rich diet either.

Seems to me, then, that these researchers chose an inappropriate animal model to test their theory on, and then fed the animals an inappropriate diet to boot. These actions suggest that the researchers were doing what they could to design an experiment to produce a desired outcome. We get a little sense of that when it is revealed that the researchers decided to investigate their [low carb diets] impact on the cardiovascular system after hearing of reports of people on the diets suffering heart attacks. I wonder whether it ever occurred to these researchers that legions of people are dropping down dead ever day while following low-fat diets. Perhaps start here?

You can see from the article that I’ve linked to, that lead researcher Anthony Rosenzweig said the findings were so concerning to him that he decided to come off the low-carb diet he was following. I see, so this scientist has decided to turn his back on a huge stack of human evidence on the basis of one quite inappropriate animal study. The fact that it was his own study does not mitigate against the fact that this seems like a really dumb decision on his part.


1. Foo SY, et al. Vascular effects of a low-carbohydrate high-protein diet. Proceedings of the National Academy of Sciences Epub 24th August 2009

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