Vitamin D and Cholesterol: The Importance of the Sun (2009) by David Grimes, a British doctor, contains more than a hundred graphs and tables. Most of the book is about heart disease. Grimes argues that a great deal of heart disease is ...
Vitamin D and Cholesterol: The Importance of the Sun (2009) by David Grimes, a British doctor, contains more than a hundred graphs and tables. Most of the book is about heart disease. Grimes argues that a great deal of heart disease is due to too little Vitamin D, usually due to too little sunlight. I recently blogged about other work by Dr. Grimes — about the rise and fall of heart disease.
Part of the book is about problems with the cholesterol hypothesis (high cholesterol causes heart disease). One study found that in men aged 56-65, there was no relationship between death rate and cholesterol level over the next thirty years, during which almost all of them died (Figure 29.2). There is a positive correlation between death rate and cholesterol level for younger men (aged 31-39). The same pattern is seen with women, except that women 60 years or older show the “wrong” correlation: women in the lowest quartile of cholesterol level have by far the highest death rate (Figure 29.5). A female friend of mine in England, who is almost 60, was recently told by her doctor that her cholesterol is dangerously high.
The book was inspired by Grimes’ discovery of a correlation between latitude and heart disease: People who lived further north had more heart disease. This association is clear in the UK, for example (Figure 32.4). Controlling for latitude, he found a correlation between hours of sunshine and heart disease rate (Table 32.3): Towns with more sunshine had less heart disease. No doubt you’ve heard that dietary fat causes heart disease. In the famous Seven Countries study, there was indeed a strong correlation between percent calories from fat and heart disease death rate (Figure 30.2). You haven’t heard that in the same study there was a strong correlation between latitude and dietary fat intake (Figure 30.8): People in the north ate more fat than people in the south. The fat-heart disease correlation in that study could easily be due to a connection between latitude and heart disease. The correlation between latitude and heart disease, on the other hand, persists when diet is controlled for.
Grimes convinced me that the latitude/sunshine correlation with heart disease reflects something important. It is large, appears in many different contexts, and has resisted explanation via confounds. Maybe sunshine reduces heart disease by increasing Vitamin D, as Grimes argues, or maybe by improving sleep — the more sunshine you get, the deeper (= better) your sleep. Sleep is enormously important in fighting off infection, and a variety of data suggest that heart disease has a microbial aspect. As long-time readers of this blog know, I take Vitamin D3 at a fixed time (8 am) every morning, thereby improving my Vitamin D status and improving my sleep.
Grimes and his book illustrate my insider/outsider rule: To make progress, you need to be close enough to the subject (enough of an insider) to have a good understanding but far enough away (enough of an outsider) to be able to speak the truth. As a doctor, Grimes is close to the study of disease etiology. However, he’s a gastroenterologist, not a cardiologist or epidemiologist. This allows him to say whatever he wants about the cause of heart disease. He won’t be punished for heretical ideas.