Percentage of Fat in the Diet
Here’s something I’ve been mentioning in my talks lately. A 2000 study measured the percentage of calories as fat in the diet as well as cholesterol levels in a subset of EPIC-Oxford vegan and non-vegan men. Here is what they found:
|blood cholesterol (mg/dl)||191||158|
|% saturated fat||12%||5%|
|total fat (g)||93||64|
|*Cholesterol intake by vegans likely due to using foods that contained small amounts of animal products in calculating the nutrient composition of foods. In other words, using bread made with animal products versus vegan bread in the nutrient calculations. Also possible that some vegan participants were not 100% vegan.|
Vegans ate 30% of their calories as fat compared to 34% for meat-eaters. Not a huge difference and many people would be horrified at such a high fat intake on behalf of the vegans. Yet, their cholesterol levels were well below what is commonly considered the danger zone.
What accounts for this? The vegans’ much lower intake of saturated fat probably explains a lot. But the vegans’ 20% fewer calories also probably accounts for much of their lower cholesterol levels. Addendum 1/27/12: Additionally, higher fiber intake and zero or near-zero cholesterol intake all likely contribute to the vegans’ lower cholesterol levels. Clarification 1/30/12: People who exercise a lot can eat more calories without cholesterol levels increasing as long as they are not eating so much that they gain body fat (thanks, Ginny).
Some people might point out that ideal cholesterol levels are actually less than 150 mg/dl, so 158 mg/dl is too high. While many clinical trials in people with heart disease (and normally on cholesterol-lowering medication) show a benefit to getting levels below 150 mg/dl, I have not seen evidence that this is ideal, or even desirable in people without diagnosed heart disease or normally high cholesterol. Instead, the observational studies I’ve seen measuring cholesterol levels and mortality have not shown a benefit from cholesterol levels less than 160 mg/dl.
I would not completely rule out the idea that studies have not shown reduced mortality in people with cholesterol levels less than 160 mg/dl because they have not included enough people with cholesterol levels that low and who do not have such low levels due to undiagnosed disease. But “not completely ruling out something” is a far cry from saying there is good evidence that it is true.
The reason I think this is particularly important is anecdotal evidence that people on long-term, low-fat diets can find them hard to stick with. I know there are some exceptions – people who find them easy to stick with, but I sense that there are more who find it difficult. When people crave meat, they tend to think they are craving the protein. But meat is also about 50% fat on average and it would not surprise me if such people are often craving fat as much or more than protein. Eating a diet closer to 30% fat might prevent such cravings.
Yes, lots of qualifiers above that I’m not 100% certain of everything I’m saying. But I think there is enough evidence that I should share it with readers rather than just keeping it to myself until “further studies” are done.
Allen NE, Appleby PN, Davey GK, Key TJ. Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men. Br J Cancer. 2000 Jul;83(1):95-7. Link