On ADA’s type 2 message board, someone posted the comment, “I do know that 85 percent of your cholesterol levels are determined not by your diet but by heredity, so while diet can make a difference, the effect on cholesterol is limited.”

How would you reply to that? How might I motivate someone asking for help with cholesterol?

Thomas Muffaletto
New York, N.Y.

Craig Williams, PharmD, responds: The contribution of diet versus genetics in any given individual’s cholesterol levels is something we can’t determine with any real accuracy. It is generally true that genetics is more important. However, there is an important interaction between the two, and the importance of diet should never be discounted.

While this is true even in patients who do not become overweight, it is particularly evident in patients who do become overweight or obese. Regardless of the content of the diet, when too many calories result in extra unwanted pounds, it can have the profoundly negative effects of both increasing total cholesterol and lowering good cholesterol (HDL).

In patients who do not become overweight, having an unhealthy diet (high in saturated fats and low in soluble and insoluble fiber) still has negative effects, particularly on increasing the bad cholesterol (LDL). The extent to which improving diet can improve cholesterol varies, but effects can be very significant.

The Ornish diet, which stresses a lot of fruit and vegetables with very low fat intake, has been found to be able to lower cholesterol by nearly 50 percent. With the more common changes in diet that we see in clinical practice, reductions of 10 to 20 percent are more common. Still, remember that greater changes can produce greater benefits.