Experts buzzing about the scientific report of the dietary guidelines advisory committee released in mid-June certainly had a qualm here and there about the panel's tentative recommendations. But on the whole, a roundup of expert opinion gathered by The Times' Health section suggested there are some points of consensus about how -- and what -- to eat to get and stay healthy.
Proponents of a very low-carbohydrate diet such as that championed by Dr. Robert Atkins, however, found a lot to be steamed about as they read the report. The panel seemed to diss the low-carb lifestyle and its prospects for helping American adults shed excess weight.
Dr. Stephen Phinney, co-author of "The New Atkins for a New You," predictably took issue with the scientific advisory panel's assertion that "there is some evidence that [diets less than 45% of calories from carbohydrate] may be less safe."
That claim only works, says Dr. Phinney, if one is highly selective in the data one chooses to consider.
"Yes, in some -- but certainly not all -- studies, the Atkins diet raises total and maybe LDL cholesterol levels," Phinney acknowledges. But over the past two decades, thinking on cholesterol has changed. "That might have been worrisome" back when cholesterol was just a blunt instrument, a single number, says Dr. Phinney. "But now we know that the Atkins diet raises HDL (i.e., "good') cholesterol, which helps explain why the total cholesterol can go up without increasing risk."
Add to this what Phinney calls "the excellent evidence that carbohydrate restriction changes LDL cholesterol from the bad 'small dense' form to the lower-risk larger particles" -- a shift that represents a major reduction in risk, says Phinney. "But that is completely missed if one just uses the old way of measuring total LDL cholesterol." Finally, Phinney says, in most studies where it was measured, when people actually follow the Atkins diet, their level of inflammation -- which many believe is a predictor of heart disease risk -- goes down.
"A great deal of recent data that the Atkins diet may actually be more safe," says Phinney.
Phinney also objected to what he called the "continued demonization of saturated fats by the committee." He cites a recent journal article that makes the case there is no evidence to support the widespread belief that the consumption of saturated fat negatively affects heart health or overall mortality.
For people who follow the Atkins diet -- even those who eat more dietary saturated fat when they do -- blood levels of saturated fats go down, says Phinney. This apparent paradox, he adds, is due to a combination of the body adapting to a low-carb diet by rapidly burning saturated fats as fuel, plus a sharp reduction in the liver's production of saturated fats from dietary carbohydrates.
The dietary guidelines advisory committee, however, may have discounted evidence for these effects because published studies providing such data are relatively new.
"Frankly, I agree there might be concerns about combining a heavy intake of saturated fats along with lots of sugar and refined carbohydrate," Phinney says. "This combination (think double bacon cheeseburger plus supersized soda) is a diabolical combination designed to dramatically raise the saturated fat levels in your blood triglycerides.
"But when one removes the refined carbs and sugars, eats the 'foundation vegetables,' moderate protein, and healthy fats as described in our book, blood levels of saturated fats plummet, particularly in people with high risk conditions associated with insulin resistance (such as metabolic syndrome and Type 2 diabetes)."
-- Melissa Healy