Providing dietary guidance amidst inevitable change

Featured article in the Spring 2015 Issue of Nutrition Close-Up; written by Mitch Kanter, PhD

By now you are well aware that the Dietary Guidelines Advisory Committee has concluded its deliberations, and has submitted its recommendations to USDA and HHS regarding the 2015 Dietary Guidelines. A few issues addressed by the Committee that have provoked discussion include sustainability and the significant limits placed on added sugars and saturated fat-containing animal products in the diet. 

For some, the loosening of the reins on dietary cholesterol remains an area of contention. Doing what is perceived by many to be a 180 degree turn on more than 50 years of dietary guidance may seem like a sea-change to many. However in many cases, the preponderance of available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol.

This may be why a 2013 AHA/ACC Guideline on Lifestyle Management to Reduce Cardiovascular Risk states, in part, that “there is insufficient evidence to determine whether lowering dietary cholesterol reduces LDL-C.”  And it further suggests that adults who would benefit from lower LDL-C should hold saturated fat intake between 5% and 6% of calories; reduce the percent of caloric intake from saturated fat and from trans fat; and consume a dietary pattern emphasizing particular foods such as vegetables, fruits and whole grain. None of the advice put forth in these guidelines dealt with cholesterol-rich foods.

The lack of a relationship between dietary cholesterol and serum cholesterol may also explain why a number of developed and developing countries focus heart healthy diet advice on reductions in saturated fat and trans fat intake as opposed to reducing dietary cholesterol. Among the countries that do not recommend an upper limit for dietary cholesterol are Australia, the United Kingdom, Ireland, South Korea, India and New Zealand.  The European Society of Cardiology and other professional bodies likewise have issued guidelines that do not include upper limits on cholesterol intake. As two prominent British nutritionists recently wrote: “Most health and heart advisory bodies in the UK, Europe and elsewhere no longer set limits on the number of eggs people should eat, provided they are consumed as part of a healthy diet that is not high in saturated fatty acids.”

So, based purely on the science, it does appear that the DGAC’s recommendation to alter cholesterol guidance is warranted. This does not mean, however, that everyone in (or out) of the nutrition science community is ready to jump on board. Animal action groups, or groups and individuals who support a vegan lifestyle, have not been eager to accept the committee’s recommendation.  And some nutritionists have argued that by “taking the shackles” off of dietary cholesterol intake we may be sending the erroneous signal that folks can now eat other high-fat, high-calorie foods with impunity. This may well be a valid public health concern, and one that clinicians and researchers alike will need to keep an eye on should the committee’s recommendations be accepted by USDA/HHS.

With that in mind, it should be remembered that the DGAC’s recommendation to de-emphasize cholesterol as a nutrient of concern for overconsumption does not suggest that it can or should be consumed in excess, particularly when accompanied by high saturated fat, high-calorie fare. So when consuming cholesterol-containing foods like eggs or shell fish, it’s still important to be mindful of “the company” that they’re keeping. Few would argue that a breakfast consisting of eggs with whole grain toast, low fat yogurt/milk, and a cup of fruit, for example, is anything less than a heart-healthy meal.

Our understanding of the relationship between dietary cholesterol, serum cholesterol, and heart disease risk has changed dramatically in recent years with the publication of various up-to-date meta analyses, and other epidemiological and experimental studies. And it’s heartening to know that the DGAC apparently read many of these new studies, and altered recommendations accordingly. Nutrition science is not a static field. Things are changing constantly, and keeping up with the literature is important in order to make prudent dietary choices. Whether or not you agree with all of the recommendations put forth by the 2015 Guidelines Committee, it must be acknowledged that the panel did use available science as best it could to make the recommendations it did. In an ever-changing scientific environment, that’s probably the best that we could ask for.