Providing Effective Nutrition Advice to Patients

Integrating Evidence-Based Medicine, Common Sense, and Social Activism

Robert Baron, MD

Few topics in medical practice receive more attention in the lay media than nutrition. Each week brings new information about the advantages and disadvantages of specific diets, foods, and nutrients. Patients are confused and physicians are ill prepared to provide definitive answers. 

At the same time, patients and physicians are fully aware that what we eat has a major impact on our risk of developing a long list of chronic illnesses. And as physicians, all of us should be aware that changes in diet provide a powerful potential tool for management of these same illnesses.

The question is, what level of evidence is needed in order to provide patients with sensible nutrition advice? The complexity of nutritional science has made it difficult to design and implement definitive randomized trials. On the other hand, observational studies have often provided misleading information. We are forced to understand the strengths and weaknesses of the evidence that we have and combine it with a healthy dose of biologic common sense.

What do we know? Most convincingly, we know that we eat too many calories. The increase in overweight and obesity in the United States and a growing list of other nations clearly provides no identifiable health benefit (with the exception of increased bone mineral density). In fact, the United States is poised to reverse beneficial health trends for the first time in history. Debating the ideal body mass index for optimal health, the exact impact of obesity on mortality, and whether obesity is a greater threat to health than tobacco are all distractions from the basic point: There is no health advantage to being obese.  

We know that we are not active enough. All lines of evidence support the concept that decreased physical activity is associated with weight gain and that increased physical fitness (at any body weight) improves health outcomes. 

We know that we do not eat enough plant foods. Vegetables and fruits should be the backbone of every diet. Current dietary guidelines recommend nine servings per day for adults who require 2,000 calories per day.

Finally, we know that we eat way too much out of bags, boxes, and cans. High-calorie snack foods, convenience foods, and beverages are directly related to our increased weight and to our reduced vegetable and fruit consumption.

As Marion Nestle writes in What to Eat (North Point Press, 2006), the basic principles of a good diet can be summarized in fifteen words: eat less, move more, eat lots of fruits and vegetables, go easy on junk foods.

Manipulating Macronutrients

A substantial amount of recent nutritional science has been devoted to defining the optimal balance of macronutrients (fat, carbohydrates, and protein) in the diet. Efforts over the last several decades to demonstrate substantial health advantages of a low-fat diet have been largely negative. Reducing fat without reducing total calories has little direct impact on health outcomes. For example, the recent Women’s Health Initiative clinical trial of low-fat diets showed no improvement in weight, breast cancer, colon cancer, any and all other cancers, cardiovascular disease, or any and all causes of death. Similarly, studies evaluating carbohydrate restriction, particularly for weight loss, have also showed no clear advantages over more traditional “balanced” diets. 

More recent studies have focused on Mediterranean-style diets, emphasizing the role of “good fats and good carbs” rather than a restriction of either. The evidence supporting this approach is as strong as any. The bottom line, however, is this: Total calories trump macronutrient composition. For most clinical circumstances, e.g., for health promotion, disease prevention, and treatment of most chronic illnesses, calorie restriction (with a concurrent increase in physical fitness) will have greater impact on health outcomes than changes in macronutrient composition.

Supplementing Micronutrients

Few areas of nutrition have been subject to more study, including a large number of excellent randomized trials, than micronutrient (vitamin and mineral) supplementation. Observational studies have long suggested that individuals who consume greater amounts of a variety of vitamins and minerals (particularly those with antioxidant activity and those involved in homocysteine metabolism) had improved health outcomes. Dozens of randomized trials, however, have convincingly demonstrated the opposite. For example, no improvement in clinical outcomes can be identified from supplementation with antioxidant supplements or with a variety of B-vitamin supplements. This literature should provide future caution for those drawing premature conclusions from observational studies of diet and nutrition. 

What has been established is that vitamin and mineral supplements can prevent vitamin and mineral deficiencies. Patients with inadequate vitamin and mineral intakes should take simple multivitamin and mineral supplements. For example, individuals with inadequate dietary folate intake need folate supplementation during their reproductive years. Similarly, those with inadequate dietary calcium intake will likely benefit from calcium supplements during times of bone development. Providing levels of micronutrients greater than those needed for adequacy is not only unproven to be effective, but in many cases is proven to be ineffective.

Making Dietary and Physical Activity Changes

Unfortunately, knowing what to recommend to patients is only one aspect of the battle for good nutrition and physical fitness. Powerful commercial influences in both the food industry and those industries that effect physical activity make adhering to recommended behaviors extremely difficult. Patients must make substantial efforts just to maintain their current weight and level of fitness. Making changes that lead to weight reduction and improved fitness require near-heroic measures.

Randomized trials, however, demonstrate that both eating and exercise behavior can be changed. Although the mean impact is often modest, approximately one-quarter of patients demonstrate more significant changes. The National Weight Control Registry suggests that such changes can be maintained for the long term. Patients who are able to lose weight and keep it off continue to eat low-calorie diets (approximately 1,400 calories per day), exercise moderately for approximately one hour per day, and monitor their weight regularly.

Physicians must become skilled in teaching behavior-change techniques to patients who are ready to make changes. Useful skills include goal-setting, self-monitoring, stimulus control, and cognitive skills. Working closely with dieticians, psychologists, and other skilled professionals is essential. Studies that have most convincingly achieved behavior change, such as the Diabetes Prevention Program, have used very intensive interventions including multiple visits with nonphysician providers.

But physicians will also need to become activists to change our food and exercise environment. Radical changes in how food is produced, transported, sold, and purchased, and how our time is spent in transportation and at school, work, and leisure activities will be necessary to achieve the nutrition and physical activity outcomes that we desire.

Robert B. Baron MD, MS is a Professor of Medicine, Associate Dean for Graduate and Continuing Medical Education, and Vice Division Chief of the Division of General Internal Medicine at the University of California San Francisco (UCSF). A graduate of Princeton University (1971), Dr. Baron received a Masters Degree in Nutrition from the University of Wisconsin, Madison (1974) and his M.D. Degree from UCSF (1978). He did his residency training in UCSF's Primary Care Internal Medicine Residency Program.  
 
A member of the UCSF faculty since 1981, Dr. Baron directed the UCSF Primary Care Internal Medicine Residency from 1989 until 2006, training over 200 residents for primary care and general internal medicine careers.  Over the last 20 years, Dr. Baron has developed UCSF's extensive program in continuing medical education in primary care and currently chairs 7 CME courses each year.  In 2000, he became Associate Dean for Continuing Medical Education at UCSF and now leads UCSF's program of over 150 CME activities per year.  In 2006 he also assumed the role of Associate Dean for Graduate Medical Education and Designated Institutional Official, overseeing over 100 residency and fellowship programs.  Dr. Baron also founded and directs the UCSF Osher Lifelong Learning Institute, a year-round community education program.
 
A practicing internist, he has been recognized as one of "America's Top Doctors" and as one of the "Outstanding Primary Care Physicians in the U.S."  In addition to his practice in primary care, he maintains a special interest in nutrition and management of obesity. He founded and continues to direct the UCSF Weight Management Program.  Dr. Baron has received numerous teaching awards including UCSF’s Academic Senate "Distinguished Teacher Award" and the California Society of General Internal Medicine's "Clinician Teacher of the Year Award".  He focuses much of his scholarship on obesity and related topics in nutrition, in preventive medicine topics including hypertension and lipid management, and in issues in graduate and continuing medical education.