By Oscar E. Dimant
Peer Reviewed
Nutritional counseling is an integral part of helping patients live healthier lives, as research demonstrates the ability of proper nutrition to prevent disease and even treat and reverse chronic disease. This article provides an overview of evidence-based nutrition and clinical tips for counseling adult patients in a primary care setting.
It is useful to discuss nutrition in terms of specific foods and food groups, rather than macronutrients. For example, carbohydrates in the form of whole grains are extraordinarily healthful, but they are harmful when highly processed, so the term “carbohydrate” can be misleading.
Meats: Red meats are mammalian muscle meats, such as beef, pork, lamb, veal, and goat. Processed meats are those that have undergone a preservation process including salting, curing, smoking, or the addition of preservatives; examples include hot dogs, ham, pepperoni, deli meats, bacon, and sausage. In 2015 the World Health Organization classified processed meat as a Group 1 Carcinogen (the strongest level of evidence available), finding that processed meat causes colorectal cancer in a dose-response relationship. They classified unprocessed red meat as probably carcinogenic to humans (Group 2A level of evidence), since it is linked to colorectal, pancreatic, and prostate cancer, but without demonstration of causality. The mechanisms are still under investigation, but we know that processing and even just cooking red meat can produce carcinogens, and heme iron in the gastrointestinal tract mediates formation of carcinogenic chemicals and lipid oxidation products. 1,13
Poultry, fish, eggs, and dairy: There is mixed evidence on their healthfulness, but vegetarian diets without these foods have consistently demonstrated health benefits, including improved glycemic control, lipid profile, and weight loss, as well as a decreased risk of ischemic heart disease and cancer; 2,3 similar effects have held up in randomized clinical trials. 2,4
Grains: Whole grains such as oats, whole wheat, brown rice, and barley support healthy weight, cardiovascular health, and improved glycemic control and insulin homeostasis in healthy controls and patients with type 2 diabetes, while refined grains contribute to the risk of chronic disease. 5,6,7 Three servings of whole grains a day has also been demonstrated to decrease the risk of colorectal cancer by 17% and total cancer mortality by 15%. 14,15
Legumes: Beans, lentils, and peas are valuable sources of fiber and protein. Legumes have been shown to be the most important food group predictor of survival among older adults of different ethnicities, with a 7-8% reduction in mortality hazard for every 20-gram increase in legume intake. 17
Fruits and vegetables: These have been shown to support health in myriad ways and decrease the risk of many chronic diseases, including hypertension, coronary artery disease, and stroke, and are associated with a reduced risk of cancer and all-cause mortality.2,3,9,18
Nuts and seeds: These are valuable sources of protein and unsaturated fat, and have been shown to protect cardiovascular health and improve insulin homeostasis.2 Certain nuts and seeds, including flaxseed, walnuts, chia seeds, and hemp seeds are also excellent sources of omega-3 fatty acids. Nuts have demonstrated mortality benefits in a dose-response relationship, lowering all-cause mortality and mortality related to cancer, diabetes, cardiovascular, respiratory, and neurodegenerative diseases. Interestingly, although peanuts have been shown to decrease mortality, peanut butter does not demonstrate this effect. This may be due to the addition of trans-fats to many commercial peanut butter preparations. 16
Sugar: Added sugars contribute to the risk of chronic disease and should be limited or avoided. However, sugars found in whole produce are not of concern. Fruits are associated with a decreased risk of developing type 2 diabetes and a lower risk of death and major vascular complications in diabetic patients. It is important to emphasize that these benefits apply to whole fruits, while fruit juice actually carries increased health risks. 19,20
It is difficult to overeat with a whole-foods, plant-based diet because fiber, protein, and unsaturated fat work together to increase satiety. Fiber (found only in plants) decreases the calorie density of foods and fosters healthy gut bacterial patterns, both of which promote a healthy body weight.21,22 This aspect of dietary change can help motivate patients: rather than counting calories and restricting food, patients can eat until they are satisfied.2 Research demonstrates that vegan/vegetarian diets are often acceptable to and sustainable for patients, , and the internet is full of recipes (https://www.forksoverknives.com/recipes/, http://allrecipes.com/recipes/1988/everyday-cooking/vegetarian, www.vegweb.com) that can help patients cook with familiar tastes and try new styles.
In a balanced, plant-based diet, patients can expect to meet almost all of their nutritional requirements. Vitamin B12 is an exception: since it is made by bacteria and consumed through some animal products, vegans and vegetarians should use a supplement. Additionally, attention should be paid to calcium, vitamin D, iodine, and omega 3 fatty acids. A more in-depth discussion to help allay fears and plan a healthful diet can be found in the article Position of the Academy of Nutrition and Dietetics: Vegetarian Diets.23
When discussing nutrition, first assess the patient’s current dietary habits (for example, with a 24-hour dietary recall) and state of knowledge, provide education, ask the patient what changes they want to start, and support the goals and speed of change that the patient chooses. Food plays many roles in people’s lives and choosing what to eat is an emotional and social choice at least as much as it is a logical one. Plant-Based Diets: A Physician’s Guide provides a helpful guide for initiating and maintaining a dialogue with patients. 12
Multiple sources of support are available, including counseling with a registered dietitian, community cooking classes, online guides (eg https://share.kaiserpermanente.org/wp-content/uploads/2015/10/The-Plant-Based-Diet-booklet.pdf ), and even a free 21-day plant-based kickstart service ( http://www.pcrm.org/health/diets/kickstart/kickstart-programs) that emails patients tips and recipes (available in English, Spanish, and Chinese). Patients concerned about cost may benefit from becoming familiar with the variety of stores in their neighborhood, batch cooking and eating more at home, buying frozen fruits and vegetables, using local farmers’ markets, and buying in bulk, especially legumes, whole grains, and root vegetables. A good review of how to eat plant-based on a budget can be found at http://nutritionstudies.org/plant-based-on-a-budget/. Patients in New York City who receive SNAP benefits have access to HealthBucks, which provides $2 to spend on produce for every $5 spent at farmers markets using SNAP/EBT. Patients outside of New York can inquire about what programs may be available and clinicians can inquire as to how we can help create programs.
Finally, it is important to remember and remind patients that lasting change often happens slowly, and the foundation of sustainable health behavior change is the clinician-patient relationship and the willingness to continue talking about and making attempts toward change.
Oscar E. Dimant is a 3rd year medical student at NYU School of Medicine
Reviewed by Michelle McMacken, MD, Medicine, NYU Langone Health
Image courtesy of Wikimedia
References
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