Plant-Based Diets: A Physician’s Guide

Abstract

Because of the ever-increasing body of evidence in support of the health advantages of plant-based nutrition, there is a need for guidance on implementing its practice. This article provides physicians and other health care practitioners an overview of the myriad benefits of a plant-based diet as well as details on how best to achieve a well-balanced, nutrient-dense meal plan. It also defines notable nutrient sources, describes how to get started, and offers suggestions on how health care practitioners can encourage their patients to achieve goals, adhere to the plan, and experience success.

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Summary of Health Benefits

Plant-based nutrition has exploded in popularity, and many advantages have been well documented over the past several decades. Not only is there a broad expansion of the research database supporting the myriad benefits of plant-based diets, but also health care practitioners are seeing awe-inspiring results with their patients across multiple unique subspecialties. Plant-based diets have been associated with lowering overall and ischemic heart disease mortality; supporting sustainable weight management; reducing medication needs; lowering the risk for most chronic diseases; decreasing the incidence and severity of high-risk conditions, including obesity, hypertension, hyperlipidemia, and hyperglycemia; and even possibly reversing advanced coronary artery disease and type 2 diabetes.

The reason for these outcomes is two-fold. First, there are inherent benefits to eating a wide variety of health-promoting plants. Second, there is additional benefit from crowding out—and thereby avoiding—the injurious constituents found in animal products, including the following:

Saturated fats: Saturated fats are a group of fatty acids found primarily in animal products (but also in the plant kingdom—mostly in tropical oils, such as coconut and palm) that are well established in the literature as promoting cardiovascular disease (CVD). The American Heart Association lowered its recommendations for a heart-healthy diet to include no more than 5% to 6% of total calories from saturated fat, which is just the amount found naturally in a vegan diet (one consisting of no animal products).

Dietary cholesterol: Human bodies produce enough cholesterol for adequate functioning. Although evidence suggests that dietary cholesterol may only be a minor player in elevated serum cholesterol levels, high intakes are linked to increased susceptibility to low-density lipoprotein oxidation, both of which are associated with the promotion of CVD. Dietary cholesterol is found almost exclusively in animal products.

Antibiotics: The vast majority (70% to 80%) of antibiotics used in the US are given to healthy livestock animals to avoid infections inherent in the types of environments in which they are kept. This is, therefore, the number one contributor to the increasingly virulent antibiotic-resistant infections of the type that sickened 2 million and killed 23,000 Americans in 2013.

Insulin-like growth factor-1: Insulin-like growth factor-1 is a hormone naturally found in animals, including humans. This hormone promotes growth. When insulin-like growth factor-1 is consumed, not only is the added exogenous dose itself taken in, but because the amino acid profile typical of animal protein stimulates the body’s production of insulin-like growth factor, more is generated endogenously. Fostering growth as a full-grown adult can promote cancer proliferation.

Heme iron: Although heme iron, found in animal products, is absorbed at a higher rate than nonheme iron, found in plant-based and fortified foods, absorption of nonheme iron can be increased by pairing plant-based protein sources with foods high in vitamin C. Additionally, research suggests that excess iron is pro-oxidative and may increase colorectal cancer risk and promote atherosclerosis and reduced insulin sensitivity.

Chemical contaminants formed from high temperature cooking of cooked animal products: When flesh is cooked, compounds called polycyclic aromatic hydrocarbons, heterocyclic amines, and advanced glycation end products are formed. These compounds are carcinogenic, pro-inflammatory, prooxidative, and contributive to chronic disease.

Carnitine: Carnitine, found primarily in meat, may be converted in the body by the gut bacteria to produce trimethylamine N-oxide (TMAO). High levels of trimethylamine n-oxide are associated with inflammation, atherosclerosis, heart attack, stroke, and death.

N-Glycolylneuraminic acid (Neu5Gc): This compound is found in meat and promotes chronic inflammation.

Advantages of Plant Foods

On the other hand, there are infinite advantages to the vast array of nutrients found in plant foods. Phytochemicals and fibers are the two categories of nutrients that are possibly the most health promoting and disease fighting. Plants are the only source of these nutrients; they are completely absent in animals. Plants contain thousands of phytochemicals, such as carotenoids, glucosinolates, and flavonoids, which perform a multitude of beneficial functions, including:

Antioxidation, neutralizing free radicals

Anti-inflammation

Cancer activity reduction via several mechanisms, including inhibiting tumor growth, detoxifying carcinogens, retarding cell growth, and preventing cancer formation

Immunity enhancement

Protection against certain diseases, such as osteoporosis, some cancers, CVD, macular degeneration, and cataracts

Optimization of serum cholesterol.

Fibers found in whole plant foods powerfully support the gastrointestinal, cardiovascular, and immune systems through multiple mechanisms. Yet more than 90% of adults and children in the US do not get the minimum recommended dietary fiber.42

Thus, it can be advantageous for physicians to recommend and support plant-based eating to achieve optimal health outcomes and possibly minimize the need for procedures, medications, and other treatments. Aiming for lifestyle changes as primary prevention has been estimated to save upwards of 70% to 80% of health care costs because 75% of health care spending in the US goes to treat people with chronic conditions.43 Offering this option and guiding patients through the logistics and their concerns about plant-based eating is a viable first line of therapy in the clinical setting. This article will delineate how best to achieve a well-balanced, nutrient-dense meal plan, define notable nutrient sources, describe how to get started, and offer suggestions on how physicians can encourage and work with their patients who are interested to maintain adherence and enjoy success.

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