Plant-based diets have the potential to address the issue of poor diet quality by offering crucial macronutrients, micronutrients, and fiber. In this article, we will explore the essential nutrients required for maintaining optimal health and examine how plant-based diets effectively fulfill these recommendations.

Abstract

The prevalence of poor diet quality is increasingly recognized as a significant contributor to deteriorating health and the rise of chronic diseases. This global challenge is compounded by a “double burden” scenario, characterized by undernutrition resulting from insufficient energy and/or nutrient intake, alongside poor nutrition stemming from excessive consumption of calorie-dense, nutrient-deficient foods. Plant-based diets offer a promising solution to address poor diet quality by providing vital macronutrients and micronutrients, along with the beneficial inclusion of intact fiber that aids in the regulation of food consumption and absorption. This paper critically examines the essential nutrients necessary for maintaining optimal health and evaluates the capacity of plant-based diets to effectively fulfill the recommended nutritional guidelines.

Key Points for Practitioners

• The dietary patterns commonly observed among adults in the United States are generally of poor quality, characterized by inadequate consumption of calcium, magnesium, potassium, iron, vitamins A, C, D, E, choline, and fiber, along with excessive intake of added sugars, saturated fat, and sodium.
• In contrast, whole food diets that are predominantly or entirely plant-based naturally provide higher amounts of the nutrients typically underconsumed while being lower in nutrients that are commonly overconsumed.
• To achieve a high-quality dietary pattern, it is advisable to prioritize plant foods and pay attention to specific important details. These include considering supplementation with vitamin B12 and vitamin D when sunlight exposure is inadequate, as well as incorporating sea vegetables and/or iodized salt into the diet.
• Adequate protein intake can be easily achieved by following a whole food, entirely plant-based diet.
• When patients express interest in adopting a whole food, plant-based diet of any kind, it is beneficial to provide them with educational and supportive resources.

Diet Quality in Context

The concept of diet quality encompasses the ability of a comprehensive dietary pattern to provide sufficient energy and all essential nutrients from food, facilitating growth, healing, physical activity, and optimal health at all life stages, as measured by standardized dietary metrics. However, a new multidimensional definition also considers factors such as nutrition, sociocultural aspects, food safety, and sensory features. It is widely acknowledged that a diet centered around minimally processed whole foods, while minimizing or avoiding refined foods with added sugars, fats, and salt, as well as processed animal products, is the healthiest dietary pattern for most individuals. Common components of diet quality metrics include vegetables, fruits, grains, roots, tubers, and specific nutrients like added sugar and saturated fat. Conversely, mixed dishes such as burgers, pizza, and salty or sweet snacks, containing added sugars, sodium, and saturated fats, are associated with adverse health outcomes.

Poor diet quality is a significant and preventable contributor to poor health and chronic diseases. Globally, we face a “double burden” of malnutrition, encompassing both inadequate intake of calories or nutrients (both macronutrients and micronutrients) and poor nutrition due to overconsumption. Modern malnutrition is characterized by excessive calorie consumption, along with the intake of sugar, fat, and salt, often leading to obesity, type 2 diabetes, cardiovascular diseases, and cancer. In the United States, poor diet quality is a major driver of chronic diseases, affecting six out of ten Americans. With improved living standards and increased food availability worldwide, the focus has shifted from obtaining sufficient energy to consuming a healthy diet for disease prevention within an environment of excess.

The overall dietary pattern has a profound impact on human health, disease development, and overall quality of life across all ages. Current food trends, marked by a Western-style diet consisting of animal products and processed foods, excessive calories, added sweeteners, and saturated fats, coupled with inadequate consumption of whole grains, legumes, fruits, and vegetables, contribute to the escalating rates of chronic conditions and obesity. Building food systems that promote diet quality have the potential to foster human health and address disease conditions. The influential 2020 EAT-Lancet Commission on Food, Planet, and Health from Harvard University emphasizes that “unhealthy diets pose a greater risk to morbidity and mortality than unsafe sex, and alcohol, drug, and tobacco use combined.” Therefore, public health initiatives, aligned with the U.N. Sustainable Development Goals, must address the dual challenge of malnutrition and excess. Lifestyle medicine, including nutritional prescriptions, holds promise in guiding individuals toward higher-quality dietary patterns.

Measuring Diet Quality

Assessment of diet quality is crucial for the development of effective strategies and public policies aimed at addressing malnutrition and achieving global nutrition safety. This is evident in the U.N. Sustainable Development Goals, which emphasize the importance of measuring diet quality using reliable dietary metrics that capture aspects such as quality, adequacy, and diversity. A recent systematic review identified nineteen validated dietary metrics that are widely used to address maternal and child health (MCH) and non-communicable diseases (NCD). The metrics varied, with MCH metrics focusing on key foods like grains, fruits, vegetables, dairy products, meat, and fish, while NCD metrics encompassed a more diverse range of foods and nutrients. Among these metrics, only four (Mediterranean Diet Score, Alternative Healthy Eating Index, Healthy Eating Index, and Dietary Approaches to Stop Hypertension) demonstrated convincing evidence of protective associations, particularly for all-cause mortality, cardiovascular diseases, type 2 diabetes, total cancer, and cancer mortality.

In the context of diet quality, several terms hold relevance:

• Adequacy: Ensuring sufficient consumption of specific foods or nutrients to maintain health.
• Moderation: Restricting intake to prevent adverse health effects and reducing the consumption of selected foods associated with increased disease risk.
• Dietary Reference Intakes (DRIs): A set of standards and recommendations by the National Academies of Sciences, Engineering, and Medicine (NASEM) that address adequacy and moderation. The DRIs include components such as Estimated Average Requirement (EAR), Recommended Dietary Allowance (RDA), Adequate Intake (AI), Tolerable Upper Intake Level (UL), and Chronic Disease Risk Reduction Level (CDRR).
• Undernutrition: Insufficient energy and nutrient intake leading to inadequate physical growth, weight loss, cognitive impairment, and increased susceptibility to infectious diseases and mortality. Malnutrition encompasses both undernutrition and overnutrition.
• Overnutrition: Excessive intake of macronutrients and micronutrients, often associated with poor diet quality and characterized by excessive calories, saturated fat, and sodium.
• Malnutrition: The definition of malnutrition remains ambiguous, but it traditionally refers to insufficient caloric or nutrient intake leading to physical growth issues, cognitive impairment, and increased risk of infectious diseases. In the context of chronic diseases, malnutrition also includes excess consumption of fat, sugar, salt, and calories. The World Health Organization has broadened the definition to encompass undernutrition, inadequate vitamin or mineral intake, overweight, obesity, and diet-related chronic diseases.
• Underconsumed and overconsumed nutrients: Nutrients or foods that are consumed insufficiently or excessively, respectively. Nutrients such as calcium, magnesium, potassium, iron, vitamins A, C, D, E, choline, and fiber are underconsumed, while added sugars, saturated fat, and sodium are overconsumed. Some of these nutrients are considered Nutrients of Public Health Concern due to their association with health risks. They are included on U.S. food labels.

Regarding children’s nutrition, although research on plant-based diets for children is limited, most studies suggest no detrimental effects and even indicate potential health benefits, such as lower risks of obesity, cardiovascular disease, and diabetes. Parents of vegetarian or vegan children should pay attention to critical nutrients like protein, iron, calcium, vitamins D and B12, and omega-3 fatty acids. Both vegetarian and omnivore children exhibit similar physical development, meeting protein and energy reference values. However, iron intake in both groups tends to be around 60-70% of the recommended intake. The Dietary Guidelines for Americans now recommend exclusive human milk for the first six months of life and human milk (not plant or cow’s milk) for the first 12 months for children under two years old.