16.2 Nutrition Defined

Nutrition is an evolving branch of science regarding food and beverages, their nutrients and other components, and overall eating patterns in relation to the body’s needs for metabolism, maintenance, growth, reproduction, health, and repair. Researchers continue to learn about how different foods and beverages, their components, and various eating patterns affect our bodies and minds, our health, and our disease risk; these things can serve as protective or risk factors. Individual studies about nutrition-related topics sometimes reveal conflicting results, which can be confusing, but the evidence-based nutrition recommendations referenced throughout this content are not based on an individual study or what’s currently most popular in the media. Rather, nutrition experts have carefully reviewed many studies over time and considered the quality of research methods, sample sizes, and other important factors before making—or modifying—recommendations.

Ensuring that our bodies get adequate fuel and function well isn’t just about how much we eat; what we eat matters, too—for both long-term health and short-term function and wellbeing. For example, certain nutrients can impact memory and overall cognition, which is something all students are relying on (Holloway et al., 2011; Spencer, Korosi, Layé, Shukitt-Hale, & Barrientos, 2017). Nutrition also influences immune response; consuming inadequate amounts of essential nutrients can leave one more vulnerable to getting sick (Karacabey & Ozdemir, 2012). In other words, fueling our bodies with adequate essential nutrients, not just enough food overall, impacts how we feel and function day-to-day, in addition to helping prevent chronic diseases (McCullough et al., 2002).

Essential Nutrients

Essential nutrients are necessary for the body to survive and function properly, but our bodies either don’t produce them or produce them in inadequate quantities, so we need to get them from food and beverages. The six essential nutrients are:

• Protein
• Carbohydrate
• Fat
• Water
• Vitamins
• Minerals

Essential nutrients can be divided into two categories: macronutrients and micronutrients. Macronutrients—protein, carbohydrate, and fat—supply energy in the form of calories and therefore fuel our bodies. Micronutrients—water, vitamins, and minerals—do not provide energy in the form of calories, but are, nonetheless, extremely important for our health and functioning. Macronutrients can’t be converted to energy without sufficient micronutrients.

The amount of an essential nutrient sufficient to meet the nutrient requirements among nearly all healthy people is referred to as its recommended dietary allowance or RDA. Instead of an RDA, some nutrients have what’s called an adequate intake or AI, which is the level assumed to ensure nutritional adequacy when enough evidence hasn’t been developed for an RDA. Generally, recommended amounts of each of the nutrients can vary depending on one’s unique life stage and life circumstances, which can include things like age, sex, pregnancy and lactation, the presence of food allergies or sensitivities, and injury, illness, or disease. Eating patterns related to individual values and preferences—veganism for example—can also be a factor in recommendations. For these reasons, we don’t outline specific RDAs or AIs of each of the nutrients for all individuals. Rather, we cover the basics of what constitutes nutritious eating and provide some general guidelines and practices that can help foster optimal nutrition, physical and mental functioning, and health. In other words, the focus is more on what than how much. Also, when we refer to food, nutrition, and eating patterns, know that we are talking about both food and beverages, which may be whole or processed. Foods direct from nature or close to their natural state are considered whole foods, while processed food is any food that has been altered by a food manufacturer. Processed foods and beverages can range from minimally processed to highly or heavily processed.