1 Chapter 1: Introduction to Nutrition in Health and Disease
What is a Diet?
In everyday language, the word diet is often used to mean a specific and restrictive eating pattern aimed at weight loss or another precise health goal.
More commonly, in the field of nutrition science, diet simply refers to an individual’s nutrient intake habits. A diet can range from a highly regulated pattern, like a clinical or medicinal regimen, to something more unstructured, reflecting cultural or lifestyle patterns.
Some diets, such as the Mediterranean or DASH diets, are evidence-based, regulated, patterned diets designed to improve a person’s cardiovascular health or blood pressure (Estruch et al., 2018). Others, like low-carbohydrate diets – most often known as ketogenic or Atkins diets – and newly popular diets, such as intermittent fasting or carnivore diets, have anecdotal or clinical success for certain health conditions; however, these diets require additional long-term data and further research in controlled trials to assess their overall efficacy among larger populations.
In other words, a diet is not always one meticulous limiting food plan; it is better thought of as a lifestyle and overall pattern of food intake.
An optimal diet varies depending on individual needs, preferences, health status, and cultural background. Although there is no one-size-fits-all method, several patterns are universally advised by dieticians and medical specialists because of their overwhelming effectiveness over an extensive body of data.
What Are Nutrients?
The body needs nutrients, which are chemical substances, to carry out vital life processes. They can be found in all foods and have a variety of functions, including supplying energy, promoting growth and repair, regulating metabolism, and preventing disease. Foods have a mix of water, micronutrients (vitamins and minerals), macronutrients (proteins, fats, and carbohydrates), pigments, antioxidants, enzymes, and flavorings. These components work synergistically in the body.
Example
Metabolism: The Chemistry of Life
You may have heard of certain people having a “fast metabolism” or “slow metabolism”. Metabolism refers to the sum of all chemical processes that occur within living cells to maintain life. One of these processes includes how your body converts food into energy. The ability to convert food into energy at a faster rate at rest is colloquially known as a “fast metabolism.” The number of calories your body burns at rest to maintain basic functions is known as your basal metabolic rate (BMR) and will be discussed more extensively later in this textbook.
A healthy metabolism enables the body to produce energy effectively, repair damaged tissues, and maintain homeostasis.
Some of our most common chronic diseases, like obesity and type 2 diabetes, are often caused by disruptions in metabolic processes, such as insulin resistance or mitochondrial dysfunction.
Essential vs. Nonessential Nutrients
The body needs nutrients to metabolize and survive. Nutrients are categorized as either essential or nonessential based on the body’s ability to synthesize them.
- Essential nutrients cannot be made by the body, so they must be consumed through the diet because the body cannot produce them or produce enough to meet its needs. These include certain amino acids (such as lysine), fatty acids (such as omega-3), vitamins (such as vitamin D), and minerals (such as calcium).
- Nonessential nutrients can be made by the body, such as cholesterol or certain amino acids like alanine. There is simply no clearly defined requirement for them, unlike essential nutrients. However, the name nonessential does not mean they are unimportant—nonessential nutrients still play crucial roles in health.
The Relationship Between Nutrients and Long-Term Health
Nutrients play a critical role not only in daily functioning but also in the prevention and progression of disease. High-quality diets rich in fiber, healthy fats, lean proteins, and antioxidants (all things you will learn about later in this textbook) are associated with lower risks of cardiovascular disease, metabolic syndrome, cancers, and mental and emotional health.
Public health initiatives, such as Healthy People 2020 and Healthy People 2030, showcase the importance of dietary patterns in improving the health of Americans and the prevention of chronic diseases. These initiatives emphasize whole foods, increasing fiber, and reducing sugar and sodium, but they also highlight the social determinants of health, which have a significant secondary impact on Americans’ food choices.
Boiling Down the Basics of Nutrition
What are bad foods you can think of?
Making nutritional decisions can be made easier by adhering to a few simple rules. Most foods are comprised of a variety of nutrients, and some foods are more associated with disease prevention, while others are more associated with disease acceleration. There is no such thing as a “bad” food in isolation, and no single food is perfect. Quantity often determines health and disease outcomes. For instance, sugar-sweetened beverages, such as soda, do not provide many nutrients, and their consumption is associated with higher rates of diabetes and obesity. However, one isolated soda will not make or break a diet, though chronic consumption of soda can deprive the body of essential nutrients and provide an excess of calories and sugar – resulting in harmful biological processes that lead to disease and weight gain. Identifying foods that have higher ratios of fiber, antioxidants, vitamins, and minerals, and eating an assortment of those foods, makes it more likely that you will meet your nutritional requirements.
You often hear “anything in moderation”. What does moderation mean?
Moderation means avoiding excess, whether it be too much fat, sugar, sodium, or even over-supplementation. Excessive intake of certain vitamins, such as vitamin A, can actually be harmful and toxic. The goal of dietary balance should be sufficiency without extremes.
General nutrition guidelines include:
- consume nutrient dense foods
- limit empty calories
- don’t megadose any one food
- everything in moderation
- moderation does not mean gluttonous or reckless
- ○ Find what makes you feel best while being nutritionally rich
- no one size fits all
What is a Calorie?
Nutrition as an Evolving Science
Nutrition science is not static. A hundred years ago, scientists were just discovering vitamins and how to prevent diseases like scurvy and rickets. Today, we’re focused on preventing chronic diseases and improving quality of life across the lifespan.
Nutrition is a dynamic science and process. Our understanding will continue to evolve as technology advances and new research emerges. Personalized nutrition, nutrigenomics, and the gut microbiome are just a few areas where future research may provide a better understanding of nutrition science.
- What we know now is infinitely more than what we knew 100 years ago
- What we will know 100 years from now is infinitely more than what we know now
Media Attributions
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- Female microbiologist using microscope in laboratoty , examinating vegetables.