The Science and Scope of Nutrition Jamie Pope, Steven Nizielski, and Alison McCook NUTRITION for a Changing World FIRST EDITION Chapter 1 The Science and Scope of Nutrition Exploring the Science of Nutrition © 2016 by W. H. Freeman and Company & Scientific American

Chapter 1 Objectives Define the scope and science of nutrition Explain the connection between nutrition and chronic disease Define and identify the major macronutrients and micronutrients Summarize the purpose of the dietary reference intake (DRI) values Distinguish between the different types of DRI values and what each represents Understand/explain the basis of the scientific method and how it is used in nutrition research Describe the three types of experimental design and the primary advantages of each Describe reliable sources of nutrition information

Science of Nutrition Are we not only what we eat but also what our mother’s ate? How can we eat to optimize our health? In the picture is a boy from the Dutch Hunger Winter period between October 1944 and May 1945. Later a research team at Columbia University looked at 300,000 nineteen-year-old men born around the time of the famine and found that men whose mothers were in the first months of their pregnancy during the famine were more likely to be obese than those whose mothers were in the last months of their pregnancy. Later research in the 1980s by David Barker, MD, PhD, found that babies with low birth weight were more likely to develop heart disease later in life. This has led to the “developmental origins hypothesis” that states certain diseases originate from conditions in pregnancy and infancy.

Science of Nutrition

Nutrition and Disease Risk Discuss how research and the science of nutrition have provided evidence that what we eat affects our health and risk of disease.

Food Provides Nutrients Chemical substances that provide nourishment essential for growth and the maintenance of proper body functioning Essential nutrients Cannot be made or made in sufficient amounts to meet the body’s needs

Nutrients Classes of nutrients Carbohydrates Proteins Fats (lipids) Vitamins Minerals Water

Energy Kilocalories = measurement of energy in food Kilocalorie (kcal) = 1,000 calories Calorie = kcal = 1,000 calories Carbohydrates, proteins, fats, and alcohol provide energy

Macronutrients Macronutrients are required in large amounts in the body. “Lipid” is the chemical term for fats. All macronutrients but water provide energy. Alcohol is not a nutrient but does provide energy, about 7 kcal/g. Carbohydrates, lipids, and proteins are organic molecules containing carbon and made in plants or animals.

Micronutrients Vitamins Minerals [Insert Infographic 1.4] Micronutrients are required in small amount in the body and are not a source of energy. Vitamins are organic substances made by plants and animals. Minerals are individual elements – seen on the periodic table from chemistry.

From Food to Nutrients in Our Body Digestion Extracts macronutrients, micronutrients, and phytochemicals from food Absorption Puts nutrients into our body Digestion breaks food down, extracting macronutrients and micronutrients as well as other things, like the phytochemicals seen in these blueberries. The color of blueberries comes from a phytochemical (plant chemical) called anthocyanin, which is a pigment that imparts colors ranging from blue to red. Many plant foods contain phytochemicals that we are just learning may potentially playing important roles in disease prevention. There are thousands of these phytochemicals in plant foods. [Insert picture of blueberry]

Malnutrition Undernutrition Overnutrition Nutrient deficiency Obesity Malnutrition is a state of inadequate or unbalanced nutrition. Undernutrition can be a lack of overall food or a lack of a specific nutrient, which equals nutrient deficiency. Obesity is caused by an overconsumption of foods high in fats (especially solid fats, such as animal fats), sugars, and sodium, which increases progression of chronic diseases such as heart disease, stroke, diabetes, cancer, and Alzheimer’s disease. Diet plays a role in prevention, risk, progression, and treatment of nearly every chronic disease. The typical Western diet consists of foods high in calories, fats, sugars, and sodium, but it is low in foods such as fruits, vegetables, and fish, leading to inadequate intake of nutrients that reduce the risk of chronic disease, such as fiber, potassium, calcium, and vitamin D.

Dietary Reference Intakes (DRI) Estimated average requirements (EAR) Recommended dietary allowances (RDA) Adequate intake (AI) Tolerable upper intake levels (UL) Nutrient Intake Recommendations DRIs include four values for nutrient intakes: 1) EAR: This is the average amount of a nutrient needed by sex and age group. This is an intake that meets the needs of 50 percent of individuals within that group. 2) RDA: This is EAR plus a safety factor set to meet or exceed the requirements of nearly all (98 percent) healthy individuals. The nutrient requirements for most people is less than their RDA for that nutrient, as it is padded to meet the needs of almost all healthy people. 3) AI: This is based on research or observation of the amount of the nutrient individuals typically need to be healthy. It is used when there is insufficient evidence to generate an EAR. 4) UL: This is the highest amount of a specific nutrient that most people can consume daily without causing any harm. As more research/evidence becomes available, DRIs are revised and modified. DRIs are set for macronutrients, micronutrients, electrolytes, and water.

Nutrient Intake Recommendations DRIs include four values for nutrient intakes: 1) EAR: This is the average amount of a nutrient needed by sex and age group. This is an intake that meets the needs of 50 percent of individuals within that group. 2) RDA: This is EAR plus a safety factor set to meet or exceed the requirements of nearly all (98 percent) healthy individuals. The nutrient requirements for most people is less than their RDA for that nutrient, as it is padded to meet the needs of almost all healthy people. 3) AI: This is based on research or observation of the amount of the nutrient individuals typically need to be healthy. It is used when there is insufficient evidence to generate an EAR. 4) UL: This is the highest amount of a specific nutrient that most people can consume daily without causing any harm. As more research/evidence becomes available, DRIs are revised and modified. DRIs are set for macronutrients, micronutrients, electrolytes, and water.

EAR Number of Individuals Minimum Nutrient Requirements

EAR Number of Individuals 50% Population Minimum Nutrient Requirements

RDA Number of Individuals 98% Population Minimum Nutrient Requirement

Dietary Reference Intakes [Insert infographic 1.6]

Dietary Reference Intakes The DRIs help to determine if the intake of a group, population, or community is in the adequate and safe range or if there is risk of inadequacy or toxicity (both of which lead to malnutrition). The DRIs vary for different groups of people (children, adults, men and women, elderly, and women who are pregnant or nursing), so there are different values given for each group.

Nutrition Science in Action Robert Waterland, PhD Hypothesis Experiment Control group Experimental/treatment group Results Published Peer-reviewed journal Dr. Waterland noted that the diet in pregnant mice changed the coat color and health of babies. This observation led him to ask a question as a testable hypothesis about whether supplementing the diet of pregnant mice would increase the frequency of the healthier brown-coated offspring. Waterland designed and conducted an experiment to test the hypothesis. He randomized mice into two groups: a control group of pregnant mice on a healthy diet without supplements and a treatment/experimental group with a healthy diet plus B-vitamin supplements. He made sure the only difference between the groups was the supplements so that he would know that could be the only cause of any differences. His results led him to accept his hypothesis, as the experimental mice had more brown-coated offspring, which are less obese and have less cancer. DNA analysis showed that the dietary supplements affected the DNA expression or epigenetics. He published his work in a peer-reviewed journal.

The Scientific Method Research design and consistency across studies are important determinants of the quality, reliability, and applicability of study findings. Nutrition studies may be retrospective or prospective in nature.

Types of Nutrition Studies Epidemiological studies make observations of populations, while experimental studies explore research questions over time. We often observe an effect in a epidemiologic study, which can then be confirmed in a reflective/correlational data study. The effect is then tested for in experimental model systems. This provides the preliminary data and support to justify the cost and time necessary to conduct randomized controlled trials (RCT) in order to rule out placebo effect and apply the results to the human population with strong evidence to support it.

Credible Sources of Nutrition Information Lots of information available Internet, television, magazines, media Are they credible?

Credible Sources of Nutrition Information Evidence-based information uses Scientific method Each study is a piece of evidence Multiple peer-reviewed publications Repeated consistent results equals stronger evidence Evidence-based information means that the information has been studied several times. The information has been repeated, with similar results found in multiple studies published in peer-reviewed publications, demonstrating it was not likely found by coincidence and is more likely a cause-and-effect relationship. Each peer-reviewed publication demonstrating the same thing makes the evidence stronger and more likely to be credible. One study does not prove anything; it just gives support to an idea.

Credible Sources of Nutrition Information Experts in the field Registered dietitian nutritionists (RD or RDN) Advanced degree in nutrition or a related field Government agency Research institution Nutrition information is supported by a group of experts in the field, such as registered dietitian nutritionists, those with advanced degrees in nutrition or nutritional biochemistry, government agencies, or research institutions. This support makes it more likely to be credible. Registered dietitian and registered dietitian nutritionist are legally defined terms for someone having completed an accredited education program and having passed an exam demonstrating knowledge and training in foods, nutrition, and dietetics.

Credible Sources of Nutrition Information Web sites, magazines, television, media Be wary of Sources trying to sell a product Sources using dramatic or scare tactics Sites ending in “.com” Turn to Sources referencing peer-reviewed, published data and experts in the field Sites ending in “.gov,” “.edu,” or “.org” When using magazines, television or media determine the source of the information and if it is a credible source. Then you may need to turn to the original source as often only pieces of the information are provided in the final story. Be wary of Websites ending in “.com” (which might be selling a product related to the nutrition advice), and turn to sites that end in “.gov,” “.edu,” or “.org” (which are managed by health-care professionals).

Healthy People 2020 Government-sponsored initiative Based on scientific evidence Ten-year objectives to improve the health of all Americans Consume a variety of nutrient-dense foods Emphasize whole grains, fruits, vegetables, low-fat dairy products, lean meats, and other sources of protein Eat only as many calories as needed Limit intake of saturated fats, trans fats, cholesterol, added sugars, sodium (salt), and alcohol www.healthypeople.gov

Assessing the North American Diet National Health and Nutrition Examination Survey (NHANES) Assesses the food and nutrient consumption of Americans How do we know what American’s eat? The US government monitors the health of Americans through NHANES. It shows that we are eating too much solid fats and added sugar and not enough red, orange, and deep green vegetables. We are not meeting the objectives of Healthy People 2020 and have a poor diet that is affecting the health of our country.

Summary Nutrition science is an interdisciplinary field that studies dietary intake and behavior, as well as the nutrients and constituents in food, their use in the body, and their influence on human health Nutrients are chemical substances obtained from food that are required for normal growth, development, reproduction, and tissue maintenance and repair The six classes of nutrients include macronutrients (carbohydrates, proteins, fats, and water) and micronutrients (vitamins and minerals) Malnutrition can be the consequence of undernutrition, which may result in nutrient deficiencies, or overnutrition

Summary (Cont’d) Dietary reference intakes (DRI) provide quantitative estimates of recommended nutrient intake for individuals on the basis of gender, age, and life stage DRI encompasses estimated average requirements (EAR), recommended dietary allowances (RDA), adequate intake (AI), and tolerable upper intake levels (UL) Nutrition research employs the scientific method Registered dietitian (RD) or registered dietitian nutritionist (RDN) are standard legal terms for someone having extensive knowledge and training in foods, nutrition, and dietetics

Summary (Cont’d) Healthy People 2020 is a government-sponsored initiative that provides science-based, 10-year national objectives for improving the health of all Americans The health and diets of Americans are monitored through government surveys like the National Health and Nutrition Examination Survey (NHANES)