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1C H A P T E R

The Role of Nutrition The Role of Nutrition in Our Healthin Our Health

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What Is Nutrition?

Nutrition: the study of food, including How food nourishes our bodies How food influences our health

Nutrition is a relatively new discipline of science.

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Why Is Nutrition Important?

Nutrition contributes to wellness.

Wellness: the absence of disease Physical, emotional, and spiritual health

Critical components of wellness Nutrition Physical activity

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Why Is Nutrition Important?

Nutrition encompasses the following aspects of food Consumption Digestion Absorption Metabolism Storage Excretion

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Why Is Nutrition Important?

Nutrition also studies these aspects of food Psychological Food safety Global food supply Cultural

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Why Is Nutrition Important?

Figure 1.1

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Why Is Nutrition Important?

Nutrition can prevent disease. Nutrient deficiency diseases:

scurvy, goiter, rickets Diseases influenced by nutrition:

chronic diseases such as heart disease Diseases in which nutrition plays a role:

osteoarthritis, osteoporosis

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Why Is Nutrition Important?

Obesity is a growing

problem.

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Why is Nutrition Important?

Nutrition is so important that it has become a national goal.

Goals of Healthy People 20101. Increase quality and years of healthy life

2. Eliminate health disparities

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What Are Nutrients?

Nutrients: the chemicals in foods that are critical to human growth and function.

carbohydrates vitamins

fats and oils minerals

proteins water

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What Are Nutrients?

Macronutrients: nutrients required in relatively large amounts (g or Kg).

Provide energy Carbohydrates, fats and oils, proteins

Micronutrients: nutrients required in smaller amounts (g or mg).

Vitamins and minerals

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Energy from Nutrients

We measure energy in kilocalories (kcal).

Kilocalorie: amount of energy required to raise the temperature of 1g of water by 1°C.

On food labels, “calorie” actually refers to kilocalories.

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Carbohydrates

Primary source of fuel for the body, especially for the brain

Provide 4 kcal per gram Carbohydrates are found in grains (wheat, rice),

vegetables, fruits, and legumes

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Fats and Oils

Are composed of lipids, molecules that are insoluble in water

Provide 9 kcal per gram Are an important energy source during rest or low

intensity exercise Are found in butter, margarine, vegetable oils Are source of fat-soluble vitamins and essential

fatty acids

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Proteins

Are chains of amino acids Can supply 4 kcal of energy per gram, but are not a

primary energy source Are an important source of nitrogen

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Proteins

Proteins are important for Building cells and tissues Maintaining bones Repairing damage Regulating metabolism Fluid balance

Protein sources include meats, dairy products, seeds, nuts, and legumes.

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Vitamins

Vitamins: organic molecules that assist in regulating body processes.

Vitamins are micronutrients that do not supply energy to our bodies.

1.Fat-soluble vitamins

2.Water-soluble vitamins

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Vitamins

Fat-soluble vitamins Vitamins A, D, E, and K Dissolve easily in fats and oils

Fat-soluble vitamins can be stored in the body.

Toxicity can occur.

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Vitamins

Water-soluble vitamins Vitamin C and the B vitamins Remain dissolved in water

Excess water-soluble vitamins are eliminated by the kidneys and cannot be stored in our bodies.

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Minerals

Minerals: inorganic substances required for body processes.

Minerals include sodium, calcium, iron, potassium, and magnesium.

Minerals have many different functions such as fluid regulation, bone structure, muscle movement, and nerve functioning.

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Minerals

Our bodies require at least 100 mg/day of the major minerals such as calcium, phosphorus, magnesium, sodium, potassium, and chloride.

We require less than 100 mg/day of the trace minerals such as iron, zinc, copper, iodine, and fluoride.

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Water

Water is a critical nutrient for health and survival.

Water is involved in many body processes.

fluid balance nutrient transport

nerve impulses removal of wastes

muscle contractions chemical reactions

many, many more…

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Determining Nutrient Needs

Dietary Reference Intakes (DRIs): updated nutritional standards.

Expand on the traditional RDA values Set standards for nutrients that do not have RDA

values

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Determining Nutrient Needs

DRIs identify the Amount of a nutrient needed to prevent deficiency

disease in healthy people Amount of a nutrient which may reduce the risk of

chronic disease Upper level of safety for nutrients

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Determining Nutrient Needs

Figure 1.8

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Determining Nutrient Needs

DRIs consist of four values1. Estimated Average Requirement (EAR)

2. Recommended Dietary Allowances (RDA)

3. Adequate Intake (AI)

4. Tolerable Upper-Intake Level (UL)

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Determining Nutrient Needs

Estimated Average Requirement (EAR) The average daily intake level of a nutrient that will

meet the needs of half of the people in a particular category

Are used to determine the Recommended Dietary Allowance (RDA) of a nutrient

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Determining Nutrient Needs: EAR

Figure 1.9

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Determining Nutrient Needs

Recommended Dietary Allowances (RDA) The average daily intake level required to meet the

needs of 97 to 98% of people in a given life stage and gender

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Determining Nutrient Needs: RDA

Figure 1.10

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Determining Nutrient Needs

Adequate Intake (AI) Recommended average daily intake level for a

nutrient Based on observations and estimates from

experiments Used when the RDA is not yet established:

calcium, vitamin D, vitamin K, fluoride

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Determining Nutrient Needs

Tolerable Upper Intake Level (UL) Highest average daily intake level that is not likely

to have adverse effects on the health of most people Consumption of a nutrient at levels above the UL is

not considered safe

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Determining Nutrient Needs

Estimated Energy Requirement (EER) Average dietary energy intake (kcal) to maintain

energy balance Based on age, gender, weight, height, and level of

physical activity

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Determining Nutrient Needs

Acceptable Macronutrient Distribution Ranges (AMDR)

The portion of the energy intake that should come from each macronutrient

The range of energy intake from carbohydrate, fat, and protein associated with reduced risk of chronic disease

The range of macronutrient intake that provides adequate levels of essential nutrients

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Determining Nutrient Needs: AMDR

Table 1.4

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Nutrition Research

The scientific method Observation: describe the phenomenon Create a hypothesis Design, collect, and analyze the data Interpret the data Generalize the findings, develop a theory

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Research Models

Epidemiological studies Human experiments

Case control studies Clinical studies

Animal studies

Note: Each type of study has advantages and disadvantages.

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Research Study Factors

Controls Does not receive treatment

Sample size Appropriate to measure a difference between

treatment groups

Placebo Similar appearance and taste

Double-blind Neither subjects nor researchers know who is in the

placebo or treatment groups

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Evaluating Media Reports

Ask these questions to determine the scientific validity Who is reporting the information? Who conducted the research and who paid for it? Is the report based on reputable research studies?

Was there a control and an experimental group? Was the sample size large enough to rule out

chance variation? Was a placebo effectively administered? Was the experiment double blind?

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Evaluating Media Reports

Is the report based on testimonials? Are the claims too good to be true? Prior to publication in reputable scientific journals

articles undergo peer review Experiments must be repeated to confirm or

disprove the findings

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Reliable Sources of Information

Trustworthy experts Registered dietitian (RD) Licensed dietitian Professionals with advanced degree(s) in nutrition Medical doctor