Chapter 18

Nutrients

substances needed for bodily function and are essential for life

nutrition

study of nutrients and their actions, interactions, and contribution to a healthy body

nutrients provide three vital functions

• provision of energy required by cells (carbs and fats)

• promotion of growth and development (proteins)

• regulation of metabolism (vitamins, minerals, water)

macronutrients 

• carbohydrates

• proteins

• lipids (fats) 

• water

key functions of carbohydrates

• fuel for cells

• comprise components of cell membranes

• indigestible carbohydrates (fiber) provide health benefits

simple carbohydrates

• monosaccharides - glucose, fructose, galactose

• disaccharides - sucrose, maltose, and lactose

complex carbohydrates

• oligosaccharides (3-10 monosaccharides)

• polysaccharides (11+ monosaccharides)

oligosaccharides

human digestive enzymes cannot breakdown, and most pass through the digestive tract without being absorbed

Fiber health benefits

• promotes bowl movements

• helps maintain bowel health 

• reduced risk of cardiovascular disease 

key functions of proteins

• serve as contractile elements for muscles, membrane transporters, enzymes, hormones

• comprise 17% of body weight

• body requires 20 amino acids

nonessential amino acids

amino acids that can be synthesized in the body

essential amino acids

amino acids that can’t be synthesized in the body, must be consumed in diet

classes of lipids

• triglycerides 

• phospholipids

• sterols 

key functions of lipids

• triglycerides provide major source of stored energy

• triglycerides serve as storage depot for fat-soluble vitamins

• phospholipids are needed for cell membranes

• cholesterol is required to synthesize substances (vitamin d, cortisol)

key functions of water

• major component of blood, saliva, mucus, sweat, and joint fluid

• plays important role in digestion and transportation of nutrients

two major compartments of water

• intracellular 

• extracellular 

vitamin requirements

• body cannot synthesize/ make enough of

• must be found naturally in foods

• when missing from diet, health problems occur

antioxidant vitamins

• protect cells against free radical damage

• (Vitamins c and e) 

major minerals

required in more than 100mg/day

trace minerals

required in less than 100mg/day

dietary reference intake (DRI)

• umbrella term that includes six sets of standards for dietary intakes

recommended daily allowance (RDA)

quantity of each nutrient to meet needs of 97-98% of healthy people in specific life stage

adequate intake (AI)

nutrient level that are assumed adequate

estimated energy requirement (EER)

average dietary energy intake predicted to maintain energy balance for healthy person maintain current weight

Estimated average requirement (EARs)

daily intake of a nutrient that will meet the needs of 50% of people in a specific age group

carbohydrate % of total energy intake

45-65%

fats % of total energy intake

20-35%

protein % of total energy intake

10-35%

dietary carbohydrates should be

complex carbs (fruits and vegetables)

glycemic index

measurement of how much a specific carbohydrate food elevates blood glucose levels

loss of 2% of body water

negatively impacts endurance exercise performance

loss of 3-4% body of water

results in fatigue, headaches, and dizziness

adequate intake of water

2,7L/day women, 3.7 L/day men

hyponatremia

happens due to too much water, which dilutes sodium in body

BMI

• weight (kg) divided by height (m²)

underweight BMI

<18.5 kg/m²

normal BMI

18.5 - 24.9 kg/m²

overweight BMI

25. 0 - 29.9kg/m²

obesity BMI

>30.0kg/m²

energy balance equation

energy intake minus energy expenditure (REE + PA/E + TEF)

components of daily energy expenditure

• Resting energy expenditure (major one)

• Physical activity/exercise energy expenditure

• Thermic effect of food

types of adipocytes

• white adipocytes - most abundant

• beige adipocytes - can make more when exercising in cold temp

• brown adipocytes - small amount

loss of lean mass results in

• loss of strength

• decreased resting metabolic rate

• loss of organ mass - reduced function