Nutritional Science prelim 1

Nutrition

is the sum total of processes involved in the intake and utilization of food substances by living organisms, including ingestion, digestion, absorption, transport, and metabolism of nutrients in food.

metabolism

encompasses all chemical processes that occur within a living

organism (a cell) to maintain life.

• Food → Energy

• Oxygen → Carbon dioxide (CO2)

nutrients

a substance found in foods that performs one or more physiological or biochemical functions in the body.

essential nutrients

A substance that must be obtained from the diet, because the body needs it and cannot make it in the required amounts.

nonessential nutrients

A substance found in the body and used by the body to promote health but not required to be consumed in the diet.

Ex: cholesterol (Found in different foods that we eat (like milk), Produced in the body), carnitine, creatine, and some amino acids

conditionally essential nutrients

Normally nonessential nutrient, but under certain circumstances it becomes essential

Ex: creatine when someone has Chronic Kidney disease (CKD)

macronutrients

(> 1g/day) To preserve normal body functions, the human body needs these nutrients in large quantities

micronutrients

phytochemicals

zoonutrients

Dietary Reference Intakes (DRI)

Documents issued by the Food and Nutrition Board:

1. Information on basic function of nutrients, food sources, and effects of deficiencies and excessive intakes.

2. Offer quantitative estimates of nutrient intakes to maintain health in US and Canada.

3. Addresses issues of safety, quality, and adequacy of the food supply.

major function of nutrients

• Energy - All three macronutrients provide energy, but the body relies primarily on CHO and fat

• Structure - Promote tissue growth and development, mostly proteins

• Regulation - All nutrients

classification of nutrients

• organic/inorganic

• essential/non-essential or conditionally essential

• energy-yielding/non-energy-yielding

• macronutrients/micronutrients

Organic nutrients

Molecules with carbon atoms

Ex: carbohydrates, protein, lipids/fats, alcohol, vitamins

Inorganic nutrients

Molecules without carbon atoms

Ex: water, minerals

Energy Balance

Energy intake must be matched with energy expenditure to ensure balance

Energy Intake: CHO, proteins, lipids/fats, alcohol

Energy expenditure: basal metabolism, thermogenesis, physical activity

Basal (resting) metabolic rate

energy needed to perform normal body functions (respiration, circulation, digestion)

Thermogenesis

the energy cost of food processing (ingestion, digestion, absorption, transport, and storage)

Total energy expenditure =

basal metabolism + thermogenesis + physical activity

Joule (J):

1 out of 4 units to represent energy expenditure and energy released from foods

The SI unit of energy. Defined as 1 newton of force acting over 1 meter). Too small for food, so nutrition labels use kilojoules (kJ).

calorie (cal, lowercase c):

1 out of 4 units to represent energy expenditure and energy released from foods

Energy to raise 1 g of water by 1 °C.

kilocalorie (kcal):

1 out of 4 units to represent energy expenditure and energy released from foods

1,000 cal. Energy to raise 1 kg (1 L) of water by 1 °C

Calorie (Cal, capital C):

1 out of 4 units to represent energy expenditure and energy released from foods

the "large" or food Calorie. 1 Cal = 1 kcal. A 19th-century convention that’s used in US food labeling

4,148 joules (J) =

1,000 cal = 1 kcal = 1 Calorie

Who is Dr. Atwater?

an agricultural chemist and a pioneer in the study of modern nutrition.

He is best known the Atwater System to calculate the energy available in foods.

Energy vs non-energy-yielding nutrients

Energy-yielding: Lipids/Fats (9 kcal·gram-1), Carbohydrates (4 kcal·gram-1), Proteins (4 kcal·gram-1), Alcohol (not a nutrient, 7 kcal·gram-1)

Essential, but not energy-yielding nutrients: Vitamins (A, C, D), Minerals (Iron, calcium, & iodine)

Water

(~2.4 L/day) essential nutrient

• From liquid or solid/semisolid food intake, and oxidation of food.

We need water for:

• Transport of nutrients, gases, and waste products

• Medium for chemical reactions

• Body temperature regulation

Folate deficiency during gestation

• Neural tube defect due to folate deficiency.

• Failure of adequate spinal column and nerve development.

• Can result in mild to severe life-long disability.

• Treatment is mainly supporting the disability.

• Key is to prevent neural tube defects with folic acid supplementation.

Impact of nutrition in human diseases

1. etiology (causation)- nutrition deficiency and/or excess can play roles in causing diseases

2. Disease progression- nutritional status can affect one’s severity and recovery

3. Disease monitoring- certain nutrients can be useful biomarkers (ex. blood glucose level in diabetes)

4. Therapeutics- roles in both disease prevention, active intervention/cure, supportive treatment of diseases