Nutrition Basics

Nutrition – the science of food with respect to the nutrients and other substances therein.


  • the actions and interactions of nutrients and their relationship to health and disease.
  • The process by which the body ingests, digests, absorbs, transports, utilizes, excretes food components



Digestion and Absorption




Water Soluble Vitamins

Fat Soluble Vitamins

Water, Minerals, Electrolytes

Window of Essentiality – the range of food intake levels, for essential nutrients, which are suitable for survival

Nutrients – chemical substance in food that nourish us by providing energy, materials for building body parts and factors to participate in the bodies chemical processes.

Classes of Nutrients:

  1. Carbohydrates
  2. Proteins
  3. Lipids or Fats
  4. Vitamins
  5. Minerals
  6. Water


Digestion – is the process where food is broken down into forms that can cross the GI tract wall and enter the blood and lymph.

Components of the GI tract:

  1. Mouth
  2. Oral cavity ( mucus, enzymes)
  3. Esophagus ( transports bolus)
  4. Stomach
  5. Small intestine (made up of duodenum, jejunum, ileum)
  6. Large intestine (made up of cecum, colon)


Mastication – Chewing

Swallowing – Deglutition

Peristalsis – the involuntary muscle action which moves food throughout the digestive system.

Chyme – when food becomes more liquid in form

Bile – is made in the Liver; and stored in the Gall Bladder

Pancreas fuction in digestion – secretes digestive enzymes

Absorption – process by which substances are transferred across the GI tract wall into the blood and lymph

Small Intestine – Primary Site of Nutrient Absorption

Large Intestine -Primary Site of Salt, water and Vitamin absorption

Salivary Amylase and Pancreatic Amylase – enzymes that break down starch ( CHO) into simple sugars

Lingual Lipase ( in saliva) and Pancreatic Lipase – enzyme that break down dietary lipids

Pepsin – enzyme that breaks down proteins into polypeptides

Emulsification – peristaltic action of small intestine that break large fat globules into smaller ones.

Chylomicrons – large lipoproteins that transport lipids from Small Intestine to other locations in the body by surrounding free fatty acids ( FFA) and monoglycerides (MG), and make them water soluble

Effects of Increasing blood alcohol level:

  • Short term : intoxication and depress CNS neurons
  • Long term: liver disease


– most important physiological consequence of carbohydrates intake is that it Maintains bodily levels of glucose

Monosaccharides – simple sugars

3 Important Dietary Monosaccharides

  1. Glucose
  2. Fructose – abundant in fruits
  3. Galactose – abundant in dairy products

Glucose – a monosaccharide; the body’s most important fuel source.

Glycogen – the stored form of glucose in the body; It is stored in the LIVER and the MUSCLES.
– known as Animal Starch

Maltose = Glucose + Glucose = known as malt sugar

Sucrose = Glucose + Fructose = known as table sugar and is abundant in sugar cane

Lactose = Glucose + Galactose = known as milk sugar and is found only in mammary glands of lactating animals ( not plants)

Plant Starch – the most abundant polysaccharide in the diet. Abundant in potatoes and rice.

Fiber – found only in plants

Soluble Fiber – dissolves or swell in water; metabolized by colonic bacteria

Good Sources of Soluble fiber:

  • Apple, bananas, oats, citrus fruits, legumes

Insoluble Fiber – fiber that, when it is consumed, just passes through the body and is excreted without getting absorbed into the bloodstream

Good sources of insoluble fiber:

  • Wheat bran, wheat products, whole grains, veggies

Dietary Fiber – acts as FILTER in food and provides satiety without overeating


  • 55% of caloric intake should be carbohydrates
  • 80% should be complex carbs, 20% or less should be simple sugars
  • Ideal fiber intake is 30-40 grams per day

Constipation is a consequence of excessive fiber intake.

LIPIDS: Triglycerides and Fatty Acids

Lipids – characterized by being ‘water insoluble’

Fats – triglycerides which are solid at room temperature

Oils – triglycerides which are liquid at room temperature

Saturated Fatty Acid – if all the carbon bonds in a fatty acid are single bonds

Monounsaturated Fatty Acid – if one double carbon bond exists in a fatty acid

Polyunsaturated Fatty Acid – if more than one double carbon bond exists


  • Unsaturated fatty acids are better because they are more natural and easier for the body to break down
  • If saturated fatty acids predominate, the trygliceride is usually a FAT
  • If unsaturated fatty acids predominate, the triglyceride is usually an OIL
  • 40% of the energy used by the body is derived from fatty acids ( when at rest and light activity)
  • Animal products are the major source of fats and fatty acids
  • Dietary saturated fat is associated with elevated LDL ( low density lipoprotein). This leads to Atherosclerosis and Heart Disease

Hydrogenation – the process by which food processors convert some of the unsaturated fatty acids in oils to saturated fatty acids.

Essential Fatty Acids – OMEGA -3 and OMEGA -6 ; they must be obtained nutritionally because they cannot be synthesized by the body.

Omega 3 Fatty Acids of Interest:

  1. LNA ( sources: canola oil, soybean, plant leaves, flaxseed)
  2. EDA ( sources: tuna, salmon, fish oil)
  3. DHA ( sources: tuna, salmon, fish oil)

Omega 6 Fatty Acid of Interest:

  1. Linoleic Acid ( souces: corn oil, soybean oil, safflower oil)

Physiological Importance of Triglycerides:

  • Storing Energy
  • Insulation
  • Transporting Fat- Soluble Vitamins ( A, E, D, K)
  • Provides Satiety


  • Cholesterol is a vital component of Brain and Nerve cells
  • Excessive cholesterol speeds the development of atherosclerosis and heart disease
  • 2 ways the body gets cholesterol: LIVER SYNTHESIS & DIET ( animal food, dairy)
  • Phospholipids are a major component of Cellular Membranes and even though there are a lot of sources of phospholipids, our body synthesizes all the phospholipids it needs

Recommended intake levels of Lipids:

  • No more than 30% of your caloric intake should be lipids
  • Saturated fats should not exceed 10% of caloric intake
  • Omega 3 should comprise 0.5%
  • Omega 6 should comprise 3%
  • Trans fat should be taken in Trace amounts


Proteins – made up of amino acids linked by peptide bonds
– it is important to take in protein because it gives our body its only useable source of NITROGEN

Essential Amino Acids -the body cannot synthesize them and they must be obtained from the diet

Semi -Essential Amino Acids– they can be synthesized from Essential amino acids if they are provided nutritionally

Non – Essential Amino Acids -the body can synthesize them

  • The body needs 20 different amino acids to function
  • There are 9 Essential Amino Acids
  • 2 Semi -Essential Amino Acids
  • 9 Non -Essential Amino Acids
  • Metabolism of amino acids for energy accounts for about 10% of energy use in the body

Important Functions of Amino Acids in the body:

  1. Protein synthesis
  2. Conversion to other amino acids
  3. Special functions ( precursor to formation of important physiological compounds)
  4. Conversion to Glucose
  5. Energy
  6. Conversion to Fat

Gluconeogenesis – the formation of glucose from other metabolites and not from glycogen

Important Functions of Proteins in the body:

  1. Stuctural – (muscle, bone, Connective tissues…)
  2. Regulatory – (enzymes…)
  3. Fluid Balance – (protein in tissues provides osmotic pressure to pull back liquid in tissues)
  4. Transportation – ( hemoglobin…)
  5. Acid- Base balance – ( pump ions in and out…)


  • Proteins are the main structural components of Muscle, Connective Tissue, Bone, Matrix, Organs
  • Animal Meats are the most nutrient dense source of protein
    • Water packed tuna – 85%
    • Chicken – 70%
    • Beef – 45%
  • The most protein- dense plant foods are LEGUMES
  • For adults over 19 years, the Recommended Daily Intake of protein is 0.86 grams per kilogram of body weight.
  • High protein diets can be damaging to the Kidneys
  • Protein Malnutrition causes Edema, Tissue wasting, stunted growth

Water Soluble Vitamins

Vitamins ( co-factors)– are organic compounds which occur naturally in foods which are needed for normal metabolic functioning
– generally must be obtained nutritionally ( body cannot synthesize them)

Too much of a vitamin is called toxicity, too little is deficiency

Vitamin B – rarely reach toxic levels because they are water soluble, so excess of it are excreted in the urine

1. Vitamin B Complex:

– Thiamin ( Vit B1)

– Riboflavin ( Vit B2)

– Niacin ( Vit B3 )

– Pyridoxine ( Vit B6)

– Cyanocobalamine ( Vit B12 )

– Pantothenic acid

– Folic acid ( or folate)

– Biotin

a. Vitamin B1- Thiamin
Best : pork, “enriched foods” ( enriched usually only B1,B2,B3)
Good: sunflower seeds, whole grains, legumes

Deficiency Seen in : people in poverty and alcoholics
One sign of deficiency: Beriberi

b. Vitamin B2 – Riboflavin
Best: dairy products, “ enriched foods”
Good : mushrooms, spinach

Deficiency Seen in : alcoholics; people lacking in dairy products in their diet
One sign of deficiency: inflammation of mouth and tongue; cracks at the corners of the mouth

c. Vitamin B3- Niacin
Good: Mushrooms, bran, tuna, salmon, meats, asparagus, peanuts, “ enriched foods”

Deficiency Seen in : alcoholics; people whose diet consist of corn and corn products
One sign of deficiency: muscle weakness

d. Vitamin B6- Pyridoxine
Best: fish and poultry
Good : bananas, spinach

Deficiency Seen in : adolescent; adult and elderly women
One sign of deficiency: seizures

e. Pantothenic Acid
Best : peanuts, egg
Good : most vegetables, milk

f. Vitamin B12- Cyanocobalamine
Best : organ meats
Good : dairy products, animal meats

Deficiency Seen in : elderly and vegetarians
One sign of deficiency: tingling sensations

  • Lack of Vitamin B12 leads to FOLATE deficiency
  • Folic acid depends on Vitamin B12 for activation
  • Unlike other water-soluble vitamins, Vitamin B12 can get stored in the body
  • Deficiency of folic acid is seen in pregnant women
  • One sign of folic acid deficiency is MEGOBLASTIC ANEMIA
  • One good source of folic acid is vegetables and best source of folic acid is green leafy vegetables
  • Food preparation ( particularly heat) can destroy 50%-90% of folate contents in foods, this makes Orange Juice a good source
  • Vitamin C is known as ASCORBIC ACID

g. Biotin
Good source: cheese

One sign of deficiency: dermatitis

Fat Soluble Vitamins ( A, E, D, K)

  • Fat soluble vitamins are stored in the LIVER and FAT TISSUE

Vitamin A

  • Around 90% of Vitamin A is stored in the liver
  • People who have low intake of Vitamin A have increased risk of infection because of the decrease in their mucous production

Symptoms of Vitamin A Deficiency: dry mucus membrane , night blindness, poor growth

Sources of Provitamin A: plant foods ( sweet potatoes, broccoli, spinach)

Sources of Preformed Vitamin A: animal foods ( liver, fish oil, milk, butter)

Functions of Vitamin A:

1. Vision — retinol ( a retinoid) = necessary for triggering visual responses and adjusting to dim light

– Production of corneal mucus ( mucus of cells lining cornea. Not tears)

2. Epithelial Cell Growth

– Body surfaces that produce mucus are dependent on Vitamin A to avoid deterioration of mucous forming cells ( skin, GI, urinary, eyes, lungs)

3. Growth and Reproduction

– Vitamin A required for bone maintenance, cellular division and normal immune response

4. Cancer Prevention

– Carotenoids are antioxidants and therefore deactivates harmful compounds like free radicals

Vitamin D

  • Without Vitamin D, we lose the ability to ABSORB, RETAIN, and DEPOSIT calcium.
  • Rickets – Vitamin D deficiency in infants
  • Osteomalacia -Vvitamin D deficiency in adults
  • When Vitamin D level is too high, it results in CALCIUM DEPOSITS in the kidney and other organs

At risk for Vitamin D deficiency: people with kidney liver disease, people not receiving adequate sunlight, people who have fat malabsorption ( cystic fibrosis)

Dietary Sources of Vitamin D: fortified milk, fish oils, tuna, salmon

Non-Dietary Source of Vitamin D : sunlight

Vitamin E

  • Vitamin E is the vitamin most noted for its anti-oxidant and anti-aging properties

Vitamin K

  • 50% of Vitamin K absorbed daily by the body is obtained from intestinal bacteria.
  • The main function of Vitamin K is BLOOD CLOTTING
  • A symptom of deficiency of Vitamin K is: poor blood clotting or haemorrhaging


  • Around 60% of a person’s body weight is water


  • In terms of energy expenditure, it is a good idea to hydrate with 1ml of water for every calorie of energy expended.
  • CAFFEINE and ALCOHOL act as diuretics that cause excess water to be lost as urine
  • 20%+ water loss in the body can cause DEATH.

Major Functions of Water:

1. Medium: Water is the basic medium of ICF + ECF; Every cell is bathed in fluid and contains fluid (mostly water) in which ions, organelles, enzymes, other components are dissolved/ suspended.

B. Waste Removal: Most toxins or unstable products on body are converted to water- soluble compounds- can be excreted in water of urine.

C. Temperature Regulation: regulates temperature changes and stabilizes body temperature.


Electrolyte – any substance containing free ions that make substance electrically conductive

Ion – an atom or a molecule where the number of electrons is not equal to the number of protons, giving it a net positive or negative electrical charge.

Function of Some Electrolytes in the Body:

Sodium – key for retaining body water; make up major part of ECF
– Sources: table salt; processed foods

Chloride – component of stomach acid; aids in nerve impulse action
– Sources: table salt; processed foods
– Excessive vomiting can lead to chloride deficiency due to loss of stomach acid, may result in convulsions

Potassium – aids in fluid balance; make up major part of ICF; aids in nerve impulse action


  • Post menopausal women absorb the least amount of calcium
  • Absorption of Calcium:

– enhanced by vitamin D, phosphorus, lactose, glucose, estrogen

– hindered by high fiber

  • iron in spinach and legumes has bioavailability factor ( more available for our body)
  • ANEM IA and FATIGUE are symptoms of iron deficiency

1. Calcium

Functions: Bone and teeth strength ( ~ 99% of calcium is in bone); Nerve impulse transmission; Muscle contraction

Sources: Dairy, canned fish, leafy vegetables , tofu

2. Phosphorus

Functions: Components of bones + teeth ( ~85% in bones); Components of enzymes and DNA

Sources: Dairy, meat, processed food

3. Magnesium

Functions: Component of enzymes; Nerve + heart function

Sources: Whole grains, broccoli, squash, nuts, chocolate

4. Sulfur

Functions: Component of amino acids, vitamin; Important part of liver’s detoxification pathways; Help body’s acid base balance

Sources: Wheat bran, green vegetables, nuts

5. IronFunctions: Part of haemoglobin; Component of enzymes in respiration; Needed for immune function

Sources: Most nutrient- dense sources are: spinach, oysters, liver, legumes, grains and meat ( best) BUT: iron in spinach + legumes has bioavailability factor ( more available for our body)

6. Fluoride

Function: Aids in making teeth acid-resistant

Sources: Fluorinated water, toothpastes, seafoods