THE CARIBBEAN HEALTHWORKSPROJECT

Digestion & Nutrition

Digestive System

Digestion Absorption Digestive Organs Enzymes & Hormones Common Digestive Disorders

Digestive System

Digestion: breaking food into components small enough to be absorbed by the body.

Digestion occurs before entry of nutrients into circulation. Absorption: movement of nutrients, including water and

electrolytes across intestinal wall and into blood and lymph.

Digestive System: including the mouth, pharynx, esophagus, stomach, pancreas, gallbladder, liver, small/large intestines.

Whole Body System

Digestive system does not act alone. Endocrine system: stimulates hormones. Nervous system: send signals that control passage of

food, control hunger, etc. Cardiovascular system: transports nutrients to cells. Urinary and Integumentary system: eliminate waste.

Gastrointestinal (GI) Tract

Long hollow tube about 30 feet in length that runs from the mouth to the anus.

Transit time = 24 to 72 Hours

Transit time affected by composition of diet, physical activity, emotions, medications and illnesses.

Secretions

Mucus – moistens, lubricates, protects

Enzymes - protein molecules secreted by the pancreas that aid in digestion.

Hormones – chemical messengers that are secreted into the blood by one organ to regulate bodily function elsewhere.

Immune System

70% of the immune system is located in or around the digestive tract

Underneath the mucosal lining of the stomach is lymphatic tissue

Constantly assessing good vs. bad

Secretory IgA antibodies are present in gut mucosa

Digestion Begins in the Mouth

Just the smell of food starts saliva flowing Chewing increases the surface area of food and

allows for the mixing of saliva. Saliva: 99.5% water and amylase – Moistens food

and carries dissolved food molecules to taste buds Salivary amylase: breaks starches into sugars.

Pharynx

Shared by the digestive tract and the respiratory tract

Funnel shaped opening the connects the nasal passages and mouth to respiratory passages and esophagus

Common passageway for air and food and is responsible for swallowing.

Esophagus/Peristalsis

Tube extending from mouth to stomach Peristalsis: wave like flow to move food toward

stomach Esophageal sphincter protects food once in the

stomach from moving back to the esophagus Reflux is caused by weakening of the sphincter

The Stomach

Temporary storage place for food While in the stomach food mixes with HCL Only some water, alcohol, and a few drugs like

Tylenol are digested here Food exits through P.S.

Gastric Juices

The stomach contains gastric glands HCL kills most bacteria HCL stops action of salivary amylase HCL starts the digestion of protein by activation of

the enzyme pepsin HCL drops the pH of the stomach from 3.5 – 4 to 1-

2 (only acidic environment in the body)

Ulcers

Stomach lining protected by mucus Ulcers form when acid/pepsin penetrate mucus Typically caused by poor diet and bacterial

infection (Heliobacter pylori or H Pylori)

Gastric Triggers

Churning and acid production is regulated by signals from hormones and nerves

These signals come from the brain, stomach and small intestine

The thought and sight of food causes the brain to tell the stomach to release gastric juices

Food local nerve signals brain to release gastin(hormone that triggers HCL release/stomach motility)

Gastric Triggers

Food small intestines hormonal and nervous signals decrease stomach motility/secretions

A hormone CCK signals the release of leptin – a hormone that tells the brain to signal fullness

Once empty another hormone – ghrelin is produced that tells the brain to send a signal of hunger

Stomach Emptying

Stomach empties in 2-6 hours Determined by the size and composition of the meal To move into the small intestines food passes through

the pyloric sphincter Food composition affects transit time Emotions affect transit time

Transit Time

Large meal moves slower than small one Solid meal moves slower than a liquid one Mixed meal takes 4 hours Higher fat slows transit Protein alone moves faster than with fat Carbohydrates move the quickest Sadness/fear slow movement Aggression/anger speed movement

Small Intestines

Narrow tube – 20 feet in length- Duodenum: 1st 12 inches- Jejunum: Next 8 feet- Illeum: Last 11 feet

The small intestine is the main site for digestion and absorption of water, vitamins, minerals, CHO, fat, and protein

Accessory organs (pancreas/gallbladder) aid in digestion

The Pancreas: Exocrine Tissue

Secretes pancreatic juices Bicarbonate: brings pH up Enzymes: Amylase, Trypsin/Chymotrypsin and

Lipase

Digestive Enzymes

Protein molecules that aid in the breakdown of food for absorption

Food needs to be broken down into smallest molecules before they can be absorbed

Lipase breaks fats into fatty acids and glycerol Amylase splits carbohydrates into simple sugars Protease breaks proteins into single amino acids

The Pancreas: Endocrine Tissue

Produces 2 very important hormones: Insulin and Glucagon

Insulin: released when blood sugar rises allowing muscles and other tissues to take in glucose for fuel

Glucagon: released when blood sugar is low, causing liver to break down glycogen and release to the blood

The Gallbladder

Stores and secretes bile Bile: produced by the liver, necessary for digestion

and absorption Secreted in the SI, mixes with fat, and breaks it into

smaller globules, allowing lipases to access it

Diffusion

Movement of substances from one area of higher concentration to an area of lower concentration (Water)

Simple diffusion: no energy required Facilitated diffusion: helped by carrier protein, no

energy required Active Transport: Needs both carrier protein and

energy

Lining of the SI

Large surface area for absorption (the size of a tennis court)

Intestinal walls arranged in circular/spiral folds, Villi, Microvilli (brush border)

The villi contain one cell layer that needs to be crossed to reach the bloodstream / lymphatic system

Getting Nutrients to the Cells

Once absorbed nutrients have to be sent to the rest of the body

AA and sugars enter the bloodstream at the intestine and travel to the liver

Fat travels via the lymphatic system before entering the blood

Blood Flow

When at rest: ¼ blood goes to the GI, 1/5 to your skeletal muscles, and the rest goes to the heart, kidneys, brain, skin and other organs

Changes when you eat and exercise When you are exercising – 85% goes to the

skeletal muscles to deliver oxygen When you eat a large meal more blood flows to

help digest it

The Liver: Gatekeeper

Amino acids, sugars, water-soluble vitamins cross the mucosal cells and end up moving to the hepatic portal vein which goes to the liver

In the liver they are processed, some stored, or sent to general circulation

The liver modifies products of protein breakdown to make them safe to get to the kidneys

Lymphatic System

System of vessels, organs, and tissues that drains excess fluid from the spaces between cells, transports fat-soluble substances from the digestive tract, and contributes to immune function

Functions in the absorption and transport of fat-soluble substances (cholesterol, long chain fatty acids, fat-soluble vitamins)

These substances do not go to the liver first before the bloodstream

Large Intestines

Anything that has not been absorbed by the SI moves into the LI

LI is – 5 feet long and includes colon and rectum Slow movement: fecal matter may stay in LI up to

24 hours which favors growth of bacteria

Intestinal Microflora

Permanent residents of the LI (300 – 500 different species)

Bacteria in gut – 10 x greater than cells in the body Breakdown unabsorbed portion of food (fiber) Producing nutrients for bacteria to flourish These micronutrients synthesize some of the B

vitamins and Vit K, which are absorbed This breakdown produces flatulence

The Colon

Colon absorbs small amounts of water and electrolytes

Material not absorbed is excreted Feces – undigested matter, dead cells, water,

bacteria Amount of water in feces depends on fiber and

water

The Rectum

End of the colon Feces stored prior to excretion Connected to the anus Defection regulated by a sphincter that is under

voluntary control

Common Digestive Problems

Reflux IBS IBD ( Crohn’s or Ulcerative Colitis) Lactose Intolerance Constipation/Diarrhea Celiac Sprue Gallstones

Reflux (GERD)

Acid from stomach re-enters esophagus Often related to obesity Dietary components include:

- Lowers LES:chocolate, caffeine, coffee, tea, peppermint, spearmint, alcohol

-Increased HCL: large portions, fatty foods, spices, tomato products, citrus

Avoid eating close to bedtime Eating too fast and high stress play a role Some medications cause such as Fosamax

Constipation

Usually caused by lack of fiber and/or fluids Lack of exercise plays a role Can be caused by medications such as iron

supplements, calcium supplements Increase fiber in the diet with fruits, vegetables,

whole grains, legumes, flaxseeds Magnesium Add exercise Probiotics

IBS (Irritable Bowel Syndrome)

Can cause constipation or diarrhea, bloating, gas and abdominal pain

Can be triggered by stress, food intolerance, high far, lactose intolerance, hormone imbalances, or environmental sensitivities

Low fat, high fiber, dairy free diets work best Exercise and stress reduction helps a great deal Some people are sensitive to fructose or mannitol

IBD (Inflammatory Bowel Disease)

Crohn’s Disease/Ulcerative Colitis Inflammation of digestive tract Can cause pain, bloody diarrhea, cramping, fever,

weight loss and FTT in children Usually sensitive to dairy and grains On low fiber diet when in active flare-up Probiotics and digestive enzymes work well Specific Carbohydrate Diet (Elaine Gotschall)

Diarrhea

Can be caused by bacteria, virus, food intolerances (lactose intolerance), medications

Avoid high fiber foods Add banana and white rice Remove intolerant food Add probiotics Fermented foods

Gallstones

Most common disorder of the gallbladder Often related to diet Low fat, low meat, high fiver diet recommended Limit coffee, increase water (coffee triggers CCK

which stimulates the gallbladder) Maintain healthy weight Exercise reduces the risk

Celiac Disease

Gluten Intolerance: genetic/inheritable disease Gluten: protein found in wheat, barley, rye and

?Oats Autoimmune response that damages SI decreasing

the ability to absorp nutrients and can lead to many deficiencies if left untreated

Only treatment is to avoid gluten

Macronutrients

Carbohydrates Fiber Lactose Intolerance Proteins Vegan Dishes Fats Toxins

Carbohydrates

Makes up the largest group of food Found only in plant foods with the exception of

lactose All fruits, vegetables, grains, legumes, nuts and

seeds Should make up 50-60% of daily calories Provide 4 calories/gram

Whole vs. Refined

Whole Grain: foods that have not been significantly altered from how they occur in nature

Refined (processed): foods that have undergone processing to remove the coarse part of their original form

Refining

Milling process separates the layers White flour – milling only the endosperm White flour is enriched (thiamin, riboflavin, niacin,

and iron) Refined sugars are added to many foods Once sugar is removed from its plant source it no

long contains fiber, vitamins or minerals Empty Calories

What are carbs?

Chemically they all contain carbon, hydrogen, and oxygen molecules

Classifications include: Simple Carbohydrates Complex carbohydrates: starches and fibers

Simple Carbohydrates

Monosaccharide (mono – one) simple sugar molecule

Disaccharide (Di – two) two sugar molecules linked together

Glucose, fructose, galactose Each contain 6 contain, 12 hydrogen, and 6 oxygen

but differ in arrangement

Simple Sugars

Glucose: most important fuel for the body – blood sugar

- Rarely found alone in nature – usually found as part of a disaccharide

Fructose: found in fruit, vegetables, honey, tastes sweeter than glucose

Galactose: rarely found alone in nature, usually part of lactose

Disaccharides

Maltose (glucose and glucose)- Forms when starch is broken down, provides sweet taste when bread is chewed

Sucrose: table sugar (glucose and fructose)- Sugar cane, sugar beets, honey, maple syrup- Only sweetener that can be labeled as sugar

Lactose: milk sugar (glucose and galactose) - Only sugar found naturally in animal foods

Glycogen and Starch

Glycogen: storage form of glucose in animals Starch: storage form of CHO in plant

- When we eat starch we are eating stored energy- Potatoes – starchy root- Legumes/grain – starchy seed

Starches are thickeners when heated

Fiber

Cannot be digested by human enzymes Soluble fiber: absorbs water and increases weight

of feces- Can be absorbed by bacteria in LI and cause gas- Oats, fruit, beans, seaweed, pectin

Insoluble fiber: does not absorb water, increase bulk of stool and speeds transit time

- Wheat, rye, vegetables

Benefits of Fiber

Promotes healthy gut function by stimulating peristalsis – muscles of the colon work harder and get stronger

High fiber diets increase transit time High fiber can cause constipation without enough

water Soluble fibers and oligosaccharides promotes

healthy gut flora Reduces cholesterol

Low Fiber Diets

Constipation Diverticulosis Hemmorrhoids Some evidence of increased colon cancer risk Obesity Diabetes

Carbohydrates = Energy

Glucose: main energy source for the body In the body glucose is broken down into carbon

dioxide, water and ATP Glucose not needed is stored: glycogen Glucose can be made from protein Energy can be made from fat: ketone productions

(low CHO diets)

Glycemic Response

How quickly blood sugar rises after food is consumed

Affected by the amounts and type of CHO, protein and far in the meal

Affected by how quickly food leaves the stomach Refined CHO leaves the stomach quickly Whole foods (fiber) leave slowly Fat and protein leave the stomach slowly

Carbohydrate Digestion

Begins in mouth pancreatic enzymes absorbed by brush border

Sugars broken down in mono/disaccharides before absorption transported to the liver

Glucose stored in the liver and sent to the organs via blood

Substances not completed digested LI and are utilized by bacteria

Insulin’s Role

Allows cells to take in glucose Promotes storage of glycogen by the liver Leads to uptake of glucose for energy and synthesis

of glycogen in muscle Promotes protein synthesis in muscle Promotes conversion of glucose to fat in fat cells

Lactose Intolerance

Newborns almost always produce lactase (enzyme to digest milk)

As we age lactase is produces less and less Lactose not digested in the SI therefore moves to LI

for bacteria to attack The undigested lactose, acids and gas draws water

to the LI causing diarrhea -100% Asians/ African, - 30-50% other Americans

Lipids (Fats)

Group of molecules most of which do not dissolve in water

Fats give food texture, flavor, aroma and calories Lowering the fat in the diet doesn’t necessarily

make it healthier Fat should make up -30% of daily calories 9 calories/gram

Fats in the Body

Provide structure, regulation and energy Stored as adipose tissue under skin and around

organ Insulates the body and protects the body from shock Important structural part of cells Lubricates body surfaces Used to make hormones

Triglycerides

Major form of lipid in food and the body- Contains 3 fatty acids and a glycerol backbone- Each fatty acid is a chain of carbon atoms with an acid group on the end

The fatty acids can be either saturated or unsaturated

Saturated Fatty Acids

All carbon atoms in the fatty chain are saturated with hydrogen (no double bonds)

Found mostly in animal foods (meat/dairy) Solid at room temperature with the exception of

tropical oils High intakes leads to high cholesterol, heart

disease, etc.

Unsaturated Fatty Acids

Contain some carbons that are not saturated with hydrogen

Tend to be liquid at room temperature Monounaturated: olive, canola, peanut oil Polyunsaturated: linoleic acid, corn, safflower,

soybean oils

Omega Fatty Acids (Poly)

Omega-3 fatty acids – (linolenic): flaxseed, walnuts, fatty fish

- Anti-inflammatory fat- We need to increase our intake

Omega-6 fatty acids )linoleic): nuts, corn, safflower, and sunflower oils

- Pro-inflammatory far- We need to decrease our intake

Essential Fatty Acids

Omega-6: growth, skin integrity, fertility, maintaining RBC structure

Omega-3: structure and function of the cell membranes (retina, CNS)

EFA Deficiency: scaly, dry skin, liver abnormalities, poor wound healing, impaired vision & hearing, growth failure in infants

Cholesterol

Needed in the body but not essential: produced by the liver

Part of the cell membranes Part of myelin (coating on nerve cells) Needed to synthesize vitamin D in the skin Part of bile acids and hormone Found in animal food only

Lipid Digestion

Lipids need help moving through the body because they do not mix with water

Fat absorption occurs in the SI Bile, secreted by the gallbladder, breaks down

small fat droplets which can then be broken down further by enzymes

Lipid Absorption

Micelles: mixture of digested fatty acids, bile, and fat-soluble vitamins

Once absorbed enters the lymph and finally blood

Over-consumption of Fat

Obesity Cardiovascular disease/Atherosclerosis Elevated cholesterol/triglycerides Cancer Fatty liver Diabetes Gallbladder disease

Protein (Amino Acids)

Animal food, legumes, soy, nuts, bread, rice and pasta all have protein

Animal protein: provides B vitamins and minerals such as iron, zinc and calcium but has no fiber and is often high in fat and cholesterol

Plant protein: provides fiber, iron, zinc, calcium, phytochemicals, unsaturated fats, but does not provide certain B vitamins (B12)

Protein

Made up of amino acids:20 total in protein (9 essential)

Amino acids are strung together in chains Needed for the building/repair of muscles, tissues,

organs etc. Should make up – 10-15% of daily calories 4 calories/gram

Amino Acids

Essential NonessentialHistidine - Alanine- Isoleucine - Arginine- Leucine - Asparagine- Lysine - Aspartic acid- Methionine - Cysteine- Phenylalanine - Glutamic acid- Threonine - Glutamine- Tryptophan - Glycine- Valine - Proline

- Serine- Tyrosine

Protein Digestion

Proteins must be digested to be absorbed Digestion begins within the acidic stomach Broken into smaller chains before entering the SI Amino Acids compete with each other for the

transport system Move to liver and finally blood stream once past

the brush border

Functions of Protein

Collagen: most abundant protein in body- Holds cells together and forms framework of bones and teeth

Enzymes Transport protein Skin, hair, nails, muscles, organs, bones Hormones Regulate fluid balance Regulates pH balance

Compounds Made From AA

Amino acid chains contain a nitrogen compound Nitrogen: Non-protein compound needed to make

neurotransmitters (tryptophan needed for serotonin) DNA/RNA are also nitrogen-containing compounds Skin pigment (melanin) Niacin Creatine (fuels muscle contraction) Histamine (causes blood vessels to dilate)

Food Allergies

Triggered when a protein from the diet is absorbed without being completely digested

Milk, eggs, peanuts, tree nuts, wheat, soy, fish and shellfish

First time this happens, immune system is triggered When it happens again immune system attacks

causing allergic reaction

Excess of Protein in the Diet

Excess amino acids cannot be stored therefore they are…

- Used for energy if your body does not provide enough carbohydrate and fat

- Converted to fatty acids and contribute to weight gain

Dangers of High Protein Diets

Protein breakdown byproducts (urea) must be eliminated which increases water loss

Increases excretion of calcium in urine: kidney stones and bone loss

Long term excess of protein intake may lead to kidney and liver damage

Typical high protein diets are low in fruits, vegetables, fiber, and high in saturated fat

Protein Supplements

Often sold to promote immune function, healthier hair/nails, stimulate muscle growth

This will only happen if your diet is deficient in protein

Eating more protein does not build you more muscle (must lift weight)

Avoid taking separate amino acids

Micronutrients

Vitamins: A, C, D,E,K, thiamin (B1), riboflavin (B2), folic acid, niacin (B3), biotin, pantothenic acid, B6, B12

Minerals: Calcium, magnesium, Iron, Potassium, Sodium

Toxins

Air we breath, food we eat, and byproducts of metabolism

These can cause irritation and inflammation throughout our body

Liver is gatekeeper We remove toxins in sweat, feces, urine etc. Best way is to limit exposure (eat organic, avoid

highly processed foods, alcohol, drugs, sugar substitutes)