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)