Nutrition Module 2

Good bacteria that help to protect the body from disease-causing bacteria

-Bifido-bacterial and lacto-bacilli are two types of bacteria that are considered important to our health. -Probiotics are foods that contain these bacteria. Fermented milk and yogurt are examples of probiotics that improve gut health and digestion. -Prebiotics refers to substances that stimulate bacterial growth in the large intestine.

Carbohydrates and Your Health

-Glucose regulation is important for your health. Both during and immediately after eating a meal, blood glucose levels begin to rise. Alternatively, during periods of fasting or simply in between meals, blood glucose levels may steadily decline. Nutritionists suggest the optimal blood glucose (or blood sugar) levels are between 70 and 100 mg/dl, and the body regulates these levels by using two main hormones: insulin and glucagon. -As levels rise, insulin is produced by the pancreas and then released into the blood. High blood sugar levels are referred to as hyperglycemia. Upon the release of insulin, two main actions occur: (1) the liver takes up glucose from the blood and stores it as glycogen and (2) muscles, adipose tissue, and various cells absorb the glucose into their cells. The resulting effect is that blood sugar levels are returned to within the acceptable (normal) range. -As levels decline, glucagon is released from the pancreas. Most often occurring if a person has not eaten for several hours, low blood sugar levels are referred to as hypoglycemia. In order to raise the level of blood sugar back to the acceptable range, glucagon coverts glycogen stored in the liver to glucose. Note: If there is an imbalance of either hormone (insulin or glucagon), the regulation of blood sugars levels would be lost.

Fats and your health (fats)

-HDL and LDL are often referred to as good cholesterol and bad cholesterol, respectively. High levels of LDL (or low levels of HDL) are linked to an increased risk of cardiovascular disease. High levels of LDL can lead to plaque formation in the arteries, a condition called atherosclerosis. Plaque inhibits proper blood flow through the arteries resulting in high blood pressure and the potential for a stroke or heart attack. By consuming a diet low in saturated fat, trans fat, and cholesterol, but high in fiber and omega 3 fatty acids, you can lower your LDL levels. -Note: Smoking cessation, exercise, weight management, and blood pressure control can also lower your risk for cardiovascular disease. High levels of HDL are also desirable in preventing heart disease.

Complex Carbohydrates (aka Complex CHO)

-Often referred to as polysaccharides, complex carbohydrates are made up of many glucose units joined together. -Examples of polysaccharides include starch, glycogen, and fiber. Plants store carbohydrates such as starch; sources include vegetables, beans, breads, pasta, and rice. Glycogen, as stated above, is the storage form of glucose, and it can be stored in the liver or muscle.

Proteins and your health(proteins)

-Protein can be derived from both animal and plant products. As such, the quality of protein can be divided into two categories: -High-quality(complete) protein comes from animals. All the essential amino acids are provided and can be used efficiently by the body. -Low-quality (incomplete) protein comes from plants, with a few exceptions. Example of plant foods that are considered complete protein include soy, buckwheat and quinoa. As the name implies, incomplete protein lacks one or more of the essential amino acids. When only low-quality protein foods are eaten, it is important to carefully plan your meals. In order to obtain a sufficient amount of all nine essential amino acids, multiple sources of protein should be used to complement these deficiencies. The process of consuming two incomplete proteins to make a complete protein is called complementary proteins. -Healthy Tip: Good sources of protein can be found within the dairy, meat, and bean groups. Notably, nuts, seeds, and legumes also fall into the meat and bean group—not only are they good sources of protein, but they also are low in fat and high in fiber, vitamins, and minerals. Conversely, grains and vegetables contain only a small amount of protein, while fruits have very little.

Protein Composition (proteins)

-Structurally, every protein is comprised of chains of amino acids. -Amino acids are the building blocks of protein and are formed mostly of carbon, oxygen, hydrogen, and nitrogen -In total, there are 20 different types of amino acids, and your body needs each one in order to function. Eleven of these are considered nonessential amino acids because our body can manufacture them from existing matter. The other nine are classified as essential amino acids because we must consume them in our diets as our bodies cannot naturally synthesize them. -In order to form into a protein, the chains of amino acids are held together by peptide bonds. The order and combination (also known as the sequence) of the amino acid chain determines the shape of each protein, and, in turn, the shape determines the function. Conversely, heat, enzymes, acid, or agitation can disrupt the normal protein structure (shape) and its function. Denaturation is the process of disrupting and destroying a protein's structure.

Mouth (beginning of the GI tract)

-The function of the mouth is to alter the food particles to prepare them to be swallowed. As previously described, both mechanical and chemical digestions take place in the mouth. Mechanical digestion occurs as the teeth break the food into smaller particles. The salivary glands are then stimulated to secrete saliva. Saliva is not an entzyme, but contains enzymes. Saliva is a watery fluid containing the lubricant (mucus) and (2) enzymes to prepare food for the next step in the GI tract. -Mucus mixes with food, lubricating the particles and making it easier to swallow -Enzymes released in the mouth have specific functions: • Salivary amylase breaks down starches. • Lingual lipase breaks down fats. -As an important component of the mouth, the tongue gives us the ability to taste food. The taste buds on the tongue provide the pleasure sensation we experience when we eat. There are five flavors that can be identified: 1 - sweet 2 - salty 3 - sour 4 - bitter 5 - umami (a meaty flavor)

The small intestine has several organs that guide giestion

-The liver secretes bile, which is stored in the gallbladder. -The gallbladder will store the bile until it receives a hormonal signal that fat has entered the small intestine. When this occurs, bile is released into the duodenum through the common bile duct. The bile begins to emulsify (break down) the fat into smaller pieces that can be mixed with water. -The pancreas releases a mixture of bicarbonate, enzymes, and water called pancreatic juice that breaks down carbohydrates, protein, and fats. The bicarbonate neutralizes the acidity of the chyme to protect the intestinal wall. Without the bicarbonate, the high level of acid would destroy the lining of the small intestine, resulting in the formation of an ulcer. -Glucagon and insulin are hormones also released by the pancreas to help with glucose regulation. -The ileocecal sphincter connects the small intestines to the large intestines. The role of the ileocecal sphincter is to prevent the contents of the large intestine from reentering the small intestine. Since undigested food cannot be absorbed in the small intestine, it must pass through the ileocecal sphincter and into the large intestine (also called the colon).

Carbohydrate Functions

-The main function of CHO (ultimately in the form of glucose) is to provide calories to the body as a source of fuel. -Remember carbohydrates provide 4 kcal of energy/gram. Muscles and red blood cells both rely on glucose as their sole source of fuel. -While the brain and central nervous system prefer glucose for energy, in the event that glucose is unavailable, both the brain and CNS can use ketones, a product of fat breakdown, as its source of fuel.

Digestion and Absorption (fats)

-The small intestine is the primary site for digestion and absorption of fats. However, digestion of triglycerides also occurs. Lipase is a fat digesting enzyme produced by both the salivary glands and the stomach that begins the initial digestion of fat. The gallbladder also aids in the digestive process of fats by secreting bile thereby further digesting fat and emulsifying it for absorption. -During the digestive process, the pancreas also secretes lipase to further aid in lipid digestion. Triglycerides, which are suspended in watery juices, are broken down into monoglycerides and fatty acids. These byproducts are then absorbed through the intestinal wall. After absorption, they are often later reformed into triglycerides as a means of storage. However, in order for fats to travel through blood and lymph to get to various cells within the body, lipoproteins are required.

Carbohydrates (CHO)

-are comprised of carbon, hydrogen, and oxygen molecules and, as we learned earlier (see Module 1), provide 4kcal/gram. Much of the world relies on carbohydrate-rich plant foods for their daily sustenance. -Carbohydrates are a major source of energy for cells, especially the brain, nervous system, and red blood cells. -Carbohydrates are available in the form of blood glucose or glycogen, a storage form of glucose. Glycogen is stored in the muscle or liver and helps to maintain blood glucose levels. -When levels begin to decline in the blood, glycogen is converted to glucose. CHO can be classified as either simple or complex (see below for more details).

Trans unsaturated fatty acids (trans fat)

-are found in food products such as stick margarine, shortening, and deep-fried foods. Trans fats are a type of partially hydrogenated unsaturated fat that is largely a byproduct of the food industry. Food scientists begin with an unsaturated fatty acid and (ultimately) convert it into a saturated fatty acid. Through a process called hydrogenation, hydrogen atoms are added to an unsaturated fatty acid, which breaks the existing carbon-carbon double bonds, producing a chain of singly bonded carbons surrounded by hydrogens—a saturated fatty acid. Thus, a complete hydrogenation reaction effectively makes a liquid (unsaturated) fat into a solid (saturated) fat. However, not all hydrogenation reactions are complete. An incomplete reaction produces partially hydrogenated fats, which, as described above, become known as trans unsaturated fatty acids. -Saturated fats as well as trans fatty acids can have negative health risks. In fact, trans fatty acids were recently determined to have a significantly higher impact on raising cholesterol levels than saturated fats. Importantly, foods can contain varying amounts of the different types of fatty acids. Fats in foods are therefore classified based on which fatty acid is present in the highest concentration.

Triglycerides (fats)

-are the major form of fats in our body and in our diet. A triglyceride is formed when three fatty acids bond together with a glycerol molecule -Functionally, triglycerides are a potential source of energy (including a stored form of energy in adipose tissue), can provide insulation and protection, serve as a carrier of fat soluble vitamins, and they can improve the taste of food. Triglycerides. The general structure of a triglyceride consists of a glycerol bonded with three fatty acid chains

Digestion and Absorption for proteins (proteins)

-cooking begins the digestive process by denaturing proteins, making the food easier to chew and swallow. In the stomach, enzymatic digestion continues the breakdown of protein through the release of pepsin, an enzyme produced by the stomach that further unravels (denatures) protein. -As described previously, when we think about or actually eat food, the hormone gastrin is released. Once released into the stomach, gastrin activates pepsin and digestion continues further. -The partially digested proteins then move from the stomach into the small intestine. The hormone cholecystokinin (CCK) is released in the small intestine, travels to the pancreas, and causes the release of trypsin, an enzyme that breaks the chains of amino acids into smaller units. Trypsin plays a vital role in the absorption process, as proteins are usually too big to be directly absorbed by the small intestine. Once broken down into smaller units, the amino acids are then absorbed into the portal vein, transported to the liver, and enter the overall circulation of the bloodstream. In the event of excess protein, the body can convert protein into fat for long-term storage.

Protein-calorie malnutrition (proteins)

-occurs when an inadequate intake of protein and calories over a period of time leads to muscle wasting and an increased risk of infection due to a compromised immune system. In developed countries, it is usually linked to alcohol/substance abuse or long-term hospitalizations. In developing nations, malnutrition is linked to a poor diet or inadequate intake of complete proteins. In children, protein-calorie malnutrition can be classified as either Kwashiorkor or Marasmus. -Kwashiorkor is defined as a severe protein deficiency as well as moderate energy or calorie deficiencies. -Marasmus is defined by severe deficiencies in both calories and protein.

GI tract tract is divided into 6 parts

1) mouth 2) esophagus 3) stomach 4) small intestine 5) large intestine 6) rectum

Four main organs produce and secrete substances that aid in digestion, but they are not part of the GI tract:

1) salivary glands 2) liver 3) gallbladder 4) pancreas

(absorption) There are three processes the body can use to move nutrients from the GI tract into the blood/lymph system and eventually into the cells:

1. Passive diffusion: Substances move easily in and out of cells without the use of energy. Nutrients move from high to low concentrations. 2. Facilitated diffusion: No energy is required, but a special protein carrier is required to help substances cross in or out of the cell. Nutrients move from high to low concentrations. 3. Active transport: Energy (ATP) is required to move substances in or out of the cell. Nutrients move from low to high concentrations.

Fruits, vegetables, breads, pasta, and dairy products all naturally contain carbohydrates, but they are also good sources of nutrients. Honey, jams, jelly, table sugar, soda, and desserts are also sources of carbohydrates. However, the latter examples tend to be high in calories and low in nutritional value. Dried beans, peas, and whole grains (often used to make cereal and bread) are good sources of starches.-

As a rule of thumb: Foods that are often high in starch are also good sources of fiber. Choosing foods that are (1) high in fiber, (2) whole grains, (3) fruits, and (4) vegetables can lead to a healthier life.

2.3 Macronutrients:

Carobhydrates

Constipation (malfunction of GI tract)

Constipation is when stools (feces) are hard, dry, and infrequent, and it is a result of slow movement through the large intestine. A change in diet and/or a review of medications can often alleviate the problem. Medications that are problematic include calcium and iron. People can make some dietary changes that will make their bowel habits more frequent and regular. Eating high fiber foods, such as whole grains, dried and fresh fruits and vegetables, and nuts, will stimulate the large intestinal muscles. -Note: As fiber is increased, the amount of liquids consumed should also increase. This will help to form a bulky, soft stool. Without the liquid, people may experience gas or flatulence.

Diverticulosis (malfunction of GI tract)

Diverticulosis is a condition that develops as we age. Small pouches form in weak spots in the colon, but it causes no problems in the majority of people. At times, food particles will get stuck in these pouches, resulting in an inflammation or infection called diverticulitis. The major cause of diverticulosis is a low fiber diet, which causes straining when passing stools. Increasing your fiber intake may reduce the symptoms and prevent diverticulitis from developing. Diverticulitis - starts when you see the symptoms starting to occur

Three sections of the small intestine

Duodenum: the first portion of the small intestine and widest Jejunum: the middle section Ileum: the final section that connects the small intestine to the large intestine

Protein functions (proteins)

Every cell contains a vast array of proteins, all of which must maintain proper shape to ensure proper function. In order to maintain optimal function, proteins are constantly being broken down and repaired—a process known as protein turnover. The many crucial functions of protein are outlined below: 1. Body structure: Muscles, connective tissue, mucus, hair, skin and nails are all comprised of protein. 2. Maintaining fluid balance: Blood proteins attract fluid, thus preventing swelling 3. Contribute to acid base balance: Proteins act as buffers to maintain proper pH. 4. Makes up hormones and enzymes needed to regulate body processes and catalyze reactions. 5. Contribute to immune function: Proteins form antibodies that attack bacteria and viruses. 6. Provide energy and satiety: Used for energy during exercise and calorie restriction.

Fats and Your Health

Fat can be found in many food sources. Saturated fats are found mainly in animal sources such as meat dairy products. Plants are the primary source of unsaturated fats mostly found in oils and nuts. When choosing packaged foods, it is important to read labels to determine the amount and kind of fat that is contained in each product. The following lifestyle recommendations are also provided to prevent cardiovascular disease: 1. Maintain a healthy weight.2. Eat a diet high in fruits and vegetables.3. Increase intake of whole grains and high fiber foods.4. Limit foods and drinks with added sugars.5. Prepare foods with little or no salt.6. If you consume alcohol, do so in moderation. By making wise food choices based on recommendations from the Dietary Guidelines, MyPlate, and the American Heart Association, we can enjoy healthy food and a healthy lifestyle.

2.5 Macronutrients

Fats

Trans fats

Food manufacturers also use a variety of fats for the purposes of taste, flavor, and satiety, as emulsifiers and to prevent certain fats from becoming rancid. Lecithin, a phospholipid, is used as an emulsifier in salad dressing to keep the fats and water from separating. Rancidity occurs when the double bonds in unsaturated fats begin to break down due to prolonged exposure to light and oxygen. Foods then take on an unpleasant flavor and odor. To prevent this, manufacturers often add trans fats to products. Forexample, crackers, cakes, and pies often contain trans fats to prevent rancidity. As you can see, fats can be hidden in almost any product. Reading labels and avoiding products that list partially hydrogenated fats as one of the first three ingredients is a good step towards limiting the amount of trans fat in your diet.

Glucose (a monosaccaride)

Glucose is often referred to as blood sugar. Much of the glucose in our diet is a result of the breakdown of starches and other sugars. By the end of the digestive process, almost all carbohydrates (CHO) are converted to glucose.

Heartburn (malfunction of GI tract)

Heartburn - known as acid reflux which happens whenever the stomach acids start to come up from the stomach into the esophagus. And people start to experience a burning sensation and nausea or gagging. For somebody who experiences this several times a week they would have something called GERD. The primary cause is the esophageal sphincter. If the esophageal sphincter is weak and relaxed, it does not close to prevent the stomach contents from traveling back into the esophagus. There are a few dietary treatments, including eating smaller meals that are low in fat, chewing food well, avoiding overeating, and limiting coffee & alcohol. In addition, nutritionists recommend waiting two hours after a meal before lying down and sleeping with the head of the bed elevated.

Protein functions cont. (proteins)

How much protein do we require daily? Most adults require 0.8 grams of protein per kg of body weight. During certain stages in the life cycle needs will be higher, such as pregnancy, growth, or after an illness. The goal for good health is to balance our protein intake with our daily loss. -Protein equilibrium describes a state when protein intake is equivalent to the amount of protein lost. In most cases, healthy adults achieve this balance. -Positive protein balance occurs when we take in more protein than we lose. Examples of someone in this state would be a pregnant mom, a growing child or teenager, or someone recovering from an illness. -Anabolic state is used to indicate that growth is occurring and muscle is being built. -Negative protein balance occurs when protein loss is greater than intake. This may occur during an illness or fasting, due to a trauma such as an accident or burn, or inadequate calorie intake. Muscle wasting and loss of body mass is usually the result. -Catabolic state is used to indicate that a loss or breakdown of muscle is occurring. -Note: To meet our protein needs, current recommendations are that 10-35% of our calorie intake should come from protein. (As a dietitian counseling healthy individuals, I often recommend that 10-15% of our calories should come from protein.)

Fats

In addition to heart disease, metabolic syndrome and certain cancers have also been linked to high fat diets. Metabolic syndrome is a cluster of symptoms that include, excess abdominal fat, high blood glucose levels, high triglycerides, low levels of HDL, and hypertension. If a person has three or more of these symptoms, they are diagnosed with metabolic syndrome, which is sometimes called Syndrome X. Their risk of mortality increases related to diabetes, obesity, and cardiovascular disease.

Fiber, another form of complex CHO, is different than starch because it cannot be digested. There are three types of fiber:

Insoluble (non-fermentable) -Does not dissolve in water -Not broken down by intestinal bacteria -increases stool speed passage through the large intestine Soluble (viscous) -Dissolves in water -Broken down by intestinal bacteria -Slows glucose absorption and can lower cholesterol -Provides satiety to a meal Functional - -fiber that is added to a product -Promotes intestinal health

Large intestine (last section of the digestive tract)

Large intestine) -(the last section of the digestive tract): It is five feet long and known as the colon. -It is divided into four sections: (1) ascending colon, (2) transverse colon, (3) descending colon, and (4) sigmoid. Relative to the small intestine, the large intestine does not play a major role in the digestion and absorption of nutrients. However, after leaving the small intestines, the remaining water and certain minerals (sodium, potassium, and chloride) can be absorbed in the large intestine. As the food waste passes through the large intestine, a semi-solid mass known as feces is produced. Feces remains in the rectum—the end portion of the large intestine—until muscular contractions push it into the anus to be expelled. The expulsion of feces from the body is controlled by two anal sphincters. -Within the colon, there are also many mucus-producing cells, the function of which is two-fold: First, the mucus holds the feces together. Second, the secreted mucus protects the intestine from bacteria. The bacteria in the colon are necessary for breaking down the remaining food products that entered from the small intestine as well as for breaking down of some forms of fiber.

Fat Functions

Lipoproteins are lipids surrounded by a shell of protein, phospholipids, and cholesterol. This coating allows the fats to be transported in watery substances, such as blood to tissue and cells. Four types of lipoproteins include: 1. Chylomicrons: is made in the small intestine. It transports dietary fat from the intestine to the cells. It also transports dietary cholesterol to the liver 2. VLDL is made in the liver. It delivers lipids to the cells. 3. LDL: Are remnants of VLDL that forms in the blood as VLDL loses its trglyceride content. It delivers cholesterol to cells 4. HDL: is mostly made in the liver, but sometimes made in the small intestine. It is a cholesterol "scavenger" that picks-up cholesterol from cells and tissue. HDL brings cholesterol back to the liver so that it can be excreted Figure 2.13. Lipoproteins. As an essential component for the absorption and transport of fats in the body, there are four types: chylomicron, VLDL, LDL, and HDL.

2.2 Digestive Disorders

Malfunctions of the GI Tract

The wall of the small intestine also has specialized enzymes that break down the disaccharides to monosaccharides:

Maltase digests maltose and the results are two glucose units. Sucrase digests sucrose and yields glucose and fructose. Lactase digests lactose to produce glucose and galactose. Note: Some individuals either lack the ability to produce lactase or make limited amounts, either of which results in an inability to effectively break down lactose. Symptoms include bloating and abdominal gas formation after ingestion of dairy products. The condition is referred to as lactose intolerance. Most individuals with this condition can tolerate cheese and yogurt and a small amount of milk.

Maltose (a disaccharide)

Maltose is a disachharide, that's a combination of glucose + glucose: It is rarely found in food. Maltose is used in the liquor industry to convert sugar to alcohol.

Monounsaturated fats (fats)

Monounsaturated fatty acids contain a single (mono) double bond between carbon atoms (C=C). Notice, two hydrogens are missing where the double bond (=) between the carbons are linked. Thus, the lipid chain is no longer considered saturated but is instead referred to as unsaturated. -Note: in unsaturated fats, there is at least one or more double bonds between carbon atoms Note: Liquid at room temperature, examples of monounsaturated fatty acids include canola and olive oils. Polyunsaturated fatty acids are classified as having two or more carbon-carbon double bonds. Thus, as the number of double bonds increases, the number of hydrogen bonds must proportionally decrease. Note: Liquid at room temperature, examples polyunsaturated fatty acids include corn, soybean, and sunflower oils. Additional examples of polyunsaturated fatty acids include the popular omega 3 and omega 6 essential fatty acids. Omega 3 (alpha-linolenic acid) refers to the placement of the first carbon-carbon double bond in the fatty acid. As shown in Figure 2.11, this double bond is located on the third carbon from the left side, commonly referred to as the methyl (-CH3) end. Likewise, if the first double bond is located on the sixth carbon from the methyl end, the fatty acid is classified as omega 6 (linoleic acid). Note: Essential fatty acids cannot be made by the body and must be supplied by food. Sources of omega 3 fatty acids include: soybean, canola oil, flaxseed oil, salmon, tuna, and mackerel. Vegetable oils are good sources of omega 6 fatty acids. In terms of convenience, it is much easier to get the omega 6 rather than omega 3 fatty acids in our diets.

Most monosaccharides are actively absorbed, meaning a carrier protein as well as energy is required to absorb the nutrients from the small intestine into the cells. Fructose uses facilitated absorption (a carrier protein is required, but no energy is needed) to be absorbed by the cells. After absorption, the monosaccharides are transported to the liver and either released as glucose into the blood stream, stored as glycogen for later use, or used for fat production.

Note: Fat production only occurs if there is excess calorie and carbohydrate consumption.

2.4 Macronutrients

Protein

Types of vegetarian eating (proteins)

Semi-vegetarian: Consumption usually includes fish and poultry in their diet Lacto-ovo vegetarian: Consumption includes milk and eggs Lacto vegetarian: Consumption includes dairy products Pesco vegetarian: Consumption includes fish Vegan: Consumption of plant foods only. Fruitarian: Consumption of only fruits, nuts, honey, and vegetable oil. (This plan is not recommended as it leads to nutrient deficiences)

Small intestine (part of the GI tract)

Small intestine -Is approximately 20 ft long and connects the stomach to the large intestine. It is named the small intestine due to its small diameter. Importantly, the vast majority of all digestion and absorption of nutrients occurs here. -

American Heart Association

The American Heart Association recommends that Americans consume no more than 30% of their calories from fat, and the Food and Nutrition Board recommends a maximum of 35% of your calories from fat. 7% or less of total calories should come from saturated fats, less than 1% from trans fats, and cholesterol intake should be less than 300 mg per day.

As discussed previously, digestion of carbohydrates begins in the mouth. Salivary amylase begins to break down starch into disaccharides. In the stomach, the acidic environment deactivates the amylase and prevents further digestion. Most digestion occurs in the small intestine, and this is also true relative to carbohydrates.

The pancreas releases pancreatic amylase to break down the polysaccharides into mono and disaccharides.

Villi (Part of the small intestine)

The small intestine is lined with mucosa, and it is folded over many times. Within the folds are finger-like projections called villi. Villi help trap food, and they are necessary for the processes of digestion and absorption.

Stomach (part of the GI tract)

The stomach's role is to store, mix, dissolve, and continue the digestion of food. As a continuation of the chemical digestion that began in the mouth, food particles in the stomach are mixed with gastric juice and enzymes. The acid in the gastric juice prepares proteins for digestion and activates enzymes. -Pepsin is an enzyme that breaks down proteins.• -Gastric lipase is an enzyme that begins fat digestion. -Chyme is the resulting substance when food particles are mixed with stomach acids and enzymes. Chyme is a very watery mixture that slowly empties from the stomach into the small intestine, controlled by the pyloric sphincter. Depending on the size of the meal consumed, this process occurs over a period of one to four hours. -Gastrin is the hormone responsible for regulating acid concentration in the stomach. Gastrin is produced when we begin to think about eating foods as well as during the actual ingestion of food. In conjunction with gastrin, mucus is also secreted to protect the stomach from its high level of acidity. -Intrinsic factor is a vital glycoprotein produced in the stomach. In order for vitamin B-12 to be absorbed, intrinsic factor must be present. Another sphincter, known as the pyloric sphincter, controls the release of chyme into the small intestine.

The more restrictions in a plant-based diet, the more planning is needed to prevent nutrient deficiencies while ensuring proper growth. However, there are many health benefits that can be achieved by following a vegetarian diet. A vegetarian diet usually consists of a lowered fat, saturated fat, and cholesterol intake, while the intake of fiber is increased. Notably, reduced risk for heart disease, obesity, hypertension, and cancer are often associated with this type of diet.

To be successful while consuming plant-based diets the following recommendations should be followed: 1. Choose whole grains and unrefined foods. 2. Eat a variety of fruits and vegetables. As a rule of thumb, the more colors on your plate, the more nutrients you are likely to receive. 3. Choose low fat dairy products. 4. Eggs are an excellent protein source. 5. As B12 only occurs naturally in animal foods, choose a regular source of vitamin B12 and D either through fortified foods or supplements. 6. Eat a variety of foods. If one uses careful consideration and chooses foods wisely, one can meet protein needs and receive the benefits of a plant-based diet.

Fat Composition (fats)

Triglycerides are fats and oils and are composed of fatty acids. Fatty acids are the simplest form of fats, Fatty acids are a chain of carbons linked together and surrounded by hydrogen molecules. At one end of the chain is an acid group, and at the other a methyl group. At the most basic level fats can be divided into being either saturated or unsaturated. The type of fatty acid is dependent on the bonds that link the carbon units together. Saturated fatty acids have no double bonds. Unsaturated fatty acids have at least one double bond. There are three main types of unsaturated fatty acids, they are (1) mono-unsaturated, (2) poly-unsaturated, or (3) trans-unsaturated fatty. Saturated fatty acids are all single carbon-carbon bonds, and the carbons are surrounded by the maximum number of hydrogen molecules. In other words, the carbons are saturated with hydrogens. Note: Solid at room temperature, saturated fats are found primarily in animal foods.

Sterols (fats)

are a class of lipid that includes hormones (steroids) and cholesterol, the most common sterol. All all sterols (including cholesterol) have a different structure than either triglycerides or phospholipids in that there are no glycerol backbones. Cholesterol can also be found in the membranes of some cells and, it is necessary in the production of several hormones and bile acids. While cholesterol is only found in animal foods, we do not need to consume any in our diet as the liver makes all the cholesterol our body requires.

Ulcers or peptic ulcer

are sores that can occur in the stomach, lower esophagus, or small intestine. Ulcers can be caused by certain bacteria (i.e. H. Pylori), or even from medications such as NSAIDs that erode the protective mucus lining. Stress, smoking, and genetics also play a role in the development of an ulcer. Symptoms include a burning sensation in the stomach following a meal or at night, weight loss, nausea, vomiting, and loss of appetite. Aside from avoiding foods that increase the symptoms, diet changes are often subtle. Treatment is largely based on lifestyle changes and medical treatment.

Fats (lipids)

are the third macronutrient that provides energy. Lipids are a concentrated source of energy, providing 9 kcal/ gram—double what carbohydrates and proteins supply in terms of energy. While lipid is a chemical term that includes many different compounds, there is one characteristic they all share: Lipids do not easily dissolve in water. There are three primary types of lipids: triglycerides, phospholipids, and sterols. Each has a different role. Let's look more closely at each type of lipid (fat).

Proteins

are vital for body structure; they regulate body functions; play a role in fluid balance, hormone, and enzyme production; and provide fuel to cells. -Like carbohydrates, proteins also provide 4 kcal/gram of energy. -In most developed nations, diets are rich in protein. In underdeveloped countries, insufficient protein can be a concern. -Although the majority of our protein comes from animal sources, plants can also serve as a viable source of protein. As such, many underdeveloped countries depend upon a mainly vegetarian diet to meet their dietary protein requirements.

Circular and longitudinal muscles (absorption)

comprise the outer layers that function to mix and move food along the GI tract. Notably, circular bands of muscle are most often found where one part of the tract connects to another, serving as valves to control the flow of the food particles..

pyloric sphincter

connects the stomach to the small intestines. Its major role is to control the release of chyme into the small intestine.

Sucrose (a disaccharide)

is a combination of glucose + fructose: It is very sweet and is found in table sugar, and honey.

Lactose (a disaccharide)

is a combination ofglucose + galactose: known as the milk sugar

Fructose (a monosaccaride)

is also known as fruit sugar. It is the sweetest tasting sugar.

Diabetes

is an example of a disease caused by hormone imbalance. There are two types of diabetes: Type 1 and Type 2. In both cases, blood sugar levels are high, and there is a lack of insulin. In people diagnosed -In people diagnosed with Type 1 diabetes, the pancreas does not make any insulin. Symptoms include excessive thirst, excessive urination and hunger, weight loss, and ketosis. Treatment includes insulin therapy, diet changes, and exercise. -Type 2 is more prevalent and is linked with being overweight. The pancreas makes some insulin, but your body either becomes resistant to it does not produce enough to cover your needs. Diet changes, exercise, and oral medications are often used to treat Type 2 diabetes. A diet high in soluble fiber can also help with blood sugar control as well as better weight control, lower cholesterol levels, and improved bowel health -Excessive intake of simple carbohydrates and sugar can have a negative impact on your health. Sugar provides calories but no nutritive value. Obesity, type 2 diabetes, and dental caries (tooth decay/cavities) are all linked to excessive consumption. In fact, metabolic syndrome, or Syndrome X, has been linked to a diet high in refined carbohydrates. A person diagnosed with this disease must exhibit at least three of the following conditions: (1) obesity, (2) poor glucose control, (3) hypertension, (4) increased blood triglycerides, and (4) low HDL cholesterol levels. However, by choosing fiber rich fruits, vegetables, and whole grains, while limiting foods and beverages that are high in sugar, we can feel confident that we are making wise food choices..

mucosa (absorption)

is made of absorptive cells and glands. It's an intestinal wall that's the inner-most layer.

Peristalsis (digestion)

is part of the mechanical process and involves involuntary muscle contractions used to move food mixtures along the tract

Diarrhea (malfunction of GI tract)

is the opposite of constipation. It is characterized by loose, watery, and frequent stools. Diarrhea usually results from an infection or a disease. Treatment usually requires increased fluid consumption to prevent dehydration. A diet of broth or low fiber foods should be consumed.

Digestion

is the process of transforming food into basic nutrients that can be absorbed and used by the body.

Galactose (a monosaccaride)

is usually bound to glucose, and it is the primary sugar in milk.

GI tract (absorption)

is where nutrient absorption occurs. It's a long hollow tube consisting of several layers of tissue that begins with the mouth and ends with the anus

Mechanical and Chemical processes (digestion)

occur once food enters the mouth, and begins to break it down into smaller units. Mechanical process - begins with chewing Chemical process - involves enzymes that are proteins that catalyze or speed up chemical reactions. Like digestion, enzymes catalyze the chemical reactions required to break down food particles into smaller parts, preparing nutrients for absorption

Irritable bowel syndrome

often referred to as IBS, is not well understood and is more common in females than males. Symptoms include bloating, abdominal pain, cramps, diarrhea, and/or constipation. Certain foods aggravate the symptoms, including gas producing foods. Therapy includes frequent small meals, low fat meals, high fiber intake, and probiotics.

Phospholipids (fats)

play an important role in the formation of cell membranes, are used to transport lipoproteins, and also act as emulsifiers. Phospholipid, as the name implies, consists of two major components: (1) a phosphate group, also known as the head group, and (2) two fatty acid chains, also known as the tail group. The two components are linked together by a molecule of glycerol. Egg and soybeans are all good sources of phospholipids.

Before food enters the mouth, a variety of events include (digestion)

• cognition: thoughts about food • sound: hearing a description of the food • odor: smelling food stimulates a hunger response and influence its taste • appearance: seeing the food • taste: when food enters the mouth and how it feels

Disaccharides:

(di means two) are two monosaccharide units joined together. Examples include: sucrose, lactose, and maltose.

Monosaccharides (part of carbohydrates):

(mono meaning one) are simple sugars. The monosaccharides commonly found in food are glucose, fructose, and galactose.

Esophagus (part of the GI tract)

(the tube that connects the throat with the stomach): The role of the esophagus is to transport food to the stomach. During the swallowing process, food lands on a flap of tissue called the epiglottis. -The epiglottis folds down over the trachea, or wind pipe, during swallowing to prevent food from entering the trachea. Without this mechanism, food would accidentally enter the trachea, resulting in choking. Once in the esophagus, the nervous system sends signals to the surrounding muscles in the GI tract to initiate peristalsis, which propels the food forward. -The sphincter muscle is a circular muscle located at the end of the esophagus. Once food passes through it on the way to the stomach, the muscle closes and prevents the backflow of the stomach contents into the esophagus.