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WageningenX: NUTR101x Nutrition and Health: Macronutrients and Overnutrition

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Module 1 - Basic Principles of Nutritional Science

24h recall: Method in which people are asked to recall all the foods (and amounts) they ate over the past 24 hours.
Confounding: Another factor other than the measured risk factor could be involved.
Dietary assessment: Retrieving information about a subject’s diet.
Dietary assessment – recall: Retrieving information about what people ate over the past 24 hours, written down by dietitian. Often done several times to get an estimation of peoples’ regular food consumption.
Dietary assessment – Food diary/record: People writing down their own diet, which is accurate if done well, but also time consuming and expensive.
Food composition tables: A way to convert information from the food questionnaires and food records into nutrition intake.
Food Frequency Questionnaire (FFQ): A long questionnaire that asks all kinds of questions about people’s dietary intake. It’s different between countries.
Recall bias: Happens when there are systematic differences between the cases and controls in the way they remember or report their dietary intake.
Reverse causality: The exposure could be the consequence of the outcome, instead of the other way around (main limitation in cross-sectional studies).
Selection bias: The fact that different groups in a certain study have very different backgrounds, resulting in different outcomes.
Self-reported Dietary assessment: Participants report their dietary intake themselves.
Study method – Case control: Dietary intake of a group of people with a certain disease (the controls) is compared to the dietary intake of a group of healthy people (the controls). The study looks back retrospectively (back in time) to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the risk factor and the disease.
Study method – Cohort: Participants report their dietary habits at the beginning of the study and are followed over time.
Study method – Cross-sectional: Observational study in which dietary intake and the outcome are assessed at the same time.
Study method – Ecological: Type of observational study in which the units of analysis are populations or groups of people. Looks at existing data.
Study method - Experimental study: Study where researchers introduce an intervention (in people’s lives) and study the effects.
Study method – Intervention: Researchers change something, they intervene. See experimental study.
Study method – Observational study: Type of study in which individuals are observed or certain outcomes are measured. No factors are changed.
Study method – Prospective study: People are studied over time.
Study method – Retrospective study: A study that looks back in time.

Module 2 - Carbohydrates

Amylase: An enzyme that breaks down starch. Is inactivated by the acidity of the stomach.
ATP: The major energy currency molecule that fuels almost all energy-consuming processes in cells and tissues, such as transport and synthesis of molecules, muscle contraction, and nerve transmission.
Blood sugar: Glucose in the blood.
Bicarbonate: Present in pancreatic juices, raising the pH towards neutrality in the duodenum. Pancreatic juice is also rich in pancreatic amylase, which is responsible for most of the starch digestion.
Carbohydrates: Also called sugars and they are the most important macronutrient. They conform to the chemical formula (CH2O)n. There is a division between simple and complex carbohydrates. The energy content of 1 gram of carbohydrate is 4 kcal or 17 kJoules.
Cellulose: A linear chain of glucose, similar to amylose, except that the glucose units are linked in such a way that our digestive enzymes cannot break them. As a result, it leaves the human body completely undigested.
Complex carbohydrates: Polysaccharides. There are three main groups: glycogen, starches and fibers.
Dietary fiber: Dietary carbohydrates that are not subject to digestion by endogenous enzymes, but may be digested by bacteria in the colon. They are classified in soluble and non-soluble fiber.
Disaccharides : Linkage of two monosaccharides. There’s maltose, sucrose and lactose.
Enterocytes: Intestinal cells which take up the macronutrients.
Fermentation: Soluble fibers can be fermented in the colon by gut bacteria, producing short chain fatty acids (SCFA) and gases. The SCFA (acetate, propionate, and butyrate) are absorbed by the cells lining the colon and can be used for energy.
Fructans: Polymers of fructose. The best known representatives are the highly fermentable inulins. Inulin is naturally present in various foods, such as asparagus, leek, onions, and banana. In addition, inulin is added to foods as a functional pre-biotic food ingredient to confer a health benefit.
Fructose: An important component of both regular sugar and HFCS. It is processed entirely in the liver, providing plenty of substrate for fat synthesis (remember: fat can be made from carbs but not vice versa).
Glucagon: When blood glucose levels are low - as during fasting - the pancreas releases this. It stimulates the breakdown of glycogen stored in liver and thus helps to maintain blood sugar levels. 
Glucose oxidation: The process used to convert the energy present in glucose into a form that can be used by cells: ATP. Once taken up, glucose is first catabolized via glycolysis to form pyruvate, which is taken up into the mitochondria and converted into acetyl-CoA. Acetyl-CoA can be considered the biochemical “hub” of the cell. Acetyl-CoA is further oxidized via a biochemical pathway called the tricarboxylic acid (TCA) cycle or citric acid cycle. 
Glycogen: The animal equivalent of starch. It is produced when there is an excess of glucose present. It is a branched polymer of glucose stored in the cell in special structures called glycogen granules inside liver or skeletal muscle. The liver uses it to regulate blood sugar levels and the muscles to provide energy during strenuous exercise. When the cap of storage is reached, excess carbohydrates can be stored in the body as fat. 
Glycemic index: Describes the relative increase in blood glucose after consuming a particular food in comparison with a standard food. Foods that have a high GI cause a more pronounced increase in blood glucose, whereas foods with a low GI cause a shallow increase in blood glucose. 
High-fructose corn syrup: Mixture of glucose and fructose originating from corn. The amount of fructose is expressed in a number following the abbreviation HFCS. (Example: HFCS 55 contains 55% fructose and 45% glucose).
Hydrolysis: The breakdown of disaccharides into the individual monosaccharides. 
Insoluble fibers: Fiber that is not digested and fermented and leaves the body mostly intact. They add weight and volume to our stools. It includes cellulose, lignin, hemicellulose, resistant starches.
Insulin: The absorption of glucose after a meal will cause the blood glucose levels to go up. The increase in blood glucose triggers the pancreas to release this compound. It has two major actions: 1) it stimulates tissues such as muscle to take up glucose, 2) it stimulates the liver and muscle to store glucose in the form of glycogen. The combined action leads to a reduction in blood glucose levels. 
Inverted sugar: A mixture of equal amounts of glucose and fructose. It is produced by enzymatic cleavage of sucrose into the two individual monosaccharides. It is a little bit sweeter than sucrose and has several (industrial) uses including in the production of alcoholic beverages. It is also utilized by food manufacturers to retard the crystallization of sugar and to retain moisture in the packaged food. Honey is a natural form of this compound. 
Lactase: Cleaves lactose into glucose and galactose. 
Lignins: Unlike other dietary fibers, this does belong to the carbohydrates. They are complex polymers of aromatic alcohols. It is the second most abundant natural polymer in the world, next to cellulose. 
Maltase: Breaks down maltose into glucose. It is produces by enterocytes.
Monosaccharides: Building blocks of carbohydrates. Glucose, fructose and galactose. 
Pectin: Part of the cell wall of plants. Its key feature is the abundant presence of galacturonic acid. It is often added during food manufacturing to impart gelation, viscosity, texture and protein stability. 
Resistant starches: Starches that are not subject to regular digestion in the GI tract. Depending on the type, they may be partially fermented in the colon by the gut microbiota. They can be divided into distinct groups. RS1: physically inaccessible starch (coarsely ground or whole kernel grains), RS2: granular starch (uncooked potato, unripe banana flour), RS3: retrograded starch (cooked and cooled starchy foods), RS4: chemically modified starches.
Salivary glands: Produce a special enzyme called amylase that is able to break down starch. This enzyme gets inactivated by the acid environment of the stomach. 
Simple carbohydrates: The monosaccharides and disaccharides. Mono-saccharides consist of glucose (blood sugar), fructose and galactose and can be directly absorbed into our bloodstream. Di-saccharides consist of maltose (product of starch digestion in the intestine) (glucose + glucose), sucrose (table sugar) (glucose + fructose) and lactose (“milk sugar”) (glucose + galactose) for which hydrolysis is needed to break them down to mono-saccharides before they can be digested. 
Soluble fibers: Fiber which attracts water and turns into gel during digestion. Soluble fibers are present in plant foods such as whole-grains, fruits, legumes, seeds and husks, and vegetables. Processing of these foods usually leads to a significant reduction in their fiber content. Dietary fibers are highly abundant in the plant cell wall. It includes pectin, hemicellulose and fructans. 
Starch: A polymer of glucose. The most consumed source of carbohydrates. Consist of amylopectin (branched chain of glucose molecules) and amylose (linear chain of glucose molecules), i.e. in bread, rice and corn, they all have different conformations. 
Sucrase: Cleaves sucrose into glucose and fructose.
Sugar: Table sugar (sucrose). 
TCA cycle: The energy liberated during glycolysis and this process is temporarily stored in a molecule called NADH, for nicotinamide adenine dinucleotide. NADH donates its energy to a set of proteins that together comprise the electron transport chain and which ultimately converts the energy into ATP.

Module 3 - Carbohydrates and Health

Added sugar: Mono- and disaccharides added to food and drinks during manufacturing of preparation. FDA’s definition: sugars that are either added during the processing of foods, or are packaged as such, and include sugars (free, mono- and disaccharides), sugars from syrups and honey, and sugars from concentrated fruit or vegetable juices that are in excess of what would be expected from the same volume of 100 percent fruit or vegetable juice of the same type.
Cross-over design: Experimental study in which every subject follows both diets.
Diabetes type 1: Is an auto-immune disorder. Usually starts during childhood or adolescence. It develops because for some unknown reason the body’s immune systems destroys the cells that produce insulin. These so called beta-cells are located in special structures called islets of Langerhans in the pancreas. Because the body is unable to produce insulin itself, patients need daily injections of insulin to control their blood glucose levels.
Diabetes type 2: Insulin resistance/insensitivity. Usually starts at older age and is most often coupled to obesity. As people develop obesity, the ability of their tissues to respond to insulin progressively declines.
Empty calorie foods: Foods that are rich in energy but are relatively devoid of other nutrients and thus carry little nutritional value.
Free sugars: Term made up by the WHO. Refers to all monosaccharides and disaccharides added to foods by the manufacturer, cook or consumer, plus the sugars that are naturally present in honey, syrups and fruit juices.
High intensity sweeteners: See non-nutritive sweeteners.
Lactose intolerance: Being intolerant to the effects of lactose in the diet. There’s a deficiency of the enzyme lactase.
Non-nutritive sweeteners: They are artificial and extremely sweet (expressed per weight). They are used in very small quantities in foods and therefore contribute very little to no energy to the food. The best-known non-nutritive sweetener is aspartame.
Nutritive sweeteners: Also referred to as sugar alcohols and bulk sweeteners. They are often confused with non-nutritive sweeteners. However, in contrast to non-nutritive sweeteners, their relative sweetness is lower than that of sugar.
Parallel design: Experimental study where one group of subjects follows one diet and another group follows the other diet.
Sugar alcohols: See nutritive sweeteners.

Module 4 - Lipids

∆-designation: nomenclature of a fatty acid: 18:2∆9 (18 = number of carbon atoms, 2 = number of double bonds, 9 = place first double bond counting from carboxylene) 
Adipocytes: Fat cells that contain 1 large lipid droplet and regulate LPL activity.
Adipose tissue: Tissue that functions as heat insulator, energy storage depot and produces hormones.
Beta-oxidation: The fatty acid is progressively shortened to yield Acetyl-CoA. This step is called beta-oxidation. This is the first step of the burning of fatty acids.
Bile acids: Fat digestion relies on the presence of a set of compounds that we call bile acids and these bile acids play an important role in fat digestion by functioning as emulsifiers. Bile acids are produced in liver from cholesterol and stored together with cholesterol and phospholipids in the gallbladder.
Brown fat: Fat cells that are activated by cold and produce heat = cold-induced thermogenesis.
Cis-configuration: Double bonds within unsaturated fatty acids. The adjacent hydrogen atoms are on the same side of the double bond: kink in the chain.
Cholecystokinin (CCK): Hormone produced by the small intestine that causes the gallbladder to contract and release its content into the duodenum.
Cholesterol: Cholesterol is not a nutrient because our own cells can make cholesterol. Only approximately one-third of the cholesterol in our bodies comes from our diet. For this reason, we can subsist on a diet that is completely devoid of cholesterol. Cholesterol has a number of functions in the body: it is needed to make bile acids, used to make several (steroid) hormones and the synthesis of vitamin D and it is a component of cell membranes. Cholesterol needs to be packaged into special particles (HDL or LDL) because it is a lipid and thus not soluble in water.
Chylomicron remnant: Remnant of chylomicron which is mostly devoid of triglycerides.
Chylomicrons: Specialised particles that transport triglycerides throughout the bloodstream. They are coated with a thin layer of protein in order to be able to transport the fat throughout the bloodstream.
Cold-induced thermogenesis: Tissue is able to produce heat. Happens with brown fat, that exists in certain mammals.
Delta designation: Nomenclature of the fatty acids: denote the carbon chain length, followed by the number of double bonds: Counts from the carboxylene and indicates the position of all double bonds.
Docosahexaenoic acid (DHA): Essential fatty acid (phospholipid) that plays an essential role in the brain and retina.
Duodenum: First part of the small intestine where preparation of food absorption begins.
Eicosapentaenoic acid (EPA): Essential fatty acid that plays a role in virtually every process in the human body.
Enterocytes: Cells of the small intestine that take up micelles and re-esterificate the fatty acids and mono-glycerides back into triglycerides.
Emulsifier: Helps mixing of oil and water to create a stable emulsion.
Essential fatty acids: Fatty acids that people can’t make themselves and need to get in through their diet: the linoleic acid and linolenic acid.
Fat-cell turnover: The fat cell is renewed, this happens after 10 years. The content of the fat cells is renewed much more quickly (6x).
Fatty acid: Chain of hydrogenated carbon atoms connected to a carboxyl group. The fatty acids that are part of the triglyceride molecule differ in three major properties: chain length, degree of unsaturation, point of saturation.
Fatty acid composition: Types of fatty acids present in a food.
Gallbladder: Organ that stores bile, cholesterol and phospholipids.
Gastric lipase: Enzyme produced by the stomach that breaks down lipids.
Hydrogenation: Process in which unsaturated fatty acids are converted into saturated fatty acids, by adding H-atoms. It is an industrial procedure that makes the fat less likely to spoil and bestows favourable sensory and textural properties.
Hyperplastic obesity: Form of obesity where the number of fat cells is too high.
Hypertrophic obesity: Form of obesity where the size of the fat cells is too high.
Lacteals: Small lymphatic vessels where chylomicrons are released.
Lingual lipase: Enzyme produced by the salivary glands that detects lipids.
Linoleic acid: C18:2 makes other fatty acids and fatty acid derivatives that play an essential role in the human body → arachidonic acid → eicosanoids → prostaglandins (pian, immune function, blood pressure regulation, blood clotting).
Linolenic acid: C18:3 Linolenic acid: Makes prostaglandins, EPA and DHA (fish oil).
Lipoproteins: Particles that carry fat in our blood: VLDL, LDL & HDL.
Lipoprotein lipase (LPL): Enzyme that hydrolyses triglycerides into mono-glycerides and fatty acids.
Low density lipoprotein (LDL): VLDL particle of which triglycerides are removed and transports cholesterol from liver to tissues that need it. LDL is a very important molecule because it has been very strongly linked to heart disease.
Lymphatic circulation: Complex system of fluid drainage, transport, immune response and disease resistance.
Micelles: special structure formed by bile acids and the fatty acids and mono-glycerides that are released upon digestion of dietary triglycerides.
Mono-glyceride: A molecule that consists of glycerol and 1 fatty acid.
N or omega designation: Nomenclature of the fatty acids: denote the carbon chain length, followed by the number of double bonds: Counts from the methylene and only indicates the position of the first double bond.
Pancreatic lipase: Enzyme that is mostly responsible for the dietary fat digestion. Pancreatic lipase is produced by the pancreas.
Phospholipids: The second lipid component of diet. Phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline. They have a polar side and an apolar side. This property is referred to as amphipathic. They are major components of all cell membranes.
Saturation: Number of double bonds.
Small intestine: Organ of G.I. tract in which most of the food absorption takes place.
Stearic acid: C18:0
Sterols: Lipids that play an essential role in cellular communication and metabolism and are present in plants and animals.
Total fat mass: Number of fat cells and the size of the individual fat cells.
Trans-configuration: Two hydrogen atoms are bound to opposite sides of the double bond: more linear.
Trans-fatty acids: Fatty acids in which the H-atoms at the double bond are on the opposite side.
Triglycerides: Dietary lipids consist of triglycerides (and phospholipids and sterols): Three fatty acids linked via a glycerol molecule.
Very low density lipoprotein (VLDL): This particle very much resembles the chylomicron particle. It is basically a tiny lipid droplet that is surrounded by a coat of protein. The very low density lipoprotein particle contains triglycerides and on top of that cholesterol similar to the chylomicron particle. It is processed primarily through the activity of lipoprotein lipase in the adipose tissue and the muscle. It is taken up into the adipose tissue and muscle as an energy source or to serve as a storage form of energy.

Module 5 - Lipids and Health

Adhesion molecules: The endothelium produces these sticky molecules. They capture the white blood cells.
Atherosclerosis: Process that is most often at the basis of heart disease. It is the build-up of plaque in the walls of arteries, leading to narrowing of the arteries and gradual obstruction of blood flow. It takes years to develop and happens insidiously without people noticing it (“asymptomatic”).
Blood coagulation: Activation, adhesion, and aggregation of platelets.
Cardiovascular disease (CVD): CVD is a class of diseases that involve the heart and/or the blood vessels. The most common form of cardiovascular disease is coronary heart disease (CHD)/ischemic heart disease.
Coronary heart disease (CHD): Disease in which the blood vessels providing blood to the heart muscle become narrow and rigid and restrict the blood flow to the heart.
DALY (Disability-adjusted life year): DALY is a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability or early death. One DALY represents one lost year of "healthy" life. The sum of these DALYs across the population, or the burden of disease, can be thought of as a measurement of the gap between current health status and an ideal health situation where the entire population lives to an advanced age, free of disease and disability.
Diastolic pressure: Is the pressure against the arteries as the heart relaxes and fills with blood. The normal diastolic pressure is usually between 70 and 80 mmHg.
Embolism: When a blood clot has traveled through your arteries and becomes stuck it is called an embolism.
Endothelium or intima: The inner layer of the normal artery. Is in direct contact with the blood.
Foam cells: White blood cells are moved inside the wall of the artery and they include T-cells and macrophages. In the vessel, macrophages take up lipid and become foam cells.
Fibrous cap: The lipid core is covered by a thick layer of materials typically found in connective tissue forming a fibrous cap. When a fibrous cap is broken down, it causes the plaque to become unstable and prone to rupture which triggers blood clotting (thrombosis).
Fractional cholesterol absorption: The proportion of cholesterol in the intestine that is absorbed into the body (varies from 30 to 80%).
Heart disease/cardiovascular disease: Diseases that involve the heart- and/or blood vessels.
High-density lipoprotein: Particles that are thought to pick up cholesterol from cells and tissues and deliver it back to the liver. Hypertension: High blood pressure.
Lipid or necrotic core: Central region of the plaque where cells die and cell debris including lipids accumulates.
Mono-unsaturated fatty acids (MUFA’s): Fatty acids that contain one double bond.
Personalized nutrition: How people respond to dietary changes individually.
Poly-unsaturated fatty acids (PUFA’s): Fatty acids that contain more than one double bond.
Primary prevention: Study the effect of something in subjects that never had, for example, a heart attack.
Saturated fatty acids (SFA’s): Fatty acids that do not contain double bonds.
Secondary prevention: Study the effect of something in subjects that already had, for example, a heart attack but survived.
Stroke: Occurs when the arteries supplying blood to the brain become blocked and blood flow is impaired.
Systolic blood pressure: Is the pressure against the arteries as the heart pumps. The normal systolic pressure is usually between 110 and 130 mmHg.
Thrombosis: The formation of a blood clot (thrombus) inside a blood vessel, obstructing the flow of blood. Blood clots form via the process of blood coagulation.
Trans fat: Killer fats, are abundant in things like frying oil, pastries, fast food, etc.

Module 6 - Proteins and Health

Amino acids: The building blocks of proteins. Containing both a carboxyl (—COOH) and an amino (—NH2) group.
Biological value (BV): is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the animal.
Carboxypeptidase and aminopeptidase: What these two enzymes do, is that they cleave off individual amino acids.
Digestion: The process of ‘cutting’ polypeptides into individual amino acids which happens in our GI tract. There is no digestion in the mouth.
Digestion – colon: The remains of the protein go into the colon and will leave the body undigested. This is about 5%.
Digestion – lower small intestine (downstream): Enzymes cutting the smaller peptides into individual amino acids.
Digestion – stomach: Acidity causes unfolding of proteins so enzymes have better access.
Digestion – upper small intestine (upstream): Enzymes are added that cut the chain to smaller peptides.
Dipeptide: Two amino acids linked.
Enzymes – lower small intestine (downstream): Carboxypeptidase and aminopeptidase.
Enzymes – stomach: Pepsin, produced by the chief cells lining the stomach and secreted as an inactive pro-enzyme called pepsinogen which is activated by the acid environment resulting in its self-cleavage to form pepsin.
Enzymes – upper small intestine (upstream): Trypsin and chymotrypsin.
Essential amino acids: amino acids that have to be a part of our diet.
Extracellular functions: Functions outside the cell, e.g. hormones.
Gluconeogenic amino acids: The carbon part of amino acids that can be converted into glucose.
Intracellular functions: Functions inside the cell, e.g. structure of the cell.
Ketogenic amino acids: The carbon part of the amino acids that cannot be converted into glucose.
Limiting amino acid: is the amino acid that is least abundant in a dietary protein source in comparison with the average human body protein.
Measures of protein quality – Biological value (BV): Based on the weight gain of an animal divided by its intake of a particular food protein during the test period. (Used to be the official method but was replaced by PDCAAS).
Measures of protein quality – Digestible Indispensable Amino Acid Score (DIAAS): Indigestibility is ascertained by measuring the proportion of a particular dietary protein that ends up in the stools. The proportion of a particular dietary amino acid that reaches the terminal ileum is measured. The rationale behind the change is that the relative absorption of a dietary protein is best captured by looking at how much of a dietary amino acid reaches the lower ileum as opposed to how much protein is in the stools because the stools also contain endogenous proteins such as digestive secretions, mucous cells and bacteria which are not derived from the diet. The protein quality score is determined by the lowest ratio of digestible indispensable amino acid content to the corresponding indispensable amino acid in the reference pattern. The lowest ratio will be obtained for the limiting amino acid in the protein.
Measures of protein quality – Protein Digestibility Corrected Amino Acid Score (PDCAAS): The Amino Acid Score (AAS) for any particular protein is calculated by comparing the level of the limiting amino acid in the protein in question to the level of the same amino acid in a reference protein. The PDCAAS is the AAS corrected for digestibility. Thus, the formula for calculating the PDCAAS is : The AAS x digestibility. AAS equals mg of limiting amino acid in 1 g of test protein/ mg of same amino acid in 1g of reference protein. The PDCAAS has a maximum value of 1.0 (or 100). Proteins having values higher than 1.0 are rounded off to 1.0. One of the advantages of PDCAAS is that it is relatively easy to calculate and it is based on human amino acid requirements.
Negative balance: Less protein enters the body than leaves the body.
Nitrogen balance: The balance between amino acid input via the diet (mostly from proteins) and the amino acid output via conversion to urea and loss via the urine. Non-essential amino acids don't have to be part of our diet, and can actually be synthesized from the essential amino acids in our diet.
Pepsin: breaks down dietary protein into smaller peptides, polypeptides. Peptide bonds: individual amino acids are linked together. Polypeptide: exists out of twenty different amino acids. 
Positive balance: More protein enters the body than leaves the body.
Protein: Building block. It consists out of polypeptides made out of amino acids. It is a macronutrient.
Protein balance = nitrogen balance: refers to the difference between how much protein goes into the body.
Protein complementation: Combining proteins to achieve a higher protein quality. 
Protein Efficiency Ratio (PER): is based on the weight gain of an animal divided by its intake of a particular food protein during the test period.
Protein functions – building material: Most structural and abundant protein in the body is collagen. Collagen acts like a scaffold that gives strength and structure to cells and tissues. Defects in collagen synthesis lead to osteogenesis imperfecta, which is characterized by very brittle bones that fracture easily.
Protein functions – antibodies: They circulate in the body and are involved in our immune defense. Also referred to as immunoglobulins and are secreted by plasma cells.
Protein functions – enzymes: They are proteins that speed up a biochemical reaction. Also called catalysts. Every cell has thousands of different enzymes responsible for different reactions.
Protein functions – exporters: They assist with the import or export of different molecules across the cell membrane.
Protein functions – hormones: They are the messengers that circulate in the blood. They are released from a particular tissue into the bloodstream to signal to distant tissues. Chemically, hormones are either polypeptides or steroids.
Protein functions – regulation of fluid balance: Proteins play an important role in making sure the water in the body is appropriately distributed across the bloodstream (intravascular compartment), the space between cells (intercellular compartment), and inside cells (intracellular compartment).
Protein turnover: The balance between protein synthesis and protein degradation.
Protein turnover rate: The time necessary for the protein to be degraded or synthesized.
Protein quality: Determined by two variables: digestibility and amino acid composition.
Recommended daily allowance (RDA) for dietary protein: 0.8 gr/kg of body weight/day.
Sarcopenia: Gradual decline in muscle mass and an increase in fat mass. A condition more common among the elderly.
Trypsin and chymotrypsin: They cleave the polypeptide chain at specific amino acid sequences.

Module 7 - Energy homeostasis and energy balance

Appetite: The integrated response to the sight, smell, thought or taste of food that triggers eating.
Atwater factors: Used for the calculation of the available energy of foods (carbohydrates 4 kcal/g, fat 9 kcal/g, protein 4 kcal/g).
BMR – Basal Metabolic Rate: Energy required for basal maintenance in the fasted state.
Bomb calorimeter: Special device used for calculating the gross energy by burning the food.
Calorimetry: Method to calculate energy expenditure estimates for exercise.
CCK (cholecystokinin): Satiety hormone.
Dietary-induced thermogenesis: Obligatory energy costs of digestion and absorptions. Around 10% of the energy in a meal.
Digestibility: The proportion that is absorbed, constant value for each macronutrient (carbohydrates 98%, fat 95%, protein 92%).
Digestible energy: The proportion of the energy that is absorbed in the body. (Carbs: 98%, fat: 95%, protein, 92%.)
Energy balance: The balance between gross energy intake and energy loss via stools, urine and expenditure.
Energy expenditure: Energy lost as energy burn.
Energy out 1: Energy expenditure (physical activity, maintenance, growth).
Energy out 2: The energy that leaves our body through feces, urine.
Food intake: Food you consume.
Ghrelin: Hunger hormone.
GLP-1 (glucagon-like peptide 1): Satiety hormone.
Gross energy: Includes all the energy in a food product.
Growth: Covers the net energy required to make extra tissue.
Hunger: The uncomfortable sensation caused by lack of food, that makes people look for food.
Hypothalamus: Part of the brain that receives short- and long-term signals, together with other stimuli (emotional, cognitive, hedonic). These stimuli influence hunger and appetite.
Insulin: Satiety hormone.
Kcal: an abbreviation for kilocalories, a unit for energy.
Leptin: Hormone produced by fat tissue, long term regulation of food intake. Lack of leptin causes hunger. A genetic defect causing a lack of leptin will lead to extreme hunger.
Long term feedback signals: Signals derived from adipose tissue and reflect the size of de adipose tissue stores.
Maintenance: Physiological processes that are essential for the survival of an individual such as heartbeat, brain function, respiration etc.
Metabolizable energy: The amount of energy that is left, the energy that is available for the body to use after taking into account the loss of dietary energy in stools and urine. This is also the energy content described on food packages.
Negative energy balance (= weight loss): Energy going out exceeds energy coming in.
Net energy: Remains of energy available for maintenance, physical activity and growth.
New equilibrium: Bodyweight doesn’t increase in a linear fashion, because energy expenditure increases upon weight gain due to a higher BMR. The energy cost of physical activity will be higher with a greater body weight. Thus, eating more results in weight gain, and weight gain results in an increased energy expenditure and thus a higher BMR.
PAL: Physical Activity Level total energy expenditure divided by the basal metabolic rate (very active > 2.0, extremely inactive < 1.4, normal 1.6-1.7)
PAR: Physical Activity Ratio describes the energy cost of an activity expressed as a multiple of basal metabolic rate (lying, sitting 1.0-1.4, walking 4, running >10).
Physiological factors: Factors like complicated feedback mechanisms in our body that lead to hunger sensation and food seeking behaviour when food intake and energy supplies drop.
Positive energy balance (= weight gain): Energy coming in exceeds the energy going out.
Psychological factors: Factors like stress (emotional eating).
Satiation: The feeling of satisfaction and fullness that occurs during a meal and that makes you stop eating. Determines how much food is consumed during a meal.
Satiety: The feeling of satisfaction that occurs after a meal and prevents you from eating until the next meal. Determines how much time passes between meals.
Sensory factors: The sensory properties of food (taste, smell, sight, sound).
Short term feedback signals: Signals that originate from the gastrointestinal tract and influence satiation and satiety.
Social factors: Cultural factors, social settings and celebrating special occasions determine our food intake.
Thermogenesis: Process of heat production in organisms.

Module 8 - Weight management

Adoption studies: Studies with adoptees. Studied if an adoptee’s BMI is more closely to the BMI of the adoptive parents or the BMI of the biological parents.
Bariatric surgery: Involves the removal of parts of the stomach and small intestine to induce weight loss.
Bioelectrical impedance: Test to determine the amount of bodyfat by sending tiny electrical impulses through the body and measuring the return of those impulses.
BMI (Body Mass Index): Used to classify people as overweight/obese, calculated by dividing the weight in kilograms by the square of the height in meters (20-25 is normal, > 30 is overweight, > 40 is obese).
Diabetes type 2: Illness (often occurs in overweight persons) in which the body becomes less sensitive to the effects of insulin (insulin resistance).
Dual energy X-ray absorptiometry: Test to determine the amount of bodyfat y using x-rays to determine body composition.
Environmental factors in obesity: Environmental factors that can contribute to obesity like easy access to foods, food commercials, food channels, processed foods, sedentary lifestyle.
Fatfold/skinfold tests: Method to determine bodyfat level. Measures the thickness of the skin. There is a correlation between the thickness of the fat layer (under the skin) and the total amount of bodyfat.
First law of thermodynamics: A person can lose bodyfat either by decreasing energy intake or increasing energy expenditure.
Genetic factors in obesity: Genetic causes of obesity. Refers to the fact that genetics have great influence on obesity. Genetics determine especially where the fat is stored, not how much fat is stored.
Hydrodensitometry (underwater weighing) and air displacement plethysmography: Test to determine the amount of bodyfat by measuring the volume of the body. An obese person has a low body density and thus will float in water, whereas a lean person has a high body density and will sink in water.
Hypocaloric diets: Diets that contain fewer calories (and less energy) than the combined foods normally consumed by a particular person.
Insulin insensitivity/resistance: The bodies of obese people are less sensitive to the effects of insulin.
Magnetic Resonance Imaging (MRI): Methods that can be used to see where the visceral and subcutaneous fat is located around the abdominal.
Metabolic syndrome: Syndrome in which a person has a number of metabolic abnormalities (abdominal obesity, elevated blood cholesterol & triglycerides, hypertension, insulin resistance).
Monotonous diets: A diet with one specific type of food. Often results in sensory-specific satiety and are very effective on the short-term.
Mortality: Risk of dying from any cause.
Obesity: A medical condition in which excess body fat has accumulated to an extent that it may have a negative effect on health.
Obesogenic environment: The combination of environmental factors contributing to obesity in individuals or populations.
Psychological factors in obesity: Psychological causes of obesity. Refers to comfort eating, emotional eating, eating when stressed/lonely or eating triggered by external cues (sight/smell of food).
Sensory-specific satiety: The declining satisfaction resulting from the consumption of one specific type of food.
Social factors in obesity: Social causes of obesity. Refers the social-economic status, social network and cluster influence obesity (the heavier your family is, the more likely it is that you’ll become heavy too) and social norms.
Subcutaneous fat: Body fat stored below the skin.
Twin adoption studies: Studies in which they compare the similarity in obesity between twins reared apart and twins reared together.
Twin studies: Studies that compare the similarity in obesity between two identical twins with the similarity between two non-identical twins.
Visceral fat: Body fat located within the abdominal cavity connected to the intestine, pancreas and other organs.
Waist circumference: People with more visceral fat has a higher waist circumference.

Absorption: When digestion is completed, the components will absorbed in the cells of the colon and diffused across the body
Chemical breakdown: chemical breakdown is carried out by so-called digestive enzymes produced by various cells and tissues along the alimentary tract.
Cholecystokinin: stimulates the contraction of the gallbladder and distribution of gall.
Colorectal cancer: a common form of cancer that affects the colon or the rectum.
Constipation: describes the condition of having infrequent bowel movements that are hard to pass.
Diarrhea: describes the condition of having loose watery stools that often requires frequent bathroom visits.
Esophagus: a hollow tube that transports the food bolus from the mouth to the stomach.
Hemorrhoids: swollen and inflamed veins around the anus or in the lower rectum.
Hydrochloric acid: Parietal cells in the wall of the stomach produce hydrochloric acid accounting for an unique feature of the interior of the stomach: its high acidity. Goblet cells are spread around the entire intestinal wall and produce mucus. In the stomach they are also referred to as foveolar cells. The mucus covers the interior lining of the stomach and protects it from the acid environment and from degradation by the proteolytic activity of pepsin.
Hydrolyse: the chemical breakdown of a compound due to reaction with water. 
Ileum: is the last portion of the small intestine where most of nutrient absorption takes place. 
Jejunem: is the second and middle section of the small intestine. It is located between the duodenum and ileum. It is the major site of nutrient digestion to generate the basic chemical components that the body can absorb. 
Lower sphincter: prevents reflux of food from the stomach. 
Mechanical breakdown: Breaking down of macronutrients (proteins, fats, and carbohydrates) in their smallest form by the teeth and contraction of muscles in the entire digestive system. 
Pancreas: An approximately 30cm long tube that connects the stomach to the intestines. 
Saliva: 99% water, with the remainder consisting of salts, mucus, enzymes (mainly amylase), and anti-bacterial compounds. Initiates the chemical digestion of food, it has anti-microbial function and is important for tasting. 
Secretin and cholecystokinin: Have a variety of other actions including stimulating the pancreas to release bicarbonate and digestive enzymes. 
Stomach: is a hollow bag with a very muscular wall that is situated between the esophagus and the duodenum. 
Villi: finger-like projections of the intestinal wall. Each villus (singular of villi) has a network of incoming and outgoing blood vessels and a lymphatic vessel called lacteal.