Flow-Mediated Dilation (FMD)
Flow-mediated dilation (FMD) is the widening of an artery in response to increased blood flow. The term also names a noninvasive ultrasound test used to assess this response, usually in the brachial artery of the upper …
Browse the journal
Knowledge
Follow journal articles connected to Alpekin knowledge topics.
536
published entries
Explore articles
Knowledge
Folic acid
Folic acid is the fully oxidized form of folate commonly used in fortified foods and dietary supplements. Folate, also known as vitamin B9, is a water-soluble vitamin that includes folic acid as well as naturally occurring …
Food Allergy
A food allergy is an adverse health effect caused by a specific immune response that occurs reproducibly after exposure to a particular food. The substances that trigger these reactions are called food allergens and are usually …
Food Fortification
Food fortification deliberately adds vitamins or minerals to foods to improve nutrient intake, often targeting deficiencies within a population.
Foodborne Illness
Foodborne illness, also called foodborne disease, is illness caused by consuming food or drink contaminated with a harmful biological or chemical agent. Causes include bacteria, viruses, parasites, toxins, and other chemical substances. Although foodborne illness is …
Foodborne Pathogens
Foodborne pathogens are disease-causing biological agents that can be transmitted to humans through contaminated food or beverages. They include pathogenic bacteria, viruses, and parasites. Examples include Salmonella, Campylobacter, Listeria monocytogenes, norovirus, hepatitis A virus, and foodborne …
Fortified Foods
Fortified foods are foods to which one or more nutrients have been deliberately added to increase their nutrient content. Fortification most commonly involves micronutrients such as vitamins and minerals, including iron, iodine, folic acid, vitamin A, …
Free Radicals
Free radicals are atoms, molecules, or other molecular entities that contain at least one unpaired electron. Electrons commonly occupy orbitals in pairs, so an unpaired electron gives a radical distinctive chemical properties. The term “radical” is …
Free Sugars
Free sugars include added sugars and sugars in juice or honey, while sugars enclosed within intact fruit fall outside the WHO definition.
Frostbite
Frostbite is a localized cold injury in which body tissue freezes. It occurs when tissue temperature falls sufficiently for ice to form within the tissue, most often affecting exposed or poorly insulated areas such as the …
Fructans
Fructans are carbohydrates built mainly from linked fructose units. The name describes a family of molecules rather than a single substance: their chains can differ in length and structure. Inulin and the shorter fructooligosaccharides, often abbreviated …
Fructose
Fructose is a six-carbon monosaccharide, or simple sugar, with the molecular formula C6H12O6. It is a ketohexose, meaning that its open-chain form contains a ketone group. Fructose occurs naturally as a free sugar and is also …
Functional MRI (fMRI)
Functional MRI detects blood-related changes associated with neural activity, providing an indirect signal that also depends on vascular responses.
GLP-1
GLP-1 links nutrients arriving in the gut with glucose regulation, stimulating insulin in a glucose-dependent way while also affecting digestive function.
GLUT4
GLUT4 increases glucose entry when insulin or muscle contraction moves more transporters to the cell surface, where glucose crosses down its gradient.
Gallstones
Gallstones form from bile components and may remain symptom-free, while their location and obstruction of bile flow determine many clinical effects.
Gastric Distension
Gastric distension is the expansion of the stomach as its volume increases, most commonly when food or liquid enters during a meal. As the stomach fills, its wall stretches and wall tension changes. These mechanical changes …
Gastric Emptying
Gastric emptying is the process by which the stomach transfers its contents into the duodenum, the first part of the small intestine. The gastric emptying rate describes how quickly this transfer occurs. The stomach does not …
Gastroesophageal Reflux
Gastroesophageal reflux moves stomach contents into the esophagus, while reflux disease involves troublesome symptoms or complications from that process.
Gastrointestinal Tolerance
Gastrointestinal tolerance refers to how well a person can consume a food, ingredient, or nutrient without experiencing troublesome digestive symptoms. In nutrition research, it is commonly assessed using reported symptoms such as bloating, flatulence, abdominal pain …
Glucagon
Glucagon is a 29-amino-acid peptide hormone produced and secreted mainly by alpha cells in the pancreatic islets. It is an important regulator of blood glucose, particularly when glucose availability is low. Low blood glucose is an …
Gluconeogenesis
Gluconeogenesis is the metabolic pathway that produces glucose from noncarbohydrate precursors. It is particularly important when glucose is not being supplied continuously from food, such as during fasting. In humans, gluconeogenesis occurs mainly in the liver …
Glucose
Glucose is a six-carbon monosaccharide, or simple sugar, with the molecular formula C6H12O6. It is an aldohexose, and the naturally predominant form is D-glucose. Glucose circulates in the bloodstream and can be obtained from the digestion …
Glucose Tolerance Test
A glucose tolerance test measures the response to a defined glucose load, with interpretation tied to the protocol, sampling times and clinical purpose.
Gluteal Muscles
The gluteal muscles commonly refer to three major muscles in the buttock region: the gluteus maximus, gluteus medius, and gluteus minimus. They extend from the pelvis to structures on the femur or the iliotibial tract and …
Gluten
Gluten is a complex mixture of storage proteins found in wheat grain. Its two major protein groups are gliadins and glutenins, each of which contains many related proteins. These proteins are particularly rich in the amino …
Glycemic Index
The glycemic index (GI) is a measure that ranks carbohydrate-containing foods according to the blood glucose response produced by a fixed amount of their available carbohydrate. It is determined by comparing the blood glucose response to …
Glycemic Load
Glycemic load (GL) is a measure that combines the glycemic index of a carbohydrate-containing food with the amount of available carbohydrate in the portion consumed. It is intended to represent the potential glycemic impact of that …
Glycogen
Glycogen is a highly branched polysaccharide composed of glucose and is the principal storage form of glucose in animals. Its glucose units are joined mainly by α(1→4) glycosidic bonds, with α(1→6) bonds creating branch points. This …
Glycogen Resynthesis
Glycogen resynthesis is the rebuilding of glycogen stores after they have been depleted or reduced. Glycogen is a branched polymer of glucose stored mainly in skeletal muscle and the liver. In exercise physiology, glycogen resynthesis usually …
Glycogenolysis
Glycogenolysis is the metabolic process by which glycogen, the stored polymer of glucose, is broken down to make its glucose units available for metabolism. It occurs mainly in the cytosol and is especially important in the …
Glycolysis
Glycolysis is a metabolic pathway that converts glucose, a six-carbon sugar, into two molecules of pyruvate, each containing three carbons. It takes place in the cytosol and consists of ten enzyme-catalyzed reactions. Glycolysis captures some of …
Golgi Tendon Organ
A Golgi tendon organ, or GTO, is a sensory receptor associated with skeletal muscle that detects mechanical force or tension produced through the muscle-tendon system. Golgi tendon organs are located mainly at myotendinous and myoaponeurotic junctions, …
Gut Hormones
Gut hormones are signaling molecules released by specialized endocrine cells in the gastrointestinal tract. Many are produced by enteroendocrine cells scattered throughout the stomach and intestinal epithelium. Examples include gastrin, cholecystokinin, glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1, …
Gut Microbiota
The gut microbiota is the community of microorganisms that inhabits the gastrointestinal tract. It includes bacteria and archaea as well as microbial eukaryotes such as fungi. These organisms are not distributed uniformly along the digestive tract. …
H Zone
The H zone, also called the H band, is the central region of the A band in a sarcomere where thick, myosin-containing filaments are present without overlapping thin, actin-containing filaments. It lies around the center of …
HDL
HDL, or high-density lipoprotein, is a class of lipoprotein particles that transports cholesterol and other lipids through the blood. HDL particles are relatively small and dense compared with triglyceride-rich lipoproteins and contain a mixture of phospholipids, …
HDL-C
HDL-C, or high-density lipoprotein cholesterol, is the concentration of cholesterol carried within high-density lipoprotein particles in the blood. It is typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L) and is one of …
Habit Strength
Habit strength describes how strongly recurring cues prompt a learned response, rather than simply counting how often the behavior occurs.
HbA1c
HbA1c reflects longer-term glucose exposure through glycated hemoglobin, but red-cell lifespan and other factors can alter its relationship to average glucose.
Heat Acclimatization
Heat acclimatization is the set of physiological adaptations that develops after repeated exposure to a hot environment. These adaptations reduce the physiological strain produced by subsequent heat exposure, particularly during physical activity, and improve the body's …
Heme
Heme is an iron-containing porphyrin complex that serves as a tightly bound component, or prosthetic group, of many proteins. Its central iron atom is coordinated within a ring-shaped porphyrin structure. A major form in humans is …
Hepatic Glucose Production
Hepatic glucose production (HGP) is the production and release of glucose by the liver into the bloodstream. It is an important part of glucose homeostasis, particularly when glucose is not being absorbed from a recent meal. …
Hepatic Insulin Sensitivity
Hepatic insulin sensitivity is the degree to which the liver responds to insulin, particularly insulin's ability to suppress hepatic glucose production. In the fasting state, the liver helps maintain blood glucose through glycogen breakdown and gluconeogenesis. …
Hepatic Steatosis
Hepatic steatosis accumulates fat inside liver cells when supply exceeds disposal, describing a tissue finding rather than one disease or liver scarring.
Hesperidin
Hesperidin is a naturally occurring plant compound found in citrus fruits, including their peels. It belongs to the flavanones, a subgroup of flavonoids. More specifically, it is a flavanone glycoside: a molecule in which a flavanone …
High-Fructose Corn Syrup (HFCS)
High-fructose corn syrup (HFCS) is a liquid nutritive sweetener made from corn starch and composed mainly of the simple sugars glucose and fructose. Corn starch is first hydrolyzed to produce a glucose-rich corn syrup. The enzyme …
High-Intensity Sweeteners
High-intensity sweeteners are substances used to produce a sweet taste at much lower amounts than table sugar, or sucrose, because they are many times sweeter. Their high sweetness potency means that only small quantities are needed …