Glossary

Sugars added during processing (such as sucrose or dextrose), sugars packaged as sweeteners, sugars from syrups and honey, and sugars from concentrated fruit or vegetable juices. They do not include sugars naturally present in milk, fruit and vegetables. The Daily Value for added sugars is 50 g a day, based on a 2,000-calorie diet.^[1] See how to read an electrolyte drink label.

A reference intake used instead of an RDA when there is not enough evidence to calculate an Estimated Average Requirement. It is based on observed or experimentally derived intakes of healthy people and is expected to meet or exceed the needs of essentially everyone in the group.^[2] Potassium and total water are examples of nutrients with an AI rather than an RDA.^[3][4]

The desire to eat, as distinct from satiety, the sense of having eaten enough. Appetite is shaped by gut hormones as well as by habit and environment; GLP-1, released from the gut after meals, appears to be a physiological regulator of appetite and food intake.^[5] See what to eat when you're not hungry.

How much of a substance is absorbed and becomes available to the body, and how quickly. US drug regulations define it as the rate and extent to which an active ingredient is absorbed and becomes available at its site of action.^[6] For nutrients, the chemical form matters: the folate reference values, for example, adjust for food folate being less bioavailable than folic acid.^[7] See citrate.

Body weight in kilograms divided by the square of height in meters, reported in kg/m². It is a quick screening number used in research and clinical guidelines, not a direct measure of body fat. A 2025 joint advisory notes that BMI-based measures can both underestimate and overestimate body fat in individuals.^[8] See lean mass.

A seven-point picture scale that grades stool form from pellet-like to liquid; clinicians use it to describe constipation, and research criteria treat types 6 and 7 as loose or watery.^[9] In a study of 66 volunteers, stool form on the scale tracked whole-gut transit time more closely than bowel-movement frequency did.^[10]

The most abundant mineral in the body: over 99 percent of it is in bones and teeth.^[11] The RDA for adults is 1,000 mg a day, rising to 1,200 mg for women over 50 and everyone over 70. The UL is 2,500 mg a day to age 50 and 2,000 mg after.^[12] See the calcium monograph.

A category of Dietary Reference Intake introduced in the 2019 sodium and potassium report, based on evidence about chronic disease rather than deficiency. The sodium CDRR for adults is to reduce intake if it is above 2,300 mg a day. The committee found too little evidence to set a CDRR for potassium.^[3] See sodium.

The salt form of citric acid, used to deliver minerals such as magnesium, zinc, calcium, sodium and potassium. In a 60-day randomized trial in 46 adults, magnesium citrate and an amino-acid chelate were absorbed better than magnesium oxide, and citrate raised blood magnesium the most.^[13] In a crossover study in 15 adults, zinc from zinc citrate was absorbed as well as from zinc gluconate and better than from zinc oxide.^[14] Replenish uses citrate forms of its five minerals. See bioavailability.

Infrequent stools, usually fewer than 3 bowel movements a week, often with straining, a feeling of incomplete emptying, or hard or lumpy stools. The Rome IV research criteria for functional constipation require 2 or more such symptoms in more than a quarter of bowel movements, with symptoms for the past 3 months and onset at least 6 months earlier.^[9] See fiber and staying regular.

A single reference amount the FDA sets for each nutrient on Nutrition Facts and Supplement Facts labels: the amount to consume, or not to exceed, each day. Examples: vitamin C 90 mg, magnesium 420 mg, sodium 2,300 mg, dietary fiber 28 g.^[15] DVs are label tools; they are not the same as the age- and sex-specific DRIs. See %DV.

A loss of body water that outpaces intake. When water losses exceed solute losses, the concentration of the blood, its osmolality, rises, and plasma osmolality is the main indicator of hydration status.^[4] Older adults show a reduced thirst response when dehydrated.^[16] See GLP-1s, thirst and dehydration.

Carbohydrate that resists digestion in the small intestine. Fibers differ in four properties that drive their effects: whether they dissolve, how far and how fast gut bacteria ferment them, whether they thicken, and whether they gel.^[17] The Daily Value is 28 g.^[15] See soluble fiber, fermentable fiber and how much fiber a day.

The unit used for folate reference values. It adjusts for the lower bioavailability of food folate: 1 µg DFE equals 1 µg of food folate, 0.6 µg of folic acid from fortified food or a supplement taken with meals, or 0.5 µg of a supplement taken on an empty stomach.^[7] Labels list folate in mcg DFE.^[15] See folate.

The umbrella term for the nutrient reference values set by the National Academies for the US and Canada. They include the RDA, AI, UL and EAR, each set for life-stage and sex groups.^[2] The 2019 sodium and potassium report added a further category, the CDRR.^[3]

A product taken by mouth that contains a "dietary ingredient," such as a vitamin, mineral, herb, amino acid or similar substance, intended to supplement the diet. Congress defined the term in the Dietary Supplement Health and Education Act (DSHEA) of 1994. Under DSHEA, the FDA does not approve dietary supplements before they are sold.^[18] See what supplements to take.

A mineral that carries an electric charge when dissolved in body fluids. Sodium, about 95 percent of it outside cells, and potassium, about 98 percent inside cells, are the main examples; together they maintain fluid volume and the charge across cell membranes that nerves and muscles depend on.^[19] Magnesium, calcium and chloride are also electrolytes. See do you need electrolytes.

A sugar alcohol used as a sugar substitute. In 2023 the FDA reviewed a paper on possible cardiovascular effects of erythritol and concluded that the observational studies it cited did not establish a causal link; the agency says it will keep monitoring new information.^[20] Replenish lists erythritol under Other Ingredients. See the erythritol monograph.

The daily intake estimated to meet the needs of half the healthy people in a life-stage and sex group; the other half would not have their needs met at that level. The EAR is the basis for the RDA and is used mainly to assess the intakes of groups, such as in national surveys.^[2]

The statement required beside a structure/function claim on a supplement label: "This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease." It must be in bold type no smaller than one-sixteenth of an inch.^[21] On zornava.com the dagger (†) after a claim links to it.

Fiber that gut bacteria break down after it passes undigested through the small intestine, producing short-chain fatty acids and gas.^[17] Rapidly fermented fibers such as inulin are largely gone before they reach the stool, and they are the type most linked to extra gas.^[17][22] See fiber supplements compared.

A water-soluble B vitamin that works in single-carbon transfer reactions, including DNA synthesis. The adult RDA is 400 µg DFE a day. The UL, 1,000 µg a day, applies only to folate from fortified food or supplements, not to food folate.^[7] Replenish uses L-5-methyltetrahydrofolate. See the folate monograph.

The US Department of Agriculture's food composition database, with several data types: analytical data on minimally processed foods, historical legacy data, the foods reported in national dietary surveys, and branded products.^[23] Our articles use it for the nutrient content of foods. See what to eat when you're eating less.

The rate at which food leaves the stomach for the small intestine. The gut hormone GLP-1 slows gastrointestinal motility as part of the ileal brake,^[5] and GLP-1 medications delay gastric emptying, which can cause bloating and fullness. Foods that are lower in fat and protein, thinner and more watery tend to leave the stomach faster.^[8] See eating on queasy days.

An incretin hormone made by K cells in the upper small intestine and released after eating. Like GLP-1, it amplifies insulin release when blood glucose is high. Its effect on the pancreas is substantially reduced in type 2 diabetes.^[24] See GLP-1.

A 30-amino-acid hormone made by L cells in the gut lining and released after meals. It stimulates insulin release, suppresses glucagon, slows gastrointestinal motility and appears to regulate appetite. The natural hormone is broken down very rapidly by the enzyme dipeptidyl peptidase-4, much of it before it leaves the gut.^[5] See GLP-1 receptor agonist and what is the GLP-1 diet.

A class of prescription medicines that activate the same receptor as the hormone GLP-1 but act far longer than the natural hormone.^[25] They lower blood glucose and reduce appetite and food intake.^[24] They are prescribed for type 2 diabetes and for obesity. Nutrition priorities during treatment include protein, fluids, fiber and micronutrients.^[8] See the GLP-1 nutrition guide.

A ranking of carbohydrate foods by how much they raise blood glucose. In the original 1981 method, the area under the 2-hour blood glucose curve after a food is expressed as a percentage of the response to the same amount of carbohydrate taken as glucose.^[26] Fat and protein in a food were linked to a smaller glucose rise in that study.^[26]

The community of bacteria and other microbes living in the intestine, mostly the colon. They ferment fibers the body cannot digest and produce metabolites such as short-chain fatty acids, which act on the host's cells.^[27] Whether a change in these microbes improves health has to be shown for each substance; that requirement is part of the definition of a prebiotic.^[28]

A low blood potassium level, below the normal range of 3.5 to 5.0 mEq/L; levels below 2.5 mEq/L are severe. Symptoms usually appear only below 3.0 mEq/L. Common causes include diuretic medicines and potassium lost through prolonged vomiting or diarrhea.^[29] It is diagnosed with a blood test, not by symptoms. See potassium.

A low blood magnesium level. One 2026 clinical update defines it as serum magnesium below 0.6 mmol/L, with symptoms usually appearing below 0.5 mmol/L; reference ranges vary between laboratories.^[30] Long-term use of proton pump inhibitors is associated with it in observational studies.^[31] Ask your prescriber or pharmacist if you take acid reducers or diuretics. See magnesium.

A low blood sodium concentration, usually defined as below 135 mmol/L. It becomes more common with age.^[32] Drinking large volumes of plain water can cause it: in the 2002 Boston Marathon, 13 percent of 488 runners tested had hyponatremia, linked mainly to weight gain during the race, a sign of drinking more than was lost, and to long race times.^[33] See sodium and how much water to drink.

A feedback loop in which nutrients reaching the lower small intestine slow the movement and secretions of the upper gut, so that food is processed more slowly. GLP-1, released from cells in the intestinal lining, is part of this mechanism.^[5] See gastric emptying.

A gut hormone released after eating that boosts insulin secretion. GIP and GLP-1 are the two known incretins. Together they explain the incretin effect: insulin release is two to three times higher after glucose taken by mouth than after the same glucose given into a vein.^[24] See GIP and GLP-1.

Fiber that does not dissolve in water, such as wheat bran. It does not thicken or gel and is poorly fermented. Coarse particles can have a laxative effect by stimulating the bowel lining; finely ground bran has little such effect.^[17] Most foods contain a mix of soluble and insoluble fiber. See soluble fiber.

A soluble, non-viscous fiber that gut bacteria ferment rapidly and completely.^[17] Constipation trials have used 12 to 15 g a day, and it is the fiber type most linked to extra gas in trials.^[22] See fermentable fiber and fiber supplements compared.

Everything in the body that is not fat: muscle, bone, organs and water. Muscle is about half of it. When body weight falls, part of the reduction comes from lean mass, and how much depends on the degree of calorie restriction, the speed of the change and whether a person does strength training.^[8] Whether lean mass changes during GLP-1 treatment affect function is still unresolved.^[34] See keeping muscle.

A mineral that is a required cofactor for over 300 enzyme systems, including energy production. The adult RDA is 400 to 420 mg a day for men and 310 to 320 mg for women. The UL, 350 mg a day, applies only to magnesium from supplements and medicines, because diarrhea is the first sign of excess from those sources.^[35] See the magnesium monograph.

A statistical method that pools the results of several studies of the same question into one combined estimate, usually as part of a systematic review. A meta-analysis is only as good as the studies it combines. Example: a 2022 meta-analysis of fiber supplement trials in adults with chronic constipation.^[22] See randomized controlled trial.

A naturally occurring form of vitamin B12 used in supplements, alongside synthetic cyanocobalamin. A 2017 literature analysis reports that every supplemental or food form of B12 is reduced to the same core cobalamin inside cells, which are then converted to the active forms in a ratio not influenced by the form taken.^[36] Replenish uses methylcobalamin. See the vitamin B12 monograph.

L-5-methyltetrahydrofolate, the main form of folate in food and the form that normally circulates in the blood. Folic acid, the synthetic form, must be converted before the body can use it. Studies comparing the two found comparable bioavailability at equal molar doses; methylfolate is sold as a stable calcium salt.^[37] Replenish uses L-5-methyltetrahydrofolate calcium. See folate.

A vitamin or mineral: a nutrient needed in milligram or microgram amounts, as opposed to the macronutrients (protein, carbohydrate and fat) needed in grams. When food intake falls, micronutrient intake usually falls with it, which is why a 2025 joint advisory lists micronutrients among the nutrition priorities during GLP-1 treatment.^[8] See which vitamins matter.

Extract of the fruit of Siraitia grosvenorii, also called luo han guo, a plant native to southern China. Its sweetness comes from compounds called mogrosides, and depending on mogroside content the extract is reported to be 100 to 250 times sweeter than sugar. The FDA has not questioned GRAS notices for its use as a sweetener.^[20] See the monk fruit monograph.

The national health and nutrition survey run by the CDC's National Center for Health Statistics, with its own sample design and survey weights for analysis. It has run continuously since 1999, with data released in two-year cycles.^[38] Many published estimates of how many Americans fall short of a nutrient use NHANES data.^[39] See the Nutrition Gap Report.

A study that measures what people already do, such as their diet or medicines, and compares outcomes, without assigning anyone to a treatment. It can show an association but not, on its own, cause and effect. For example, the FDA concluded in 2023 that observational studies linking erythritol to cardiovascular events did not establish a causal link.^[20] Compare randomized controlled trial.

A drink of water, glucose and salts designed to replace fluid lost in diarrhea. It works because glucose and sodium are absorbed together by a transporter in the small intestine, pulling water with them. The current WHO-UNICEF formula contains 75 mM glucose, 75 mM sodium, 65 mM chloride, 20 mM potassium and 10 mM citrate, for a total of 245 mOsm/kg.^[40] See osmolality.

The concentration of dissolved particles in a fluid, per kilogram of water. In the blood it is held tightly around 280 to 290 mOsm/kg and rarely varies by more than 2 percent; when it rises, the body releases vasopressin, which reduces urine output, and thirst increases. The set point rises with age.^[4] See dehydration and thirst.

A water-soluble fiber made by partly breaking down guar gum, which removes its gel-forming thickness so it dissolves clear in drinks.^[41][17] Gut bacteria ferment it readily.^[42] In a 3-month placebo-controlled trial in 44 adults with a tendency to loose stools, 5 g a day normalized stool form compared with placebo; stool frequency did not change.^[43] Replenish is formulated with 3.5 g of PHGG. See the PHGG monograph.

How much one serving contributes toward the Daily Value of a nutrient. If the DV is 300 mcg and a serving has 30 mcg, the %DV is 10 percent. As a general guide, the FDA treats 5 percent DV or less per serving as low and 20 percent or more as high.^[15] See Supplement Facts panel.

An inactive look-alike given to a comparison group in a trial so that participants, and ideally researchers, cannot tell who is receiving the real treatment. Any difference between groups can then be attributed to the treatment rather than to expectation. The PHGG trial cited on this page, for example, was double-blind and placebo-controlled.^[43] See randomized controlled trial.

Two identifiers that let you find a cited paper. A PMID is the number PubMed, the US National Library of Medicine's index of biomedical literature, assigns to each record. A DOI (Digital Object Identifier) is a permanent link to the published article itself. Our reference lists give both where they exist; see the references at the end of this page.

The main electrolyte inside cells, where about 98 percent of the body's potassium is held.^[19] The adult Adequate Intake is 3,400 mg a day for men and 2,600 mg for women. No UL was set, because evidence of toxicity risk in healthy people was insufficient.^[3] See the potassium monograph.

"A substrate that is selectively utilized by host microorganisms conferring a health benefit," in the 2017 consensus definition from the International Scientific Association for Probiotics and Prebiotics. A health benefit must be documented for a substance to qualify; feeding gut bacteria is not enough on its own.^[28] See gut microbiota.

Protein needs are usually expressed per kilogram of body weight. The adult RDA is 0.8 g/kg a day; higher targets of 1.2 to 1.6 g/kg have been proposed while body weight is falling. For people with obesity it is unclear which body weight to use, and actual weight can overestimate needs.^[8] See how much protein.

A soluble fiber that forms a gel and is not fermented, so it holds water all the way through the bowel.^[17][42] It has the strongest trial evidence among fiber supplements for chronic constipation, at more than 10 g a day.^[22] Gel-forming fibers carry an FDA warning to take them with a full glass of liquid.^[44] See viscous fiber.

A study that assigns participants by chance to a treatment or a comparison, often a placebo, and compares outcomes. Randomization balances the groups, so differences can be attributed to the treatment. It is the strongest single-study design for cause and effect. Example: a 60-day double-blind trial comparing three forms of magnesium with placebo in 46 adults.^[13] Compare observational study.

One of the sweet steviol glycosides of the stevia plant. Commercial Reb M can be made by fermentation or by enzymatic conversion of other steviol glycosides purified from stevia leaves.^[45][46] Because all steviol glycosides follow the same metabolic pathways, the European Food Safety Authority applies the group acceptable daily intake of 4 mg per kg of body weight, as steviol equivalents, to Reb M.^[45] See the Reb M monograph.

The average daily intake that meets the needs of nearly all (97 to 98 percent) healthy people in a life-stage and sex group. It is set above the EAR and is meant as a daily goal for individuals.^[2] Where no RDA can be set, an AI is used.

Exercise in which muscles work against a load, such as weights, bands or body weight. US guidelines recommend muscle-strengthening activity for all major muscle groups on two or more days a week.^[47] Structured resistance or mixed training is well established to help preserve lean mass while body weight falls; aerobic activity alone has a smaller effect.^[8] See keeping muscle.

A muscle disease defined chiefly by low muscle strength, confirmed by low muscle quantity or quality; poor physical performance marks severe sarcopenia. It is common in older adults but can occur earlier in life. That is the 2019 definition of the European Working Group on Sarcopenia in Older People.^[48] See lean mass and resistance training.

The feeling of fullness that follows a meal and delays the next one, as distinct from appetite. Signals from the stomach and gut hormones contribute; GLP-1 slows gut motility and appears to regulate food intake.^[5] Protein-induced GLP-1 release appears to play a part in satiety, though the mechanism is poorly understood.^[8] See gastric emptying.

Small fatty acids produced when gut bacteria ferment fiber.^[17] They serve as an energy source for cells and act as signaling molecules, including by activating receptors on the cells they reach.^[27] See fermentable fiber and gut microbiota.

The main electrolyte outside cells: about 95 percent of the body's sodium is extracellular, where, with chloride, it maintains fluid volume and plasma osmolality.^[19] The adult Adequate Intake is 1,500 mg a day, and the CDRR advises reducing intake above 2,300 mg.^[3] See the sodium monograph.

Fiber that dissolves in water. Within this group, some fibers thicken (viscous), some form a gel, and some do neither; some are rapidly fermented and some are not. Those differences, more than solubility itself, determine what a fiber does.^[17] Psyllium, inulin and PHGG are all soluble but behave differently. See fiber supplements compared.

The sweet compounds in the leaves of Stevia rebaudiana, a plant native to parts of South America, reported to be 200 to 400 times sweeter than table sugar. The FDA has not questioned GRAS conclusions for high-purity (at least 95 percent) steviol glycosides used as general-purpose sweeteners.^[20] In 2024 the European Food Safety Authority kept its acceptable daily intake at 4 mg per kg of body weight a day, as steviol equivalents.^[49] See Reb M and the Reb M monograph.

A statement on a supplement label describing the role of a nutrient or ingredient in the normal structure or function of the body, such as "supports hydration." It may not be a disease claim; a product claiming to treat or prevent a disease is regulated as a drug. Each such claim must carry the FDA disclaimer, and the FDA must be notified within 30 days of marketing.^[21]

A class of sweeteners, including sorbitol, xylitol, mannitol, maltitol and erythritol, that the FDA permits as sugar substitutes. They range from 25 to 100 percent as sweet as sugar, are slightly lower in calories, do not promote tooth decay and do not cause a sudden rise in blood glucose.^[20] See reading an electrolyte drink label.

The nutrition label required on dietary supplements, titled "Supplement Facts" in type larger than anything else on the label. It lists the serving size and the amount and %DV of each dietary ingredient; ingredients with no Daily Value are marked "Daily Value not established."^[50] Other ingredients, such as sweeteners and flavors, are listed below the panel.

A study of studies that answers a defined question by searching the literature with a stated method, applying set inclusion criteria and appraising every eligible study, so that the answer does not depend on which papers an author happened to pick. It often includes a meta-analysis. Example: the 2022 systematic review of fiber supplements for chronic constipation.^[22]

Temporary, diffuse hair shedding that happens when more hair follicles than usual enter the resting (telogen) phase. Shedding typically starts two to three months after a trigger such as surgery, high fever, chronic illness or childbirth. The acute form lasts less than six months, and most cases resolve.^[51] See which vitamins matter and zinc.

A water-soluble B vitamin that works as a coenzyme in the metabolism of carbohydrates and branched-chain amino acids. The adult RDA is 1.2 mg a day for men and 1.1 mg for women.^[52] Replenish uses thiamine mononitrate. See the thiamin monograph and why GLP-1s can leave you tired.

The urge to drink, triggered mainly by a rise in blood osmolality or a fall in blood volume. Older adults have a blunted thirst response to these signals.^[16] GLP-1 receptor activation reduced water intake in rats, independent of food intake,^[25] and in people, longer-term treatment has been reported to reduce fluid intake.^[53] See GLP-1s, thirst and dehydration.

The highest daily intake likely to pose no risk of adverse health effects for almost everyone in a group. Above it, risk rises. The UL is a ceiling, not a target.^[2] Some ULs cover only supplements and fortified foods, such as those for magnesium and folate.^[35][7] "ND" means not determined.

All the water you take in from drinking water, other beverages and food. The Adequate Intake for adults aged 19 to 30 is 3.7 L a day for men and 2.7 L for women, of which drinks supplied about 3.0 L and 2.2 L in US survey data, roughly 81 percent.^[4] See how much water to drink.

Soluble fiber that thickens when mixed with water, in proportion to how much is present; some viscous fibers go further and form a gel. In the small intestine, viscous gel-forming fibers such as psyllium and raw guar gum thicken the contents and slow the mixing of food with digestive enzymes.^[17] PHGG is guar gum with that thickness removed. See soluble fiber.

A group of six related compounds, including pyridoxine, pyridoxal and pyridoxamine. The RDA for young adults is 1.3 mg a day, and the adult UL is 100 mg a day.^[54] Replenish uses pyridoxine hydrochloride. See the vitamin B6 monograph.

A vitamin found naturally in animal foods. The adult RDA is 2.4 µg a day, and no UL has been set. Because 10 to 30 percent of older people may not absorb the B12 bound in food, the National Academies advise people over 50 to get most of it from fortified foods or a supplement.^[55] See methylcobalamin and the vitamin B12 monograph.

A water-soluble vitamin, also called ascorbic acid, that humans cannot make. The adult RDA is 90 mg a day for men and 75 mg for women, with 35 mg more for people who smoke. The UL is 2 g a day, based on diarrhea and stomach upset at higher intakes.^[56] See the vitamin C monograph.

A fat-soluble vitamin; its active form stimulates calcium absorption in the intestine.^[57] The adult RDA is 600 IU (15 µg) a day to age 70 and 800 IU (20 µg) after; the UL is 4,000 IU (100 µg).^[12] Replenish uses vitamin D3 (cholecalciferol). See the vitamin D monograph.

A trace mineral needed for growth and for many enzymes. The adult RDA is 11 mg a day for men and 8 mg for women, and the UL is 40 mg a day, set on the basis of reduced copper status at higher intakes.^[58] Replenish uses zinc citrate. See the zinc monograph.