Supplement Glossary
61 key terms and concepts you will encounter when researching supplements. Understanding these will help you read labels, evaluate research, and make more informed purchasing decisions.
A
Active Ingredient
The specific compound in a supplement responsible for its biological effects. For example, the active ingredient in turmeric supplements is curcumin, which makes up only about 3% of raw turmeric. The form, dose, and bioavailability of the active ingredient are what determine whether a supplement actually works.
Adaptogen
A class of herbs and mushrooms claimed to help the body resist physical, chemical, and biological stressors. Ashwagandha, rhodiola, and ginseng are the most well-studied adaptogens. Evidence quality varies significantly by ingredient - ashwagandha has reasonably strong RCT support for stress reduction, while many others have limited human data.
Amino Spiking
A deceptive practice where cheap amino acids (like glycine or taurine) are added to a protein powder to inflate the total protein number on the label. The nitrogen test used to measure protein cannot distinguish between complete protein and free amino acids. This means you may be getting less functional protein than the label claims. We consider this a serious quality issue.
B
Beta-Glucan
A type of soluble fiber found in the cell walls of certain mushrooms, yeast, oats, and barley. Mushroom-derived beta-glucans (1,3/1,6) are studied for immune modulation, while oat-derived beta-glucans (1,3/1,4) are studied for cholesterol reduction. The source and structure of beta-glucan matter - they are not interchangeable between applications.
Bioavailability
The proportion of a supplement that enters your bloodstream and is available for use by the body. Higher bioavailability means more of what you swallow actually gets absorbed. This is why the form of an ingredient matters - magnesium glycinate has far higher bioavailability than magnesium oxide, for example.
BSCG Certified
Banned Substances Control Group certification means the product has been tested for more than 500 drugs and substances banned in sport, as well as contaminants. BSCG is particularly respected in professional and Olympic athletics. Certification involves both finished product testing and manufacturing facility audits.
C
Certificate of Analysis (COA)
A document from a testing laboratory that reports the results of analyses performed on a specific batch of a supplement. COAs typically cover identity, potency, and contaminant testing. Some brands make COAs publicly available on their websites or by request. Availability of COAs is a positive transparency signal.
CFU (Colony-Forming Units)
The standard unit for measuring the number of viable (live) bacteria in a probiotic supplement. Higher CFU count does not necessarily mean a better product - what matters is whether the specific strains are present at the doses shown to be effective in clinical trials. A 10 billion CFU product with well-studied strains can outperform a 100 billion CFU product with unstudied ones.
Chelated Mineral
A mineral bonded to an amino acid or organic compound to improve absorption. Magnesium glycinate (bonded to glycine) and zinc picolinate (bonded to picolinic acid) are common examples. Chelated forms generally have better bioavailability than inorganic forms like oxides or carbonates, though they cost more.
Clinically Effective Dose
The dose shown to produce measurable benefits in randomized controlled trials. This is the foundation of our value scoring. We calculate cost per clinically effective dose, not cost per pill. A cheap product that requires four pills to reach an effective dose is not actually cheaper than a premium product that delivers the effective dose in one pill.
ConsumerLab Approved
ConsumerLab.com has independently purchased and tested the product, verifying that it contains what the label claims and is free from concerning contamination levels. ConsumerLab publishes pass/fail results. A ConsumerLab approval is a solid third-party quality signal, though it is less rigorous than USP or NSF certification.
Cost per Effective Dose
Our key value metric. Calculated by determining the clinically effective daily dose from research, then computing what it costs per day to achieve that dose with a given product. This is far more meaningful than cost per pill or cost per serving - a cheap product that requires three servings to reach an effective dose is often more expensive per effective dose than a premium product that delivers it in one serving.
Curcuminoids
The active compounds in turmeric responsible for its anti-inflammatory properties. Curcumin is the most abundant and well-studied curcuminoid. Raw turmeric contains only about 3% curcuminoids, so supplements use concentrated extracts, typically standardized to 95% curcuminoids. Curcuminoids have very poor absorption on their own - pairing with piperine or using phytosome formulations dramatically improves bioavailability.
D
Daily Value (DV)
The recommended daily intake of a nutrient set by the FDA for general nutrition labeling. Shown as a percentage on Supplement Facts panels. Important caveat: the DV is a general recommendation to prevent deficiency - it is not the same as a clinically effective dose for a specific health benefit, which is often higher.
Double-Blind
A study design where neither the participants nor the researchers know who is receiving the supplement and who is receiving the placebo until the study is completed. This prevents both placebo effects and researcher bias from skewing results. Double-blind RCTs produce the most reliable evidence.
DSHEA
The Dietary Supplement Health and Education Act of 1994. This U.S. law defines dietary supplements as a category of food (not drugs) and established the regulatory framework still in use today. Under DSHEA, supplements do not require FDA approval before being sold, and manufacturers are responsible for ensuring safety and label accuracy. This is why third-party testing is so important - there is no mandatory pre-market verification.
E
Effect Size
A measure of how large or meaningful a treatment effect is, beyond just whether it is statistically significant. A supplement could show a statistically significant benefit that is too small to matter in practice. We consider effect size when evaluating evidence - a large, clinically meaningful effect is worth more than a tiny but statistically significant one.
Elemental Amount
The actual amount of a mineral present in a compound, as opposed to the total weight of the compound. For example, 2,000 mg of magnesium glycinate contains only about 280 mg of elemental magnesium. When evaluating mineral supplements, always check whether the label lists elemental or compound weight. Our scoring is based on elemental amounts.
Enteric-Coated
A coating on a capsule or tablet designed to resist stomach acid and dissolve in the small intestine instead. Used for ingredients that are destroyed by stomach acid (like certain probiotics) or that cause stomach upset (like high-dose fish oil). Can improve efficacy but may also reduce absorption of some nutrients.
EPA / DHA
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the two most important omega-3 fatty acids in fish oil. EPA is primarily associated with anti-inflammatory and cardiovascular benefits. DHA is critical for brain health and is the predominant omega-3 in brain tissue. When scoring fish oil, we evaluate the combined EPA+DHA per serving, not just total fish oil weight.
Ethyl Ester Form (Fish Oil)
A synthetic molecular form of omega-3 created during the concentration process. Cheaper to produce than triglyceride form but has lower bioavailability - roughly 27% less absorption according to some studies. Most budget fish oil uses ethyl esters. Check labels for 'EE' or 'ethyl ester' designations.
F
FDA Disclaimer
The legally required statement on supplement labels: 'These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.' This disclaimer is required whenever a supplement makes a structure/function claim. It exists because supplements, unlike drugs, are not reviewed by the FDA for efficacy before being sold.
Filler
A bulking agent added to a supplement to fill out a capsule or tablet. Some fillers (like rice flour or maltodextrin) add no nutritional value. While fillers are not inherently harmful, excessive filler relative to active ingredient can be a sign of a low-quality product trying to appear more substantial than it is.
G
GMP Certified
Good Manufacturing Practice certification means a facility follows standardized quality procedures for supplement production. The FDA requires supplement manufacturers to follow GMP, but compliance is self-reported unless independently audited by organizations like NSF or NPA. GMP certification alone does not verify that the product label is accurate.
GRAS (Generally Recognized as Safe)
A designation from the FDA indicating that a substance is generally recognized as safe for its intended use based on a long history of common use in food or on published scientific evidence. Many supplement ingredients have GRAS status for specific uses and doses. GRAS status does not mean unlimited safety at any dose - it applies to specific conditions of use.
H
Health Claim
A claim approved by the FDA that describes a relationship between a substance and a disease or health condition. Health claims require significant scientific agreement and FDA authorization. Very few supplement ingredients have approved health claims. Example: 'Calcium and vitamin D may reduce the risk of osteoporosis.' These are far more regulated than structure/function claims.
Heavy Metal Testing
Laboratory analysis checking for lead, mercury, cadmium, and arsenic in a supplement. Heavy metals can accumulate in the body over time and cause serious health problems. Products sourced from contaminated soil or water (some herbs, rice-based proteins) are at higher risk. Third-party certifications like USP and NSF include heavy metal screening.
Hydrolyzed
Broken down into smaller peptides using water and enzymes for easier absorption. Most commonly seen with collagen (hydrolyzed collagen peptides) and whey protein (hydrolyzed whey). Hydrolyzed forms dissolve better and are absorbed faster, though they may not always be more effective than non-hydrolyzed versions.
I
IFOS (International Fish Oil Standards)
A third-party testing and certification program specifically for fish oil and omega-3 products. IFOS tests for potency (EPA/DHA content), purity (heavy metals, PCBs, dioxins), and freshness (oxidation levels). A 5-star IFOS rating is the highest quality mark a fish oil can receive.
In Vitro vs In Vivo
In vitro means tested in a lab setting (literally 'in glass' - test tubes, cell cultures). In vivo means tested in a living organism (animals or humans). Many supplements show promising in vitro results that do not translate to real-world benefits because the body processes compounds differently than isolated cells do. We do not give high evidence scores based on in vitro studies alone.
Inactive Ingredients / Excipients
Non-active components added to a supplement for manufacturing purposes - including capsule materials, flow agents, binders, coatings, and preservatives. Common examples include magnesium stearate, silicon dioxide, and cellulose. Most are harmless, though some people prefer to avoid certain excipients like titanium dioxide or artificial colors.
Informed Choice / Informed Sport
A global quality assurance program for sports nutrition products. Informed Sport tests every batch before release, while Informed Choice tests products on a monthly basis. Both screen for substances prohibited by the World Anti-Doping Agency (WADA). Widely recognized in international athletics.
L
Liposomal
A delivery method that encases a supplement in tiny fat-based spheres (liposomes) to improve absorption. Used commonly with vitamin C, glutathione, and curcumin. Evidence for improved bioavailability is promising but still limited for many ingredients. Liposomal products are typically more expensive.
M
MCT Oil
Medium-chain triglyceride oil, typically derived from coconut or palm kernel oil. MCTs are absorbed and metabolized faster than long-chain fats, providing quick energy. Often used as a carrier oil in supplements and popular in ketogenic diets. The most studied MCTs are C8 (caprylic acid) and C10 (capric acid). C12 (lauric acid) behaves more like a long-chain fat despite being marketed as an MCT.
Meta-Analysis
A statistical method that combines results from multiple studies to produce a more reliable overall estimate of an effect. Generally provides the strongest level of evidence for supplement efficacy. When a meta-analysis of several RCTs confirms a benefit, we consider that strong evidence.
Methylated
Refers to supplement forms that include a methyl group, making them biologically active without requiring conversion by the body. Methylfolate (5-MTHF) and methylcobalamin (B12) are common examples. Roughly 30-40% of the population has MTHFR gene variants that impair conversion of non-methylated forms, making methylated versions important for those individuals.
Microbial Testing
Laboratory analysis checking a supplement for harmful bacteria, yeast, and mold contamination. Particularly important for products like probiotics, protein powders, and herbal extracts. Reputable third-party certification programs include microbial testing in their protocols.
N
Nitrogen Spiking
Another term for amino spiking. The standard test for protein content (Kjeldahl method) measures total nitrogen, which is then converted to an estimated protein amount. Adding cheap nitrogen-containing compounds like free glycine, creatine, or even melamine artificially inflates the protein reading. Third-party tested protein powders are less likely to be nitrogen spiked.
Nootropic
A substance claimed to improve cognitive function, including memory, focus, creativity, or motivation. Ranges from well-studied compounds (caffeine, creatine, citicoline) to poorly-researched proprietary blends. Be skeptical of 'nootropic stack' products using proprietary blends - the evidence for most individual nootropic ingredients is moderate at best.
NSF Certified for Sport
NSF International has tested the product for label accuracy and screened it for 270+ substances banned by major athletic organizations. Required or recommended by the NFL, MLB, NHL, and many college athletics programs. Along with USP, this is the gold standard for supplement quality verification.
P
Phospholipid
A type of fat molecule with a water-attracting head and fat-attracting tails, forming the basis of cell membranes. In supplements, phospholipids are used to improve absorption (as in krill oil, where omega-3s are bound to phospholipids) and as the carrier in phytosome and liposomal delivery systems. Phosphatidylserine and phosphatidylcholine are supplement phospholipids studied for cognitive benefits.
Phytosome
A plant extract bound to phospholipids (usually sunflower lecithin) to dramatically improve absorption. Meriva curcumin is one of the best-known phytosome formulations, with studies showing 29x higher absorption than standard curcumin. Phytosome technology is patented and typically increases product cost.
Piperine / BioPerine
Piperine is the active compound in black pepper. BioPerine is a patented piperine extract standardized to 95% piperine. When taken with curcumin, piperine increases absorption by up to 2,000% by inhibiting the liver enzymes that normally break down curcumin rapidly. Also enhances absorption of some other nutrients. Note: this same enzyme-inhibiting property can interact with certain medications.
Placebo-Controlled
A study that includes a control group receiving an inactive substance (placebo) that looks identical to the supplement being tested. This is essential because people often feel better simply from believing they are taking something (the placebo effect). Without a placebo control, it is impossible to know if a supplement actually works.
Postbiotic
Bioactive compounds produced by probiotic bacteria during fermentation, including short-chain fatty acids, enzymes, and cell wall fragments. Postbiotics are a newer category with growing but still limited research. They have the advantage of being shelf-stable (no live organisms to keep alive).
Prebiotic
A type of fiber or compound that feeds beneficial gut bacteria. Common prebiotics include inulin, fructooligosaccharides (FOS), and galactooligosaccharides (GOS). Unlike probiotics, prebiotics are not live organisms. They work by selectively promoting the growth of beneficial bacteria already in your gut.
Probiotic
Live microorganisms that, when consumed in adequate amounts, provide a health benefit to the host. Strain specificity matters enormously - Lactobacillus rhamnosus GG is well-studied for certain conditions, but that evidence does not extend to other Lactobacillus strains. When evaluating probiotics, look for specific strain designations (not just genus and species) and CFU count.
Proprietary Blend
A combination of ingredients listed on a label without individual amounts. The total blend weight is disclosed, but you cannot determine how much of each ingredient you are getting. Companies claim this protects trade secrets. We consider proprietary blends a transparency red flag because they make it impossible to verify whether key ingredients are present at effective doses.
R
RCT (Randomized Controlled Trial)
The gold standard of clinical research. Participants are randomly assigned to receive either the supplement or a placebo, and ideally neither participants nor researchers know who got what (double-blind). RCTs are the primary evidence we use for our evidence scoring. A supplement backed by multiple large RCTs earns a high evidence grade.
S
Serving Size
The manufacturer's recommended number of pills, capsules, scoops, or milliliters per dose. This is often NOT the clinically effective dose. Some products list a small serving size on the front label but require 2-3 servings to reach the dose used in studies. Always check the Supplement Facts panel and compare to the clinically studied dose.
Standardized Extract
An herbal extract processed to contain a guaranteed minimum percentage of the active compound. For example, KSM-66 ashwagandha is standardized to 5% withanolides, and turmeric extracts are often standardized to 95% curcuminoids. Standardization ensures consistent potency between batches and makes dosing more reliable.
Statistical Significance
A result is statistically significant when it is unlikely to have occurred by chance alone (typically p < 0.05). However, statistical significance does not mean a result is large or practically important. A supplement could produce a statistically significant but clinically meaningless 0.5% improvement. Always look at effect size alongside significance.
Structure/Function Claim
A type of claim supplements are allowed to make under DSHEA, describing how an ingredient affects the normal structure or function of the body. Example: 'supports bone health' or 'promotes healthy immune function.' These claims do not require FDA approval but cannot claim to treat, cure, or prevent a disease. The line between a structure/function claim and a disease claim is legally important but often blurry.
Systematic Review
A comprehensive, methodical search and analysis of all available research on a specific question. Unlike a narrative review (which can cherry-pick studies), a systematic review follows a predefined protocol to minimize bias. Often includes a meta-analysis but not always. We prioritize systematic reviews when evaluating evidence.
T
Third-Party Tested
An independent laboratory (not the manufacturer) has verified the product's contents and purity. The strength of this claim varies widely - USP and NSF certifications are rigorous, while some brands use less-recognized labs. When a product says 'third-party tested,' check which lab and what was tested. We factor the specific certification into our quality score.
Transparency Score
One of our four equally-weighted scoring pillars. Evaluates whether a supplement label clearly discloses all ingredients, their forms, their amounts, and their sources. Products using proprietary blends, vague ingredient descriptions, or missing form information score lower. Full disclosure with no proprietary blends earns the highest transparency grades.
Triglyceride Form (Fish Oil)
The natural molecular form of omega-3 fatty acids as they occur in fish. Fish oil in triglyceride (TG) form is better absorbed than the cheaper ethyl ester form. Most high-quality fish oil supplements use re-esterified triglyceride (rTG) form. This is one of the key quality markers we evaluate when scoring fish oil products.
U
Ubiquinol vs Ubiquinone
Two forms of CoQ10. Ubiquinone is the oxidized form that your body must convert to ubiquinol (the active, reduced form) before use. Ubiquinol supplements skip this conversion step and may be better absorbed, especially for adults over 40 whose conversion ability declines. Ubiquinol is more expensive but typically requires a lower dose.
Upper Tolerable Intake Level (UL)
The maximum daily dose of a nutrient that is unlikely to cause harm in most healthy adults, as set by the National Academies of Sciences. Exceeding the UL increases risk of adverse effects. For example, the UL for vitamin D is 4,000 IU/day, and for zinc it is 40 mg/day. We flag products that could lead to exceeding the UL at recommended doses.
USP Verified
The United States Pharmacopeia has independently verified that the product contains the ingredients listed on the label in the declared amounts, is free from harmful contaminants, and was made under GMP conditions. USP is one of the two gold-standard certifications we look for. Products with USP verification receive a significant boost in our quality score.
W
Withanolides
The primary active compounds in ashwagandha. Most clinical trials use extracts standardized to specific withanolide percentages. KSM-66 is standardized to 5% withanolides, while Sensoril is standardized to 10% (but at a lower total dose). The withanolide content and the specific extract used determine whether an ashwagandha product matches what was studied in RCTs.