Supplement Glossary

Short, honest definitions of terms that come up often on supplement labels and product pages. No firm medical claims; where the evidence is uncertain, we say so.

Protein Types

Whey Concentrate (WPC): The most common and usually cheapest type of protein powder, made from whey. Typically 70-80% protein, with small amounts of fat and lactose. See prices →
Whey Isolate (WPI): Whey concentrate put through an extra filtration step. Protein rises to 85-95% and lactose drops to almost zero, so it is a common choice for people with lactose sensitivity. See prices →
Hydrolyzed Whey (WPH): Whey whose protein is partly broken down in advance, in theory absorbed faster. Usually more expensive; for most users the practical difference from isolate or concentrate is small. See prices →
Casein: The second main milk protein, digested much more slowly than whey. Usually taken before bed or for long gaps between meals rather than for quick post-workout recovery. See prices →
Plant Protein: Protein powder from sources such as pea, rice, hemp or soy, with no dairy. A single plant source often has an incomplete amino acid profile, so good products blend several. See prices →

Amino Acids

BCAA: The three branched-chain amino acids (leucine, isoleucine, valine), focused on the leucine signal that triggers muscle protein synthesis. A subset of the EAAs. See prices →
EAA: All nine essential amino acids the body can't make itself (the three BCAAs are among them). Building muscle protein needs the other eight, not just the leucine signal. See prices →
Glutamine: An amino acid linked to immune and gut health. Its direct effect on muscle growth is not as well supported as BCAAs or EAAs. See prices →
Citrulline: An amino acid that supports blood flow and adds to the "pump" during training. Effective doses are usually around 6-8 g of citrulline malate; many budget products use less. See prices →
Beta-Alanine: An amino acid that raises carnosine in muscle and can help delay fatigue in short, high-intensity efforts. Tingling of the skin (paresthesia) is a harmless, well-known side effect. See prices →
Taurine: An amino acid found in energy drinks and some pre-workouts. Its effect on performance is less well supported than ingredients such as caffeine or beta-alanine. See prices →
ALCAR (Acetyl-L-Carnitine): A form of L-carnitine thought to cross the blood-brain barrier more easily than standard L-carnitine. Also mentioned for cognitive effects, where evidence is limited too. See prices →

Performance Supplements

Creatine Monohydrate: The oldest, most researched and usually cheapest form of creatine. Its effect on strength and power is among the best supported of any supplement. See prices →
Creatine HCl: Creatine hydrochloride, marketed as causing less water retention or stomach upset. Far fewer large studies support those claims than support monohydrate. See prices →
Loading Phase: Taking a high dose of creatine (about 20 g a day) for the first 5-7 days to fill muscle stores quickly. Skipping it and starting at a low dose reaches the same saturation within 3-4 weeks; loading is only about speed. See prices →
Thermogenic: Ingredients thought to raise metabolic rate slightly and briefly (caffeine, green tea extract). The effect is tiny next to a daily calorie deficit and doesn't cause fat loss on its own. See prices →
Electrolytes: Minerals such as sodium, potassium and magnesium that help regulate fluid balance and muscle function. Sodium is the one lost in the largest amounts in sweat. See prices →
Bioavailability: How much of a nutrient the body can actually use. The total amount on a label (e.g. "24 g protein") doesn't tell the whole story.

Weight Gain

Mass Gainer: A high-calorie supplement with far more carbohydrate than a standard protein powder, designed to make gaining weight easier. Usually unnecessary for people who gain weight easily. See prices →
Maltodextrin: A fast-digesting carbohydrate common in gainers. It can spike blood sugar; some better products use slower sources such as oats instead. See prices →

Vitamins and Minerals

Multivitamin: A supplement with many vitamins and minerals at low to moderate doses to help prevent general gaps. It doesn't target a specific deficiency; for one found in a blood test, a single, higher-dose supplement is usually more effective. See prices →
ZMA: A combination of zinc, magnesium and vitamin B6, claimed to support sleep and recovery. Evidence for those claims is limited. See prices →
Daily Value (%DV): The percentage of a reference daily intake that one serving provides, shown on the Supplement Facts panel. Useful for comparing how much of each ingredient a product really contains. See prices →

Fat Burners

CLA (Conjugated Linoleic Acid): A fatty acid found naturally in meat and dairy, said to affect fat storage. Results in human studies are inconsistent. See prices →
L-Carnitine: A compound that carries fatty acids to the part of the cell that produces energy. The body already makes enough, and the effect of extra supplemental carnitine is more modest than expected. See prices →

Prices and Labels

Price per Serving: The package price divided by the number of servings in it, the real cost. A big tub can look "cheap" and still cost more per serving.
Amino Spiking: The practice of adding cheap free amino acids (such as glycine or taurine) to inflate the protein number on the label. Third-party testing helps catch it.
Proprietary Blend: A label listing that gives the total weight of a group of ingredients but not the dose of each. It makes it impossible to tell whether an ingredient is present at an effective amount.
Third-Party Testing: Testing by a lab independent of the manufacturer that a product contains what the label says and no banned substances. NSF Certified for Sport and Informed Sport are well-known programs.
Real Price Drop (WheyProof definition): A product whose current price is genuinely below its highest price in the last 30 days. It rests on the price history we collect, not on the store's own "was/now" claim; WheyProof shows the two separately as "Real price drops" and "Store sales".