Supplements glossary

The vocabulary that shows up on labels and in studies, explained once: from DIAAS to hepcidin, from proprietary blend to group A.

The terms that recur in this guide, on labels, and in any supplementation study. Training terms are in the training glossary and running ones in the runner’s glossary.

Categories and quality

Ergogenic aid

A substance or method that improves performance

Includes things that are not supplements, like heat or altitude.

Food supplement

A legal category: food, not medicine

It does not have to prove efficacy before being sold.

Group A / B / C / D

The AIS classification by level of evidence

A: use it. B: under study. C: no evidence. D: banned or risky.

Proprietary blend

A list of ingredients with a total and no breakdown

Makes the dose of each unknowable. A red flag.

Amino spiking

Adding free amino acids to inflate a protein assay

Raises measured nitrogen without adding complete protein.

Batch-by-batch certification

Independent testing of every batch against the banned list

Informed Sport, NSF Certified for Sport, Cologne List.

Protein and amino acids

DIAAS

The FAO protein quality score

It replaced PDCAAS. Above 1.0 means high-quality protein.

EAAs

The nine essential amino acids

The body cannot make them: they have to come from the diet.

BCAAs

Leucine, isoleucine and valine

Three of the nine. On their own they cannot sustain protein synthesis.

Leucine

The amino acid that fires the anabolic signal

Usual per-serving threshold: 2-3 g.

Muscle protein synthesis

The process of building protein in muscle

A few hours of elevation does not guarantee more muscle over months.

WPC / WPI / WPH

Whey concentrate, isolate and hydrolysate

They differ in filtration and price, not in outcome.

Performance

Phosphocreatine

The store that regenerates ATP in seconds

What supplemental creatine fills.

Loading phase

20 g/day for 5-7 days

Speeds up filling; does not change the end result.

Carnosine

The intramuscular buffer that beta-alanine raises

Buffers acidity in efforts of 30 s to 10 min.

Paraesthesia

The beta-alanine tingle

Harmless, and no indication that it is working today.

Dietary nitrate

A nitric oxide precursor

Beetroot juice. Antiseptic mouthwash cancels its effect.

CYP1A2

The enzyme that metabolises caffeine

Its variant explains much of the individual response.

Nutrition and micronutrients

Bioavailability

How much of what you swallow has an effect

The chemical form changes this a lot: oxide versus citrate, for example.

Ferritin

The marker of iron stores

Haemoglobin alone does not catch an early deficiency.

Hepcidin

The hormone that blocks iron absorption

It rises after hard exercise; hence taking iron away from training.

Glucose:fructose

A blend using two intestinal transporters

Lets you exceed the 60 g/h ceiling of glucose alone.

Exercise-associated hyponatremia

Low blood sodium from drinking too much

The serious risk in long events, not dehydration.

REDs

Relative energy deficiency in sport

Eating below expenditure on a sustained basis. No supplement compensates.