Swanson · BCAA · Capsules
Is Swanson BCAA underdosed?
Verdict
1.02 g per servingone dose · studies use 2–3 g of l-leucine
Below research doseOne serving contains 1.02 g; studies use 2–3 g in one dose. The label's directions allow 1 serving a day.
One capsule gives 340 mg, so reaching the low end of what studies use (2 g) takes 5.9 capsules at once; it ranks 15th of 23 BCAA supplements here by dose.
To reach the research dose. It would take 6 capsules at once (2.04 g) to reach the 2 g studies use, more than the label's directions, which allow 3 capsules (1 serving a day).
Amino acids, one by one
BCAAs are three of the nine essential amino acids, and this label lists no others (no lysine, threonine, phenylalanine, methionine, histidine or tryptophan). The ISSN's 2018 review advises all nine: in the study it describes, BCAAs alone raised muscle protein synthesis less than whey protein giving the same BCAAs.
| Amino acid | In one serving | In 10 g at the WHO pattern | Share |
|---|---|---|---|
| Leucine | 1.02 g | 2.12 g | Below · 48% |
| Isoleucine | 513 mg | 1.09 g | Below · 47% |
| Valine | 513 mg | 1.41 g | Below · 36% |
| Lysine | — | 1.63 g | Not listed |
| Threonine | — | 815 mg | Not listed |
| PhenylalanineWHO figure: phenylalanine + tyrosine | — | 1.36 g | Not listed |
| MethionineWHO figure: methionine + cysteine | — | 815 mg | Not listed |
| Histidine | — | 543 mg | Not listed |
| Tryptophan | — | 217 mg | Not listed |
How this works: the WHO's adult requirement for each essential amino acid (WHO/FAO/UNU 2007, Table 23), scaled to a 10 g dose, the low end of the 10–12 g of essential amino acids in one dose in the ISSN's 2018 review. No study gave these amino acids one at a time at these amounts: it shows how a serving's mix compares with what the body needs, not a dose of each. The WHO figures for methionine and phenylalanine include cysteine and tyrosine, which the body can make; tyrosine is counted when the label lists it. Salt forms are counted as the amino acid in them (lysine hydrochloride as 80% lysine), and a DL form as half L.
What the label says
- L-Leucine per serving
- 1.02 g in 3 capsules
- Servings a day
- 1 serving a day
- L-Leucine a day, as directed
- 1.02 g
- Research dose
- 2–3 g Evidence: Moderate
Suggested use: As a dietary supplement, take three capsules per day with water.
Also on the label
| Ingredient | Per serving | Verdict |
|---|---|---|
| Vitamin B6 (Pyridoxine Hydrochloride) [USP] | 8 mg | Not graded |
More about l-leucine: forms, timing and the studies behind the dose.
Same category, compared
All 23 BCAA supplements we checked, ranked by dose (commission never changes the order). Studies use 2–3 g of l-leucine; servings counted to 2 g.
Where the reference doses come from
- L-Leucine, 2–3 g: Jäger et al., 2017; Kerksick et al., 2018.
- The amino-acid balance: the adult requirement pattern in WHO/FAO/UNU, 2007, Table 23.
- Label data: National Institutes of Health, Office of Dietary Supplements. Dietary Supplement Label Database, 2026. https://dsld.od.nih.gov/. Label 308485, including its servings a day.
For a supplement taken as one dose we judge one serving, and show the most the label allows in a day. Read the full methodology or the corrections log.