Quick answer

Few BCAA trials have enrolled women. In two of them, young women who took 0.1 g per kg before squats, and women who took 5 g a day for six months, reported less soreness than on placebo. In women after menopause, 9 g a day added nothing to 8 weeks of weight training.^1,2,3

Key facts

Only 2 of the 18 trials in a 2024 soreness analysis enrolled women alone.⁴
NIH notes that much supplement research is done in young men rather than women.⁵
US women eat about 69 g of protein a day on average, and complete protein is about 25% BCAAs.⁶
The upper safe intake for leucine was worked out in studies of men.⁶

Trials in women

Squats in untrained women. Twelve young women took BCAAs at 100 mg per kg of body weight, or a placebo, before 7 sets of 20 squats, then switched. Soreness peaked 2 to 3 days later either way, but was lower after the BCAA drink, and leg strength dropped less two days after the session.¹

Six months of lifting. In 100 recreational weightlifters, half of them women, 5 g a day in capsules for six months lowered soreness and fatigue ratings more than placebo, and the drop was larger in the women. Bench press gains were clearest in the men. It is a single trial, and its methods have not been checked beyond the abstract.²

Markers of muscle damage. In a crossover trial of 10 untrained women included in the 2024 analysis, 9 g of BCAAs did not change blood markers of muscle damage compared with placebo.⁴

Women after menopause. Thirty women did 8 weeks of supervised weight training with 9 g of BCAAs a day or a placebo, and a third group did no training. Muscle mass and strength rose in both training groups, with no difference between them, so the BCAAs added nothing measurable.³

Supplies leucine, isoleucine and valine, three essential amino acids that are building blocks of muscle protein*^6,7,8

Moderate evidence

That these amino acids are essential and are used to build muscle protein is established nutrition science. It is not evidence that this powder builds muscle or speeds recovery: the NIH says studies have not consistently shown that BCAA supplements enhance performance, build muscle or aid recovery, and the ISSN rates the evidence as limited or mixed.

Amount studied: Not tied to an amount: any food with complete protein supplies them

Amounts for a smaller body

Many trials set the amount by body weight. At 0.1 g per kg, the squat trial's amount, a 60 kg woman takes about 6 g. The soreness trials as a whole used 5 to 29 g a day, so a lighter person reaches a given per kg amount with less.^1,4

NIH says up to 20 g a day of BCAAs, split into doses, appears safe, and puts the upper safe intake of leucine alone at 500 mg per kg a day. That leucine figure comes from studies in young and older men.^5,6

Protein first

At the US average of 69 g of protein a day, a woman eating mostly complete proteins already takes in well over 10 g of BCAAs, plus the other essential amino acids that BCAAs alone lack. NIH notes the evidence is inconsistent that BCAA supplements add anything beyond enough high-quality protein.^5,6

BCAAs are found in meat, poultry, fish, eggs and dairy foods such as milk, and in plant foods eaten in combinations that together provide all the essential amino acids.^5,6,9

Pregnancy, nursing and other cautions

We found no trials of BCAA supplements in pregnancy. A review of amino acid supplements lists pregnancy and nursing among the situations where their suitability still needs study. Ask your doctor first if either applies.¹⁰

Do not take BCAAs if you have maple syrup urine disease⁹
Ask first if you have liver disease, diabetes, or a neurological or psychiatric condition¹⁰
Ask first if you take levodopa, because amino acids compete with it for absorption¹¹

Questions people ask

Are BCAAs good for women over 50?

The one trial in women after menopause found no added gain: 9 g a day during 8 weeks of weight training gave no more muscle or strength than placebo. Both training groups gained from the training itself.³

Do BCAAs work differently in women?

Too few trials exist to say. One six-month trial found a larger drop in soreness in women and larger strength gains in men, but it has not been repeated.²

Can I take BCAAs while pregnant or breastfeeding?

Ask your doctor first. We found no trials of BCAA supplements in pregnancy, and a safety review lists pregnancy and nursing among the situations that still need study.¹⁰

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Sources

*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 page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.