Amino Acid Supplements in Pregnancy, Children and Older Adults: Why Evidence Is Thin
Why safety evidence for amino acid supplements in pregnancy, children and older adults is thin, what the sources we read do and do not show, and when to ask a clinician first.
Content last updated . This page has not been medically reviewed.
Talk to a clinician or pharmacist before using one of these supplements in any of these life stages. This page is information, not advice. If a child may have swallowed supplements, call Poison Help at 1-800-222-1222 (US) and see Poisoning: what to do first and Poison help by country.
Evidence labels used: mixed, insufficient evidence, and Proper evidence not found (we looked and found nothing usable; this is not a finding of safety).
Summary table
| Group | What the sources we read found | Label |
|---|---|---|
| Pregnancy | Trials of food-based protein supplements exist; single amino acid capsules and powders are largely unstudied in healthy pregnancies. Arginine has been studied under supervision in high blood pressure of pregnancy. | Mixed / insufficient |
| Breastfeeding | Proper evidence not found in the FDA, NHS and review sources we read for single amino acid supplements. | Proper evidence not found |
| Children and teens | Reviews we read tested adults. Energy-drink-style products with stimulants are advised against by pediatric sources. | Insufficient (amino acids); advice against (stimulant products) |
| Older adults | Position papers address protein from food; single amino acid supplements in older people are mostly studied in small trials. Kidney function and medicines matter. | Insufficient |
Children and teens
- Metabolism differs. The FDA notes that children's metabolisms are unique and that at different ages they handle substances at different rates. [4]
- Amino acid supplements. The reviews we read on tolerability and upper levels tested adults. [1] For healthy children, Proper evidence not found (our PubMed searches on pediatric supplements and the FDA and NHS pages we read gave no single amino acid safety data for children).
- Stimulant products. The American Academy of Pediatrics (2011) concluded that caffeine and other stimulants in energy drinks have no place in the diet of children and adolescents. [10] The FDA repeats that medical experts advise against energy drinks for children and teens. [8] A 2023 position stand lists energy drinks and shots as not recommended for children aged 2 to 12. [9] See Pre-workout and energy drink blends.
- Medical use is different. Arginine, for example, has been used in preterm infants, which is a clinical setting and not a reason to give supplements to a healthy child. [7]
Read more: Protein powder for children, teens and picky eaters, Protein for children and teens and Children and teens.
Older adults
- Kidney function. The PROT-AGE position paper (2013) says older people with severe kidney disease (eGFR below 30, not on dialysis) may need to limit protein intake. [11] A review of amino acid supplements and the kidney found that arginine seems to have both beneficial and detrimental effects, and that glutamine has been linked to kidney changes in people with diabetic nephropathy. [12]
- Leucine. In older men, acute studies of high leucine intakes found blood ammonia rising above normal values, and the authors stress that these were acute diet studies. [13]
- What is not settled. PROT-AGE says evidence is not yet sufficient to support specific recommendations on protein quality, timing and other nutritional supplements. [11]
- Many medicines. The FDA suggests bringing a list of every supplement and medicine to health visits. [4] See Amino acid supplement and medicine interactions.
Read more: Protein for older adults and plant-based diets, Protein and sarcopenia, Sarcopenia and muscle loss, Multiple medicines, kidney function and supplement burden and Older adults.
Before surgery and when a condition is present
The FDA says a health care professional may ask you to stop dietary supplements two or three weeks before a procedure. [4] If you have liver, kidney or heart conditions, take medicines, or are in any group above, check with a clinician or pharmacist first. Product quality also matters: Quality testing and certifications.Frequently asked questions
Are amino acid supplements safe in pregnancy?
We cannot say they are. For most single amino acids, Proper evidence not found in the sources we read. A review of arginine in high blood pressure of pregnancy reported no teratogenic or lethal effects in its trials, which were in patients with a pregnancy blood pressure condition. [6] Ask your obstetric clinician before using any supplement.
Is protein powder the same as an amino acid supplement for pregnancy?
No. Cochrane found evidence on food-based protein supplements, with one trial linking high-protein supplementation to more small-for-gestational-age babies. [5] That is a different product from single amino acids. See the pregnancy protein powder page linked above.
Can children take amino acid supplements?
Proper evidence not found for healthy children in what we read. Pediatric guidance we found concerns energy drinks, which it advises against. [10] Talk to a pediatrician first.
Do older adults need more protein or amino acids?
Position papers address protein from food and set kidney caveats. [11] Individual amino acid supplements are less well studied, and kidney function and medicines matter. [12]
Do amino acid supplements have official upper limits?
A 2023 review says national health agencies have not set tolerable upper intake levels for amino acids. [1] That is why a clinician's advice matters more than a number on a label.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Pregnancy and breastfeeding
What trials looked at. A Cochrane review of 17 trials in 9,030 women examined education and food-based energy and protein supplements in pregnancy. [5] One trial of high-protein supplementation (505 women) was associated with a significantly increased risk of small-for-gestational-age babies, while two small trials of isocaloric protein supplementation (184 women) showed no significant effect on birthweight. [5] These were food supplements, not capsules of single amino acids, and they do not tell us about amino acid products. See Protein powder during pregnancy and breastfeeding.
Arginine. A systematic review of seven randomized trials (916 patients) assessed arginine in hypertensive disorders of pregnancy. Three studies reported some adverse effects, and no teratogenic or lethal effects were noted. [6] A separate review notes arginine has been used in vulnerable groups including pregnant women, preterm infants and people with cystic fibrosis, and says more data are needed to evaluate safety fully. [7] These were trials in people with a diagnosed pregnancy blood pressure condition. They are not an endorsement of buying arginine for yourself in pregnancy.
Tryptophan, 5-HTP, NAC, BCAAs, glutamine and others. Proper evidence not found in the sources we read for safety in pregnancy or breastfeeding. Stimulant-containing products are different: the FDA recommends pregnant people talk to a health care provider about caffeine [8], and a 2023 sports nutrition position stand does not recommend energy drinks or shots for people who are pregnant, trying to become pregnant or breastfeeding. [9] See Pregnancy and breastfeeding and Preconception, pregnancy and postpartum wellness.
References
- Elango R. Tolerable Upper Intake Level for Individual Amino Acids in Humans: A Narrative Review of Recent Clinical Studies. Adv Nutr 2023 (full text via PMC10334138). Read 2026-10-23.
- US Food and Drug Administration, Information for Consumers on Using Dietary Supplements. Read 2026-10-23.
- NHS (UK), Have a healthy diet in pregnancy. Read 2026-10-23.
- US Food and Drug Administration, Mixing Medications and Dietary Supplements Can Endanger Your Health (consumer update, 2022). Read 2026-10-23.
- Ota E et al. Antenatal dietary education and supplementation to increase energy and protein intake. Cochrane Database Syst Rev 2015. Read 2026-10-23.
- Gui S et al. Arginine supplementation for improving maternal and neonatal outcomes in hypertensive disorder of pregnancy: a systematic review. J Renin Angiotensin Aldosterone Syst 2014. Read 2026-10-23.
- McNeal CJ et al. Safety and Effectiveness of Arginine in Adults. J Nutr 2016. Read 2026-10-23.
- US Food and Drug Administration, Spilling the Beans: How Much Caffeine Is Too Much?. Read 2026-10-23.
- Jagim AR et al. International society of sports nutrition position stand: energy drinks and energy shots. J Int Soc Sports Nutr 2023. Read 2026-10-23.
- American Academy of Pediatrics, Committee on Nutrition and Council on Sports Medicine and Fitness. Sports drinks and energy drinks for children and adolescents: are they appropriate? Pediatrics 2011. Read 2026-10-23.
- Bauer J et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc 2013. Read 2026-10-23.
- Davani-Davari D et al. The Renal Safety of L-Carnitine, L-Arginine, and Glutamine in Athletes and Bodybuilders. J Ren Nutr 2019. Read 2026-10-23.
- Elango R, Rasmussen B, Madden K. Safety and Tolerability of Leucine Supplementation in Elderly Men. J Nutr 2016. Read 2026-10-23.