Lysine Intake for Breastfeeding

Overseen By Taylor Bailey, BSc

Age: 18 - 65

Sex: Female

Trial Phase: Academic

Sponsor: University of British Columbia

Must not be taking: Estrogen, Anti-dopaminergic, Methyldopa, others

Disqualifiers: Metabolic, Cardiovascular, Neurological, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 2

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial examines the lysine requirements of breastfeeding mothers, focusing on those exclusively breastfeeding 3-4 month-old infants and those with 9-10 month-old infants beginning solid foods. Participants will consume shakes with varying lysine levels, and researchers will assess how effectively their bodies utilize these proteins. Healthy women breastfeeding a single child, either exclusively or with some solid food, are suitable candidates for this study. As an unphased study, this trial allows participants to contribute to valuable research that could enhance nutritional guidelines for breastfeeding mothers.

Will I have to stop taking my current medications?

Yes, you will need to stop taking medications that affect lactation or any continuous prescription medication to participate in this trial.

What prior data suggests that lysine intake is safe for breastfeeding women?

Research suggests that lysine supplements are likely safe for breastfeeding mothers. Studies have found no evidence that lysine harms breastfeeding infants. However, information about the safety of lysine for pregnant or breastfeeding women remains limited. Another source indicates that lysine is generally safe and poses no risk during breastfeeding.

Specific safety data for lysine given as an infusion (through a needle into a vein or muscle) is unavailable, but no negative effects have been reported from lysine supplements during breastfeeding. Overall, lysine appears to be well-tolerated. Participants should discuss any concerns with their healthcare provider before joining the trial. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Unlike standard treatments for breastfeeding nutrition, which typically focus on general dietary guidelines, this new approach explores the specific supplementation of lysine, an essential amino acid. Researchers are excited about this treatment because lysine intake could directly influence milk production and quality, offering a more tailored solution for breastfeeding mothers. By adjusting lysine levels, this treatment could provide insights into optimizing nutritional support during breastfeeding, potentially enhancing infant growth and maternal health in a more precise way than current broad-spectrum dietary recommendations.

What evidence suggests that lysine intake is effective for breastfeeding?

Research shows that lysine is important for breastfeeding mothers because it aids in milk production. Increasing lysine intake during breastfeeding can boost key nutrients, like proteins, in breast milk. Studies have also found that insufficient lysine can affect a mother's metabolism and hormone levels, crucial for her health and successful breastfeeding. As an essential amino acid, lysine must be obtained from food since the body cannot produce it. This trial will test various lysine intake levels, from deficient to excess, to evaluate their impact on breast milk quality and breastfeeding outcomes. These findings suggest that adjusting lysine intake could enhance breast milk quality and support better breastfeeding outcomes. ^{1 6 7 8 9}

Who Is on the Research Team?

Rajavel Elango

Principal Investigator

University of British Columbia

Are You a Good Fit for This Trial?

This trial is for women who are exclusively breastfeeding a single infant aged 3-4 months. It's also for those same mothers when their infants transition to complementary feeding at 9-10 months. Participants must be healthy with no dietary restrictions that could affect the study.

Inclusion Criteria

My baby is 9-10 months old and has started eating solid foods.

I am a healthy woman aged 20-40, exclusively breastfeeding a 3-4 month old baby.

Exclusion Criteria

I do not have serious health issues like heart, nerve, or immune system problems.

I have had breast surgery that could affect breastfeeding.

I am taking medication that could affect breastfeeding.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1 hour

1 visit (in-person)

Study Day

Participants receive a test lysine intake ranging from deficient to excess, with diets provided in a complete protein shake format. Breath, urine, and blood samples are collected to assess lysine metabolism.

8 hours

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after each study day

1-2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Lysine

Trial Overview

The study is testing different levels of lysine, an important amino acid, in the diets of breastfeeding women. Using protein shakes with varying lysine content, researchers will measure how this affects protein synthesis and nutrition during lactation and after introducing solid foods to infants.

How Is the Trial Designed?

Group I: Test Lysine Intake Experimental Treatment 1 Intervention

Randomly assigned one of 7 test lysine intakes that range from deficient to excess (12mg/kg/d to 84mg/kg/d). Participants may complete up to 4 study days, at different randomly assigned intakes.

Who Is Running the Clinical Trial?

University of British Columbia

Lead Sponsor

Trials

1,506

Recruited

2,528,000+

Canadian Institutes of Health Research (CIHR)

Collaborator

Trials

1,417

Recruited

26,550,000+

Published Research Related to This Trial

L-lysine (Lys) significantly enhances cell viability and milk protein synthesis in bovine mammary epithelial cells (BMECs), with optimal concentrations (1.0 mmol/L) increasing cell viability by 17-47% and protein synthesis by 7-23%.

Lys promotes protein synthesis primarily by increasing the uptake through the ATB0,+ transporter and activating the mTOR and JAK2-STAT5 signaling pathways, indicating its critical role in amino acid nutrition for milk production.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Lysine Stimulates Protein Synthesis by Promoting the Expression of ATB0,+ and Activating the mTOR Pathway in Bovine Mammary Epithelial Cells. Lin, X., Li, S., Zou, Y., et al.[2023]

In a study involving lactating Holstein cows, increasing L-lysine infusion levels led to a linear increase in milk production and milk protein yield, indicating that lysine is a key amino acid for enhancing milk output.

The research estimated that to meet the lysine requirements for cows producing about 30 kg of milk daily, an additional 64 g of L-lysine per day is necessary, highlighting the importance of lysine in dairy cow nutrition for optimal milk production.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

An assessment of absorbable lysine requirements in lactating cows. King, KJ., Bergen, WG., Sniffen, CJ., et al.[2018]

Lactating women showed a slower rate of protein turnover and lower lysine catabolism compared to non-lactating postpartum women, indicating metabolic adaptations during lactation.

The study suggests that an intake of 1.3 g protein/kg per day may be insufficient to meet the protein needs of lactating women, potentially affecting overall maternal protein metabolism.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Lysine and protein metabolism in the young lactating woman. Thomas, MR., Irving, CS., Reeds, PJ., et al.[2013]

Lysine uptake in the lactating rat mammary gland is time-dependent and can be inhibited by both cationic amino acids (like arginine and ornithine) and various neutral amino acids (such as methionine and leucine), indicating a complex interaction between different types of amino acids.

Cationic amino acids not only inhibit lysine uptake but also enhance its efflux from mammary tissue, suggesting that they may share a common transport mechanism that regulates lysine levels in the gland.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Lysine transport in lactating rat mammary tissue: evidence for an interaction between cationic and neutral amino acids. Shennan, DB., McNeillie, SA., Jamieson, EA., et al.[2013]

The study used a rapid, paired-tracer dilution technique to investigate how lysine is transported across the mammary epithelium in lactating rats, revealing that lysine transport is likely mediated by specific carriers influenced by extracellular lysine concentration.

Lysine uptake was inhibited by the presence of other amino acids like leucine and glutamine, suggesting that the transport system in the mammary tissue can also accept neutral amino acids, which may impact nutrient availability during lactation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Evidence for an interaction between cationic and neutral amino acids at the blood-facing aspect of the lactating rat mammary epithelium. Calvert, DT., Shennan, DB.[2019]

Citations

1.

ncbi.nlm.nih.gov

ncbi.nlm.nih.gov/books/NBK615801/

Lysine - Drugs and Lactation Database (LactMed®) - NCBI

The total lysine content of milk averages 915 mg/L in the first month postpartum and decreases to an average of 622 mg/L in month 6 postpartum.[ ...

2.

pubmed.ncbi.nlm.nih.gov

pubmed.ncbi.nlm.nih.gov/18547756/

Effects of lysine intake during late gestation and lactation ...

Higher lysine intake during lactation increased the concentrations of total solids (P=0.024), protein (P=0.001) and solids not-fat (P=0.042) in colostrum and ...

3.

nature.com

nature.com/articles/s41430-025-01588-z

Evaluation of the effect of different diets applied to ...

This study aimed to elucidate the relationship between maternal nutrition and the quantity and composition of breast milk.

4.

wcds.ualberta.ca

wcds.ualberta.ca/wcds/wp-content/uploads/sites/23/2018/02/Yang_etal_2000_36.pdf

Effects of dietary lysine intake during lactation on blood ...

A number of studies have demonstrated that low di- etary lysine intake during lactation affects metabolic state, LH secretion, and weaning-to-estrus interval ( ...

5.

sciencedirect.com

sciencedirect.com/science/article/abs/pii/S1871141317301312

Energy and lysine requirements and balances of sows ...

At peak lactation, 95% and 72% of total required SID lysine and ME, respectively, were associated with milk production (including oxidation). Relative to day ...

6.

reference.medscape.com

reference.medscape.com/drug/l-lysine-lysine-monohydrochloride-lysine-344603

Lysine (Herb/Suppl)

Lactation: avoid use. Pregnancy Categories. A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk. B: May be acceptable ...

7.

ncbi.nlm.nih.gov

ncbi.nlm.nih.gov/books/NBK501922/

Drugs and Lactation Database (LactMed®) - NCBI Bookshelf

The LactMed® database contains information on drugs and other chemicals to which breastfeeding mothers may be exposed.

8.

vinmec.com

vinmec.com/eng/blog/what-is-lysine-benefits-and-side-effects-en

What is Lysine? Benefits and Side Effects

Side Effects of Lysine​​ Currently, there is insufficient reliable information about the safety of lysine for pregnant or breastfeeding women. ...

9.

nervanamedical.com

nervanamedical.com/service/iv-im-therapy/im-iv-additives/l-lysine-iv-or-im/

L-Lysine (IV OR IM)

There is no evidence indicating ill effect from lysine supplementation during breastfeeding. No specific safety data for L-lysine hydrochloride infusion could ...