The purpose of this project is to study the effect of dietary supplementation with a natural health product (NHP) with a focus on its effects on its levels in breast milk.

The effect of oral cysteine on its levels in breast milk and plasma will be measured in breast feeding mothers.

The investigators will not be studying tryptophan and tyrosine in this study. The title is an overview title left over from other past studies (but the investigators are only assessing cysteine at this time).

Inclusion Criteria:

• Subjects would be healthy mothers who are breastfeeding at the moment, but plan to stop at the time of study
• The subject, as reported, should be in a good health
• The subject is not taking any medication
• The subject is not taking any investigational medicinal product within 8 weeks prior to dosing
• The subject does not have any known hypersensitivity to components in the proposed treatment
• The subject does not have a history of severe drug allergy or drug hypersensitivity

Other general medical requirements for inclusion:

• Age 18 to 45
• BMI 19 to 40 (kg/m2)
• Resting pulse between 45 and 100 bpm
• Systolic blood pressure between 91 and 139 mmHg (inclusive)
• Diastolic blood pressure between 51 and 90 mmHg (inclusive)
• Orthostatic blood pressure change <20 mmHg (based on the difference between supine and standing (1 minute) systolic blood pressure)
• The subject is in good health based on their report and answer to general health questionnaire

Exclusion Criteria:

• The subject has taken any investigational medicinal product within 8 weeks prior to dosing
• The subject is pregnant (based upon urine pregnancy test at time of screening and day of supplement intake)
• The subject has known hypersensitivity to components in the proposed treatment or to related compounds
• The subject has a history of severe drug allergy or drug hypersensitivity involving an anaphylactic reaction i.e. shortness of breath and/or reduced blood pressure
• Subjects who are smoking more than one package of cigarette per day will be excluded from the study
• The subject decides to breastfeed the infant on the study day