It is well known that breast milk exerts many positive effects on the general health, growth and development of infants. When breastfeeding is not possible, infant formula is considered to be an effective substitute to satisfy the regular nutritional demand of infants. At present, researchers make every effort to simulate the nutritional status of breast milk but mostly neglect the important role that odour plays in guiding the baby to recognize breast milk, promoting the baby's sucking behavior and food intake. The odour changes of the breast milk are so far mainly related to storage, lactational stage and maternal diet. To understand the odour characteristics of the human breast milk from different regions in China, 90 mothers will be recruited from three Chinese cities: Beijing, Chengdu and Wuxi, representing three typical regions with very different climate characteristics and diet habits. The breast milk samples as well as infant formulas will be analyzed using the identical state of the art separation and identification techniques to identify the odorous compounds, determine their concentrations in the breast milk and infant formula as well as determine their importance in contributing to the total odour of samples. The final objective of this study will be to mimic the odour of the breast milk and to understand the difference of breast milk odour from different regions with very different climate and diet composition, as well as to identify the odour deviation of the infant formula from the breast milk. Our results will provide references for the preparation of new infant formula with both nutritional ingredents and odour characteristics simulating that of breast milk.

Inclusion Criteria:

• Lactating mother aged 25 ~ 35 years
• Breastfeeding infants (aged 15 ~180 days) and express sufficient breast milk
• Mother is in good health and has balanced nutrition
• Mother is non smoker and non alcoholic, no smokers living in the same apartment
• Voluntarily signed the Informed Consent Form

Exclusion Criteria:

• Mother or newborn infant has major diseases
• Mother participating in any other nutritional or pharmaceutical intervention studies recently
• Other conditions that are not suitable for this study

Healthy lactating mothers (aged 25-35 years) who breast-feed their infants (aged 15-180 days).