PolyU research discovers the impact of fruit and vegetable intake on the nutritional value of breast milk

The breastfeeding rate in Hong Kong has been increasing steadily over the past 20 years. As the source of a variety of nutrients, breast milk plays a vital role in the healthy growth and development of infants. The Research Institute for Future Food (RiFood) of The Hong Kong Polytechnic University (PolyU) has conducted a study to analyse the three-day dietary records and breast milk samples of Hong Kong lactating women. The research has revealed that the fruit and vegetable intake of lactating women was below the recommended level, and there was a significant correlation between dietary intake and the nutrient levels of breast milk, especially the carotenoid and polyphenol contents.

As explained by the research team, the first 1,000 days from pregnancy to a two-year-old infant is the basis for establishing long-term health. Breast milk contains a variety of nutrients and plays an important role in their healthy growth.

Prof. WONG Man-sau, Steering Committee Member of RiFood and Professor of the Department of Applied Biology and Chemical Technology of PolyU said, “Apart from commonly known nutrients, such as protein and fatty acids, breast milk also contains phytonutrients such as carotenoids and polyphenols. These phytonutrients are important in the physical development of infants and can reduce the level of inflammation. Lacking one or more nutrients may weaken the immune system of infants, and may also increase their risk of getting chronic diseases in the future.”

The PolyU research team collected breast milk samples and a three-day dietary record of about 90 lactating women and analysed the levels of carotenoid and polyphenol content.

The study found that only 4% of lactating women had dietary habits that met the recommendation from the Department of Health to consume at least two servings of fruits and three servings of vegetables per day, or the recommended intake of vitamin A according to the “Chinese Dietary Reference Intake” which was established by the Chinese Nutrition Society. The level of carotenoids in breast milk was higher in lactating women who had a higher intake of fruits and vegetables. Dr Christine LI, Teaching Fellow of the Department of Applied Biology and Chemical Technology of PolyU, said some carotenoids can be converted to vitamin A to promote the development of infants’ brain, vision and immunity, and can also protect the retina from damage by strong light.

The research also found a significant correlation between the dietary habits in fruit and vegetable consumption of lactating women and the polyphenol content in their breast milk. Dr Daisy ZHAO, Assistant Professor of the Department of Applied Biology and Chemical Technology of PolyU, said polyphenol is a powerful antioxidant and anti-inflammatory compound, which can prevent cardiometabolic diseases and reduce the risk of bacterial infection.

Based on the research findings, Dr Kenneth LO, Assistant Professor of the Department of Applied Biology and Chemical Technology of PolyU, suggested lactating women should enhance the levels of carotenoids and polyphenols in breast milk through increasing their fruit and vegetable intake. Common dark green vegetables, including Chinese flowering cabbage, spinach, Chinese kale, Indian lettuce, sweet potatoes, carrots, pumpkins, papayas, mangoes etc., are rich in phytonutrients.

A new research project “Feeding mom feeding infants” has been launched by the research team, recruiting about 100 pairs of lactating women and infants for a one-year study, to further investigate the relationship between the dietary habits of lactating women and the nutrients of breast milk, gut microbiota composition of infants and their growth.

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