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Breast milk is always healthier for baby than infant formula, but not all breast milk is created equal: studies show that a mother’s diet determines the amount and kinds of fat in her milk.

Babies need fat, both saturated and unsaturated. It is essential for growth, especially for the development of the nervous system and of the brain, which is 60-per-cent fat. Particularly important for infant brain development are essential fatty acids (EFAs). We often praise human milk for being a good source of EFAs, but the amount in human milk depends on the mother’s diet. A nursing mother who consumes healthful fats such as cold-pressed sunflower oil, flax seeds, fish oils, and eggs makes breast milk that contains sufficient amounts of omega-3 and omega-6 essential fatty acids.

A 1999 study in the scientific journal Lipids showed that breast milk could have a very wide range of fat content. Depending on their mothers’ diet, some babies get two-per-cent milk, and others get up to nine per cent, the equivalent of table cream. Which babies are getting better nutrition? Lactating women on high-carbohydrate, low-fat diets have been found to experience a decrease in their milk fat levels, which is associated with infant neurological problems and failure to thrive.

The Importance of Essential Fatty Acids

Two essential fatty acids (EFAs) vital to infants’ development are DHA (docosahexaenoic acid) and AA (arachidonic acid). DHA can be derived from the alpha-linolenic acid (omega-3) found in flax seed oil or eaten directly in the form of fish oil. AA can be derived from linoleic acid (omega-6) from sunflower oil, butter, and eggs.

A nursing mother who consumes these healthful fats makes breastmilk containing sufficient amounts of omega-3 and omega-6 EFAs, which are critical to the process of myelination, (the development of the sheath around nerve fibres that enables them to send messages). A 2001 study in Acta Pediatrica found that higher blood levels of DHA and AA were associated with better visual and cognitive development in infants. These special fats accumulate in the brain and retina. If they are absent in the diet, the child is likely to suffer from learning disabilities and vision problems.

Failure to thrive is another potential impact of inadequate amounts of EFAs, according to the Infant Feeding Action Coalition (Infact Canada), a non-profit organization that promotes breastfeeding for the health and well-being of infants. Low reserves of essential fatty acids at birth will be further compromised if the infant is artificially fed or if the breastfeeding mother’s diet lacks EFAs.

Another study in Lipids (1997) compared the fatty acid composition of milk from mothers in two Chinese provinces with that of Canadian mothers and correlated it to the fatty acids in their diets. Breast-milk levels of AA and DHA in Chinese mothers were much higher than those of Canadian mothers.

The Dangers of Trans Fats

How healthful is Canadian breast milk? Because a mother’s diet determines what kind of fat is in her milk, breast-milk fat from a mother who consumes processed foods such as donuts, crackers, margarine, and French fries is made up of these damaging trans fats. Recent studies suggest Canadians have a higher intake of trans fats than other populations. The study comparing Chinese and Canadian breast milk also found Canadians had 33 times more trans fats in their milk than the Chongqing mothers, who did not consume processed foods.

Research in the New England Journal of Medicine shows that trans fats increase the risk of heart disease. They also create further problems by interfering with other fatty acids. A compelling reason to avoid trans fats is that they replace EFAs such as DHA and AA. Even if a mother consumes these “good” fats, trans fats will displace them in her milk and in her baby’s body. Trans fats were found to make up from seven to 17 percent of Canadian women’s breast-milk fat.

Kerstin Peterson is a freelance writer and editor in Prince George, BC. As coordinator of the Association for the Improvement of Maternity Services in BC (AIMS BC), she works to promote woman-centred care. She can be reached at info@aimsbc.org.

Source: alive #258, April 2004