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Diet: How It Affects Mother's Milk

Breastfeeding mothers are often told not to eat foods such as cabbage and broccoli, which are high in fibre, and are known to cause gas, because they will give the baby gas, too. According to Lawrence ¹, there is no scientific basis for this recommendation. The normal bacteria in the mother’s intestines produce gas as they break down the fibre. It is not possible for either the fibre, or the gas, to enter the mom’s milk, or be transmitted to the baby in any way. The flavours, or scents, of these foods, however, can be absorbed from the mother’s gut, pass into the plasma, and then, into the milk. Occasionally a baby will not like this taste, and will be fussy at breast because of it.

As mammals, we teach our young what is safe to eat through our milk. The flavours and tastes of the mother’s diet are present in the amniotic fluid, and are experienced by the baby in the womb. Even before birth, the baby comes to know the food of his own culture. He continues to taste these foods as he drinks his mother’s milk. These are the foods most acceptable to him when solids are introduced after 6 months of age. If a mother has never eaten a particular food herself, her baby may not readily accept that food because theoretically, it is not a safe food to eat. Studies have shown babies prefer cereal mixed with carrot juice when their mothers have drunk carrot juice during lactation. ² Rat pups also will prefer weaning foods reflecting the flavours of their mother’s diet.³

Some flavours in the milk are stronger than others. Garlic, when not normally consumed by the mother, has been shown to result in babies suckling longer, and at a faster rate, at the next feeding. It would appear they find this new taste more interesting. This behaviour can lead to an increase in the mother’s milk supply. When babies have been exposed to garlic previously, they do not change their suckling pattern. It would appear they already know this flavour, and it is no longer a novel experience for them. Mint, vanilla, cheese, and alcohol flavours, as well as spices, are also easily detected in amniotic fluid and milk.⁴

Despite this research, some mothers have noted that their babies do react adversely when they eat certain foods. Some babies show colicky or fussy behaviour up to 24 hours after the mom has ingested certain fruits or vegetables.⁵ If the mother notes this occurrence on more than one occasion, she should avoid that particular food.

The chemical capsaicin, found in red peppers, would appear to be very quickly absorbed by mothers and passed into their milk. A perianal rash has been reported in breastfeeding babies whose mothers had consumed hot red peppers. This rash can occur within an hour, and last 12 to 48 hours.⁶

Foods and beverages consumed by the mother can also change the colour of her milk. Beets can give a pinkish tinge to the milk, as well as yellow and red food colourings, often found in sodas. Green milk has been seen when mothers consumed green coloured drinks or seaweed foods.⁷ Drugs can cause urine to be coloured brown, black, blue, green, or red, and presumably, they can have the same effect on milk.⁸

It is apparent that human milk gives the nursing baby a wonderful array of tastes and sensations which varies from feed to feed, and from day to day. It is sad to think that the formula-fed infant is missing this experience by having the same single taste for the first 6 months of his life. One wonders how this will affect the baby as he is given his first foods, and if his mammalian instinct to eat the same foods as his mother will be remembered from his in utero experiences.

1. Beers MH, Berkow R. The Merck Manual 17^th Edition. 1999. Merck & Co., Whitehouse Station, NJ.

2. Cooper RL, Cooper MM. "Red pepper induced dermatitis in breast-fed infants."

Dermatology. 1996;193(1):61-2.

3. Hudson R, Distel H. "The flavor of life: perinatal development of odor and taste preferences." Schweiz Med Wochenschr. 1999 Feb 6;129(5):176-81.

4. Lawrence RA, Lawrence RM. Breastfeeding: A Guide for the Medical Profession 5^th Edition. 1999. Mosby. New York.

5. Mennella JA, Jagnow CP, Beauchamp GK. "Prenatal and postnatal flavor learning by human infants." Pediatrics. 2001 Jun;107(6):E88

6. Mennella JA. "Mother's milk: a medium for early flavor experiences." J Hum Lact. 1995 Mar;11(1):39-45.

7. Mennella JA, Beauchamp GK. "Maternal diet alters the sensory qualities of human milk and the nursling's behavior." Pediatrics. 1991 Oct;88(4):737-44. Pediatrics. 1991 Oct;88(4):737-44.

 ⁷ Lawrence, p.327

Written by Joan M. Fisher, RN, BN, MEd, IBCLC
October 2002