A recent small study confirms what many nursing mothers already suspect - that what the mother eats has an effect on the flavor of breast milk. There has been a lot of anecdotal evidence of the taste of breast milk varying depending on foods eaten, but not much evidence. Earlier studies did find a taste effect from some foods (e.g. carrots, garlic), but not others.
Researchers at the Technical Univ. of Munich investigated whether dominant tastes of a curry dish (red chili, pepper, ginger) were transferred to the breast milk of 16 nursing mothers. They found that one hour after eating a curry dish, the breast milk of nursing mothers contained piperine (from pepper), but not substances from red chili and ginger. And it was still there in breast milk produced hours later.
Interestingly, while the researchers thought that even though the piperine could be detected with laboratory instruments, they doubted it could be tasted by infants. Hmm.. don't know if infants would agree. Humans are incredibly sensitive to tastes and odors. It is thought that early exposure to all sorts of different smells and tastes could have an effect on later food preferences.
Because only piperine (from pepper) was detected and not the other chemicals they looked for (curcumin, capsaicin, 6-gingerol, etc.), the researchers hypothesize that there is a barrier between the mother's circulation and the mammary glands - which only some compounds can cross (such as piperine). This would be comparable to the blood-brain barrier (BBB), which regulates and restricts compounds from getting to the brain.
They point out that caffeine and piperine both can cross the blood-brain barrier, and both have been shown to get into breast milk. [By the way, studies show other compounds also appear in breast milk such as lycopene (from tomatoes).] Bottom line: Eat a variety of foods when nursing.
From Science Daily: Spicy breast milk?
Breast milk is the first food that babies consume. Various studies have suggested that the "taste experience" in early childhood influences eating behavior in adults. Unlike standardized infant formula, natural milk does not taste and smell the same every day. The differences are largely due to the maternal diet.
However, the taste and aroma of food consumed by the mother are not transferred one-to-one to her milk. Research has already shown that odor and taste active substances from garlic or coffee partly enter the mother's milk as an odor active metabolic product, while flavors from fish oil or nursing tea were of little to no significance in this respect.
The extent to which pungent substances from chili, ginger, or pepper are found in breast milk has been even less researched than aroma and taste substances. For this reason, a scientific team led by TUM has now investigated whether these substances are transferred from food to breast milk and if so, which ones.
Through extensive mass spectrometric analyses, the team has shown that already one hour after consumption of a standardized curry dish, piperine is detectable in breast milk for several hours. "The observed maximum concentrations of 14 to 57 micrograms per liter were about 70- to 350-fold below the taste perception threshold of an adult," says Professor Corinna Dawid, who heads the Chair of Food Chemistry and Molecular Sensory Science at TUM commissarial for Professor Thomas Hofmann.
Roman Lang, who was initially involved in the study as a scientist at TUM and later at the Leibniz Institute for Food Systems Biology (LSB) adds, "It seems rather unlikely to us that the infants consciously perceive the sharpness. Nevertheless, it is conceivable that regular, low-threshold activation of the "pungent receptor" TRPV1 could help to increase tolerance for such substances later on."
Pungents from ginger or chili as well as the secondary plant compound curcumin, which is also abundant in curry, did not enter milk, according to the research. "We were particularly surprised by the latter, since piperine is supposed to significantly increase the bioavailability of curcumin according to the results of other studies," reports Roman Lang, who heads the Biosystems Chemistry & Human Metabolism research group at the LSB.