Breast Milk TFAs Measured by GC-MS

While breast milk is considered the best food for babies during their first 6 months of life, it can contain trans fat acids (TFAs), and these can get in the way of the body making certain healthy fats that babies need, which may raise the chances of problems like asthma or eczema. The body cannot make TFAs on its own; they only come from what a mother eats. Because of this, the amount of TFA in breast milk could give us a good idea of how much TFA a breastfeeding mother has recently eaten. But studies do not agree on exactly how a mother's diet connects to the TFA levels found in her milk. On top of that, since food generally contains less TFA than it used to, the Craig-Schmidt formula, an older method used to estimate TFA levels in diet or breast milk, doesn't seem to work reliably anymore.

This led to a study aiming to check whether the level of TFA in breast milk can be used to show how much TFA a breastfeeding mother has recently eaten. The researchers also tried to get a rough, early sense of exactly how diet and breast milk are numerically related. The measurement of the fats, including TFAs, was determined by gas chromatography-mass spectrometry (GC-MS). A paper based on this work was published in the journal Nutrients.¹

What Factors Influence the Composition of Breast Milk, and Where Do Its Fats Come From?

The World Health Organization (WHO) recommends that babies be fed only breast milk for their first six months and then continue breastfeeding through their second year of life or beyond, for as long as both mom and baby want to keep going.² Breast milk has everything a baby needs nutritionally, adjusts to meet those needs as the baby grows, and helps ensure healthy growth and development.³

Many things can affect what is in breast milk, including the woman’s age, how many times she has given birth, how long her pregnancy lasted, how long she has been breastfeeding, the time of day she is feeding, any infections or metabolic conditions she has, and any medications she might be taking. The biggest factors by far, however, are what a woman eats and her overall nutrition before, during, and after pregnancy, especially when it comes to the fat content of her milk. The fats in breast milk come from three places: fats the body makes on its own in the breast tissue, fats stored in body fat and the liver, and fats that come directly from what the mother eats.⁴

Breast milk can contain TFAs, a specific type of fat, structurally different from the more common "healthy" fats, and this molecular structure is what makes them behave differently in the body.⁵ Research has linked TFAs to a variety of health problems, including heart disease, cancer, and type 2 diabetes.^6-8

Can TFA Levels in Breast Milk Be Used to Estimate What a Breastfeeding Mother Recently Ate?

For this study, one breastfeeding mother took part, giving 10 samples of her breast milk along with 10 records of everything she ate that day, which were pieced together using a 24-hour diet survey. Her daily TFA intake ranged from 0.11 to 0.54 grams per day, while the TFAs found in 100 mL of her breast milk ranged from 0.02 to 0.07 grams. The more TFAs she ate, the more showed up in her milk, a clear, statistically meaningful link. From this, the researchers worked out some early formulas describing how a mother's TFA intake relates to the amount in her breast milk.¹

“This single-participant pilot study,” write the authors of the paper,¹ “suggests that TFAs content in breast milk may be a marker of the dietary intake of these compounds from the previous day. It seems that the dietary habits of breastfeeding mothers of twins are a significant factor influencing the composition of breast milk and, consequently, the nutritional quality of breastfed infants.”

That said, since the study only looked at one mother, the researchers believe that these results should be taken as a first, tentative step, not a firm conclusion, until they're tested in a larger group of mothers.¹

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References

1. Jasińska-Melon, E.; Mojska, H.; Bzikowska-Jura, A. Trans Fatty Acids Content in Breast Milk as a Marker of Their Short-Term Intake Within the Breastfeeding Mother's Diet: A Single-Participant Pilot Study. Nutrients 2026, 18 (13), 2177. DOI: 10.3390/nu18132177
2. WHO Recommendations on Newborn Health: Guidelines Approved by the WHO Guidelines Review Committee. World Health Organization website. 2017. https://iris.who.int/server/api/core/bitstreams/e3ae29ae-a7f2-47f8-b1ce-bed3e3b2a971/content (accessed 2026-03-06).
3. Lyons, K. E.; Ryan, C. A.; Dempsey, E. M. et al. Breast Milk, a Source of Beneficial Microbes and Associated Benefits for Infant Health. Nutrients 2020, 12 (4), 1039. DOI: 10.3390/nu12041039
4. Zhang, Z.; Wang, Y.; Yang, X. et al. Human Milk Lipid Profiles Around the World: A Systematic Review and Meta-Analysis. Adv Nutr. 2022, 13 (6), 2519-2536. DOI: 10.1093/advances/nmac097
5. European Union (EU). Regulation (EU) No 1169/2011 of the European Parliament and of the Council of 25 October 2011 on the provision of food information to consumers, amending Regulations (EC) No 1924/2006 and (EC) No 1925/2006 of the European Parliament and of the Council, and repealing Commission Directive 87/250/EEC, Council Directive 90/496/EEC, Commission Directive 1999/10/EC, Directive 2000/13/EC of the European Parliament and of the Council, Commission Directives 2002/67/EC and 2008/5/EC and Commission Regulation (EC) No 608/2004 Text with EEA relevance. Off. J. Eur. Union 2011, 304, 18–63.
6. Reynolds, A.; Hodson, L.; de Souza, R. et al. Saturated Fat and Trans-Fat Intakes and Their Replacement with Other Macronutrients. A Systematic Review and Meta-Analysis of Prospective Observational Studies. World Health Organization website 2022. https://iris.who.int/server/api/core/bitstreams/a21e2dfc-2980-429f-a1ea-ad92055b377f/content (accessed 2026-03-05).
7. Kim, Y.; Je, Y.; Giovannucci, E. L. Association Between Dietary Fat Intake and Mortality from All-Causes, Cardiovascular Disease, and Cancer: A Systematic Review and Meta-Analysis of Prospective Cohort Studies. Clin Nutr. 2021, 40 (3), 1060-1070. DOI: 10.1016/j.clnu.2020.07.007
8. Wendeu-Foyet, G.; Bellicha, A.; Chajès, V. et al. Different Types of Industry-Produced and Ruminant Trans Fatty Acid Intake and Risk of Type 2 Diabetes: Findings from the NutriNet-Santé Prospective Cohort. Diabetes Care 2023, 46 (2), 321-330. DOI: 10.2337/dc22-0900