Alpine butter changes fatty acids in human milk
What it found
In 16 breastfeeding women, eating Alpine butter for 10 days changed the fatty acid and CLA pattern in their milk.
The main CLA isomer rose by about half.
What they found
Studies in people
CLA isomer increase
The main CLA isomer, c9,t11 18:2, increased by 49.7% during the butter phase. The total CLA content rose by 45.0%.
Other CLA isomers
Several other CLA isomers also rose significantly, including t11,c13 (up 100.5%), t6,t8 (up 67.3%), and t12,t14 (up 61.3%). Nine of the 14 detectable isomers showed no change and stayed below 5 mg per 100 g fat.
Saturated and trans fats
Butter increased the sum of saturated fatty acids by 2.057 g per 100 g fat and trans fatty acids (including CLA) by 0.178 g per 100 g fat. Polyunsaturated fats decreased.
Milk fat content
The total fat content of the milk did not differ between the butter and margarine phases.
Studies in people and animals
Newborn effects unknown
The authors note that only animal studies have looked at how CLA-rich milk affects newborn development, such as weight gain or allergy protection. They say human studies are needed.
What the authors conclude
“A breastfeeding mother can therefore modulate the FA/CLA supply of her child by consuming Alpine butter.”
Also in their conclusions
- They conclude that a breastfeeding mother can modulate the fatty acid and CLA supply of her child by consuming Alpine butter.
- They state that further studies will show whether human milk with this fatty acid and CLA isomer pattern acts as a functional food for newborns.
- They advise that further studies in humans are necessary to confirm potential effects on the newborn.
How it was done
The authors wanted to find out how the different CLA isomers in human milk change when mothers eat CLA-rich Alpine butter, since the pattern of these isomers was not known.
They ran a randomised cross-over trial in 20 healthy breastfeeding women, starting at day 20 after birth. The women ate either 30 g of Alpine butter or 40 g of margarine daily for 10 days, then switched to the other product for 10 days. Milk samples were taken on five days and analysed for fatty acids and CLA isomers.
What it can’t tell you
- This trial only measured fatty acids and CLA isomers in breast milk. It did not measure any health effects in the babies.
- The study lasted only 10 days per product, so it cannot show what happens with longer-term butter intake.
- The number of women was small (16 completed), so the results may not apply to all breastfeeding mothers.
Who paid
- Authors work at
- Zurich University Hospital, Switzerland
The paper
- Title
- Maternal dietary Alpine butter intake affects human milk: fatty acids and conjugated linoleic acid isomers
- Type
- Randomised controlled trial
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Bertschi I, Collomb M, Rist L, et al (2005). Maternal dietary Alpine butter intake affects human milk: fatty acids and conjugated linoleic acid isomers. Lipids. doi:10.1007/s11745-005-1419-8Free full textPubMed 16149737DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error