Valio’s fat similarity index illustrates the benefits of milk fat in infant milk formula

Valio developed the fat similarity index to visualize the differences and similarities between fat sources in infant milk formula products, making comparisons easier.

Breast milk is the best choice when it comes to feeding infants and IMF products aim to imitate it as closely as possible to ensure babies have an optimal start in life. The many different fat compounds in breast milk have a beneficial impact on the growth and development of the infant, including brain development and gut health. Comparison between the benefits of different fat sources in IMF is difficult, but there is a way to compare them with only one number: the fat similarity index.

Comparing different IMF fat sources has been difficult due to the variety of fat compounds and the different properties they contain.

The fat similarity index is a simple indicator of fat composition

The similarity index *1 provides a simple way to compare the composition of infant formulas and breast milk.

When applied to the fat composition, the fat similarity index compares the similarities of milk fat and vegetable oils to fat compounds in breast milk with a numerical value *2 that is easy to compare.

Breast milk equals 1. The closer the index number is to 1, the more similar the fat composition is to that of breast milk.

The fat similarity index clearly shows that for commercially available milk-fat-based IMFs the index is significantly higher and closer to that of breast milk than the index of vegetable- oil-based IMF.

The science behind the fat similarity index

The new article “Similarity Index for the Fat Fraction between Breast Milk and Infant Formulas,” published in the Journal of Agricultural and Food Chemistry, shows that adding cow’s milk makes the lipid composition of infant formulas and breast milk more similar.


Selected lipids provide a comprehensive comparison

The following four lipids were selected for the fat similarity index because they have demonstrated health benefits and have been shown to be essential for normal growth and development of infants.


The milk fat globule membrane (MFGM), which surrounds fat globules in mammal milk, is rich in bioactive components, such as phospholipids *3. Some phospholipids such as sphingomyelin, which is needed for brain development, is present in breast milk fat and milk fat, but not in vegetable oil fats.

Short- and medium-chain fatty acids

Medium-chain fatty acid (MCFA) content is also a differentiating factor between milk fat and most vegetable fats. MCFAs are easily digested and absorbed by infants and oxidized to energy faster than long chain fatty acid. Early-life intake of MCFAs may also protect against obesity and metabolic disorder in adulthood. *4

Breast milk 90-150 mg/l
Milk fat 40-50 mg/l
Vegetable oil 0 mg/l

Cholesterol is essential for growth and development. Low dietary intake of cholesterol during infancy up-regulates endogenous cholesterol synthesis, resulting in higher blood cholesterol levels in adolescence and adulthood. *5

Sn-2 fatty acids (including OPO)

Milk-fat-based infant formulas also contain natural OPO *6, which enhances the absorption of nutrients, gut wellbeing, and healthy growth *7. In vegetable-oil-based formulas this level is very low.

Interested in more information?

Anu Turpeinen, PhD

Nutrition research managerFor more information on Valio’s solutions for infant nutrition, contact our Nutrition Research Manager Dr. Anu Turpeinen.

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The fat similarity index — evidence supporting the use of cow's milk fat in infant formula.

In this episode of Expert insights, Valio’s research specialist Anu Turpeinen explains the similarities between cow’s milk fat and breast milk — and why infant formula makers would benefit from using cow’s milk fat as the ingredient.

Watch the episode
What’s new in milk fat and infant nutrition?
What makes cow milk fat the optimal source of fat in infant formulas?
Valio webinar: Milk fat and vegetable fat in infant nutrition

* References:

  1. Al-Abdi et al 2017
  2. Hokkanen et al., in press
  3. Brink & Lönnerdal 2020
  4. van de Heijning et al 2017
  5. Parikh et al 2009, Hui et al 2019
  6. Fabritius et al 2020
  7. Havlicekova et al 2015