Whey & Casein: which is better digested?

Baby’s Only Organic® Premium Formulas, Baby’s Only Organic® Sensitive with DHA & ARA Formula, Baby's Only Cholov Yisroel and PediaSmart®Dairy are dairy-based and thus have a whey to casein ratio of 18:82, the same ratio found in cow’s milk.

Baby's Only Organic Gentle Dairy and Gentle with DHA & ARA formulas have a whey to casein ratio of 60:40.

Non-fat cow’s milk has been used for decades in formulas. These formulas have had a whey to casein ratio of 18:82 and have been clinically researched to document their safety and nutritional adequacy in supporting a child’s growth and development. These formulas are known as casein-predominant formulas.

Because of research documenting the unique components and benefits of human milk, the thinking was that the addition of whey to formula to achieve a whey to casein ratio of 60:40 would be beneficial.  The formula industry has introduced some formulas containing this 60:40 ratio and these formulas are referred to as whey-predominant formulas.

Both casein-predominant and whey-predominant formulas have been used for decades and are nutritious and healthy to support a child’s growth and development.

Little Miss Muffet's Curds & Whey

Casein and whey are the two major proteins found in cow’s milk. Approximately 82% of cow’s milk protein in casein and 18% is whey. The children’s nursery rhyme about Little Miss Muffet who sat on a tuffet eating her curds and whey helps to explain these two types of protein. Curds are the casein portion of cow’s milk protein and whey is the more liquid portion. So Little Miss Muffet was most likely eating cottage cheese! When milk is mixed with an acid such as vinegar, you get small curds and liquid whey resulting in cottage cheese. When we consume milk, the same thing happens during the digestion process in our stomach; that is, the casein forms small curds that take a bit longer to digest than the watery whey portion of the milk.

Casein & Whey Debate

There have been various debates about whether a dairy-based formula should be casein-predominant or whey-predominant. The reason for these debates is that human milk is commonly reported to have an whey to casein ratio of 60:40 versus the 18:82 ratio of cow’s milk. In fact, the whey to casein ratio in breast milk varies over time. According to a very well respected human milk researcher, “there is no ‘fixed’ ratio of whey to casein in human milk; it varies throughout lactation” and “the frequently cited ratio of 60:40 is an approximation.”1 Proteins are made up of molecules called amino acids. The types of amino acids found in human milk whey are different than those found in cow’s milk.2 Both types of formulas have been used for many years and are known to support the proper growth and development of children.

A formula made from cow’s milk will have a whey to casein ratio of 18:82 similar to that found in cow’s milk and is called a casein-predominant formula. Some manufacturers add cow’s milk whey to infant formula to bring the whey to casein ratio closer to breast milk in the belief that a 60:40 ratio is better for an infant and there are a few formula manufacturers who use only cow’s milk whey claiming “gentler” proteins and/or easier digestion. These formulas with added whey or only whey as the protein source are called whey-predominant formulas. Years of research on casein-predominant formulas and more recently on whey-predominant formulas have shown that both are nutritious and easily digested.

1 Lonnerdal B. Nutritional and physiologic significance of human milk proteins. American Journal of Clinical Nutrition. 2003;77:1537S-1543S.

2 Duggan C, Watkins JB, Walker WA. Nutrition in Pediatrics, 4th edition. Hamilton, Ontario, Canada: BC Decker, 2008, page 384

Baby's Only Organic® Dairy Formulas are Easily Digested

Standard dairy-based formulas such as Baby's Only Organic® Premium Baby’s Only Organic® Premium with DHA, Baby’s Only Organic® Cholov Yisroel, and Baby’s Only Sensitive with DHA formulas derive their protein from organic non-fat dried cow’s milk without added whey. So these formulas are considered casein-predominant formulas. Healthy children have no problem digesting the casein found in standard dairy-based, casein-predominant formulas.1,2,3,4 Pediatric nutrition experts have stated: “For a term healthy infant, there is no nutritional advantage of whey-predominant over casein-predominant formulas”1

Because every child is unique, a whey-predominant formula, such as Baby’s Only Organic® Gentle Formula and Baby’s Only Organic® Gentle  Formula with DHA, is often recommended because in some infants it produces softer stools.  Both whey-predominant and casein-predominant formulas provide appropriate and safe nutrition to support a child’s growth and development.


1 Wilson T and Temple NJ (editors). Beverages in Nutrition and Human Health. Totowa, New Jersey: Humana Press, 2004, page 238.    Billeaud, C et al. “Gastric emptying in infants with or without gastro-oesophageal reflux according to milk type,” European Journal of Clinical Nutrition. 1990 Aug; 44(8):577-583. 

2 Fomon SJ. Infant feeding in the 20th Century: Formula and Beikost. Journal of Nutrition.2001; 131: 409S-420S.

3 Duggan C, Watkins JB, Walker WA. Nutrition in Pediatrics, 4th edition. Hamilton, Ontario, Canada: BC Decker, 2008, page 757.

4 Martinez JA, Ballew MP. Infant Formulas. Pediatrics in Review. 2011; 32: 179-189.

5 Nielsen SS (editor). Food Analysis. New York, New York: Springer Science and Media, 2010, page 274.



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