Cows` milk and formula milk - what makes them different?

Even after a baby’s first birthday, cows’ milk may not be the best choice for the main drink, especially for children who do not consume a wide range of foods. The nutrient content of follow-on and growing up milks is much greater than that found in the same quantity of cows’ milk³, and may provide a valuable addition to the diet. This article provides evidence-based information for Healthcare Professionals to use in situations when cows’ milk use is discussed, such as:

• Why cows’ milk is unsuitable as the main drink for infants
• When a parent wants to introduce cows’ milk as their child’s main drink
• When alternative milks may improve the child’s nutritional status
• When children are consuming too much milk

Breastmilk
Breastmilk provides the optimum method of feeding, meeting all the nutritional, health and growth needs of a normal term infant. It contains over 300 components including growth factors, enzymes, antimicrobial agents, antibodies and many substances that are not yet understood and cannot be replicated in infant formulas⁴.

The composition and quantity of breastmilk changes to meet the growing infant’s health and nutritional needs⁵. Breastfeeding can – and should – be continued for as long as the mother and child want, establishing a bonding that can probably never be replicated in other feeding methods. If a mother continues breastfeeding beyond 6 months, however, its nutritional value has peaked and will decline by up to 30% by the time an infant is 1 year of age⁶. Therefore it is important that a wide range of solid foods are introduced during the second 6 months of life.

The hormones and growth factors in breastmilk are likely to have many long-term health benefits. Breastfed infants grow at a different rate compared with formula-fed infants, and may be less likely to become obese in later life⁷. Other suggested long-term health benefits of breastfeeding include a lower incidence of gastro-intestinal upsets, otitis media, cardiovascular disease, diabetes⁸ and hypertension⁹ in breastfed, compared with formula-fed, infants¹⁰. Ongoing developments with formula milk composition seek to provide ingredients that offer significant health benefits (such as the addition of prebiotics (oligosaccharides).

Infant formula milks
Several nutrients known to improve infant growth and development are routinely included in standard formula milks¹¹. Often, the nutrient levels are much higher in formula milks than in breastmilk, but direct comparisons are not possible because the efficient absorbency of breastmilk means that optimum nutrient levels are provided until at least the first 6 months. Two broad types of formula milk are suitable for infants under 6 months of age who are not exclusively breastfed:

• First milks: whey-dominant formulae are suitable from birth. They are easily digested and are ideal for demand feeding.

• Second milks: these casein-dominant formulae are also suitable from birth, but it can be useful to suggest these milks for babies who are being bottle-fed on demand, but who are not satisfied with whey based formula. Casein takes longer to digest and therefore second milks may help those who wish to re-establish a more regular feeding pattern for their baby. Casein-dominant formulae are also worth suggesting if parents are keen to start weaning a hungry baby before six months of age, as these milks may help to delay early weaning.

Milks for older babies
First and second milks are both suitable for use throughout the first year of life. However, the following modified milks offer good solutions to providing the nutrients required by children over six months of age, as part of a mixed diet:

• Follow-on milks: contain quantities of protein, sodium, iron and vitamin D that meet the needs of an older baby who is on a weaning diet and who requires less milk volume per day. Follow-on formulae are particularly useful in babies who do not consume adequate quantities of first milks or weaning foods. In older infants who continue breastfeeding, it may be useful to recommend mixing follow-on milk with weaning foods (e.g. cereals, custards), to help increase the nutritional quality of the diet. Health Visitors may also recommend multi-vitamins for older breastfed babies.
• Growing-up milks: although cows’ milk can be given after 12 months, growing-up milks are nutritionally superior alternatives. They contain much higher concentrations of vitamin C, vitamin D and iron than cows’ milk, as well as other essential nutrients to support the toddler diet. Growing-up milks, such as Cow & Gate, are also fortified with prebiotic oligosaccharides.

The drawbacks of unmodified cows’ milk
Breastmilk and formula milk provide a broader range of nutrients and micronutrients, and are more easily digested by the immature infant gut, compared with unmodified cows’ milk¹¹.

Protein burden
Mammalian milks provide amino acids and essential amino acids at levels appropriate for each species’ growth and development. Consequently, cows’ milk is designed for calves, not baby humans!

• Cows’ milk contains approximately 80% casein and 20% whey protein
• Breastmilk varies from 80–60% whey dominance; whey-dominant formulas contain ~ 60% whey protein¹²
• Cows’ milk contains a higher overall proportion of protein compared with breast and formula milks¹¹
• Cows’ milk also has high levels of sodium, potassium and calcium. Coupled with the protein burden, this can place an undue strain on the immature digestive and renal systems, increasing the risk of severe dehydration (especially in babies with gastrointestinal illness or low fluid intake)¹³
• There is controversy about the role that a high-protein diet during the early years of life has on later health: it may¹⁴ or may not¹⁵ increase the risk of obesity. Early feeding patterns are certainly associated with the development of several chronic diseases^9,16. Breastfeeding for at least the first 6 months, followed by age-appropriate formula milks for the first 2 years, helps to ensure that protein intake remains within safe dietary limits (8–12%)¹⁷.

Fat differences
The fats in breastmilk and infant formula provide about half of a baby’s energy requirements for the first 6 months of life¹⁸, and also supply vitamins A, D, E and K, essential fatty acids, and long-chain polyunsaturated fatty acids¹⁹. Fats in breastmilk and formula milks are easier to digest compared with fats in cows’ milk, therefore micronutrients are better absorbed from these sources¹¹.

The iron issue
The iron in cows’ milk is also poorly absorbed by humans and is available in very low quantities (typically 0.3 mg/l), compared with standard infant formula (7 mg/l) or follow-on milks (>10 mg/l). Although breastmilk has a low iron content (~0.08 mg/l), it is efficiently absorbed and a baby’s iron stores generally remain sufficient for 6 months’ exclusive breastfeeding¹¹. Cows’ milk has several adverse effects on iron levels^13,20. More specifically, its high calcium and casein levels inhibit non-haem iron absorption²⁰. Babies who consume cows` milk as their main drink at 6 months of age are more likely to be anaemic by 12 months, and have low serum ferritin levels at 8 and 12 months²⁰. Regular cows’ milk consumption may cause gastrointestinal bleeding in the first year of life: occult intestinal blood loss affects up to 40% of normal infants fed cows’ milk^13,21.

Dairy foods and weaning
Confusion arises at weaning because several dairy products are permitted for use in the weaning diet, even in first-stage foods: Department of Health (DH) guidance states that cows’ milk can be consumed in small quantities (e.g. to mix with cereals or in sauces)¹. This may seem inconsistent to a parent and needs careful explanation. Certainly, the number of parents who use infant formula and follow-on milks for babies over 6 months old is increasing^2,22. However research shows that some parents and informal influencers still view introducing unmodified cows’ milk as an important and desirable milestone². But if parents fully understand that cows` milk is not designed for infants and toddlers, they are less likely to rush its introduction. It is interesting, however, that the recent commentary on infant feeding practices in the UK failed to discuss current unmodified cows’ milk use²².

Other nutritional limitations of cows’ milk
Concentrations of essential fatty acids, zinc, vitamin C, and niacin are low, and saturated fat levels are high, compared with breastmilk, standard infant formula or follow-on milk. Cows’ milk is also high in phosphates, which may inhibit calcium absorption. The antioxidant taurine is present in breastmilk and infant formulae, but not cows’ milk. Unlike breastmilk and some infant formula, cows’ milk does not contain long-chain polyunsaturated fatty acids and nucleotides, which are important for brain and neuronal development²³. Cows` milk also contains low levels of iron and vitamin D.

Prebiotics
Breastmilk and some formula milks (including Cow & Gate`s) contain prebiotic oligosaccharides. Prebiotic oligosaccharides have been shown to support babies` healthy digestion ^{24, 25}. Cows` milk does not contain prebiotic oligosaccharides.

Introduce cows’ milk safely, in moderation
When parents want to introduce cows’ milk as the main drink for a baby over 12 months old, the Department of Health recommends:

• Full-fat cows’ milk, between 1 and 2 years of age
• Semi-skimmed milk, after 2 years
• Skimmed milk, only suitable from 5 years²⁶

Children who are consume excessive amounts of cows` milk may face an increased risk of cardiovascular events in adulthood, although evidence to support this is somewhat limited²⁷. At 12 months, an infant should consume no more than 1 pint (600ml) of unmodified cows’ milk, infant formula or a follow-on milk per day^18,26. A litre (1000ml) of cows’ milk contains two-thirds of a 12-month-old baby’s energy requirements: children who consume excessive quantities have little room, or appetite, for other foods and are also at risk of becoming overweight or obese²⁸. Nutritional deficiencies, especially iron deficiency anaemia, are also more likely in those who consume excessive amounts of milk^28,29. To reduce the volume of milk consumed, parents can:

• Offer water instead of milk
• Restrict milk consumption to after meals
• Feed milk from a cup, not a bottle
• Reduce the amount of milk put into the cup (or the size of the cup used)

Conclusions
It is important that Healthcare Professionals communicate the drawbacks of early cows’ milk use to parents. Cows’ milk is an unsuitable main drink for infants under 1 year of age because its nutritional value is based on the needs of calves and not those of human babies and it is difficult for the immature renal and digestive systems to process. Although small quantities of cows’ milk can be used as part of weaning meals – and it can be given as the main drink after 1 year of age – breastmilk, infant formula, follow-on and growing-up milks provide a broader range of nutrients and the fortified milks in particular may be useful for older children who are not eating a wide variety of foods.


Click here for information on Cow & Gate Growing Up Milk for toddlers from 1 - 2 years.Click here for Cow & Gate`s Iron Calculator to help parents check if their toddler is getting enough iron

References

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