Skip to Content

What animals breast milk is closest to humans?

When it comes to breast milk, humans are unique in many ways. Unlike other mammals, human breast milk contains the perfect balance of fat, protein, and carbohydrates to fuel a baby’s growth and development. It also contains important antibodies, enzymes, and hormones that protect infants from illness and disease. However, among mammals, there are some whose breast milk closely resembles that of humans in nutrient content and health benefits. Understanding what animal milk is compositionally similar to human milk can provide insights into the optimal nutrition for infants and young animals alike. In this article, we will explore and compare the nutrient profiles of human breast milk and that of other mammals to determine which comes closest to matching the gold standard of human milk.

Macronutrient Composition

The three main macronutrients found in breast milk are fat, protein and carbohydrates. Let’s look at how these compare across species:

Fat Content

Human breast milk contains approximately 4.4g of fat per 100ml. This constitutes nearly 50% of the energy content of breast milk to help fuel a rapidly growing infant brain. The high fat content also aids in the absorption of fat-soluble vitamins. The fatty acid composition is specific to humans, with high amounts of brain-boosting omega-3 and omega-6 fatty acids like DHA and ARA.

In comparison, the breast milk of the great apes – gorillas, chimpanzees, orangutans – contains 2.5-4% fat. This more dilute milk matches their slower infant growth rate compared to humans. Cow’s milk, on the other hand, packs a higher fat punch with close to 4.8g per 100ml. The fat composition also differs, with over 30 types of fatty acids in human milk versus only 13 in cow’s milk. Sheep’s milk tops the charts at 7.4g of fat per 100ml – nearly double that of humans! However, it lacks the ideal omega fatty acid profile.

Overall for fat content, cow’s milk comes closest to human milk, but lacks theFatty Acid diversity.

Protein Content

Human milk contains approximately 1.3g of protein per 100ml, with whey and casein as the major proteins. This nourishes lean muscle mass growth in the rapidly developing infant. In comparison, sheep’s milk also provides 1.3g of protein per 100ml, with a higher ratio of whey protein that may be more easily digested. Cow’s milk, on the other hand, contains a higher protein content of 3.5g per 100ml, which would be excessive for human infants. The protein content of gorilla, chimpanzee and orangutan milk ranges from 2.5-3.5g per 100ml – also too high for an exclusively milk-fed human baby.

Therefore, sheep’s milk aligns closest with human milk in terms of protein content and quality. The balance of amino acids in sheep’s milk gives it a slight advantage over cow’s milk.

Carbohydrate Content

The primary carbohydrate in milk is the simple sugar – lactose. Human milk contains approximately 7.2g of lactose per 100ml, which provides fast energy for the rapidly growing infant brain. Milk from other mammals contains similar amounts – 6-7.5g/100ml for cows, sheep and goats. However, the types of carbohydrates differ. Human milk contains unique complex oligosaccharides that act as prebiotics to support the infant gut microbiome and strengthen immunity. This gives human milk the advantage when it comes to ideal carbohydrate composition.

Table 1: Macronutrient Comparison per 100ml of Milk

Species Fat (g) Protein (g) Carbs (g)
Human 4.4 1.3 7.2
Cow 4.8 3.5 4.8
Sheep 7.4 1.3 4.8
Goat 4.1 3.6 4.5


In addition to macronutrients, breast milk contains vitamins, minerals and a plethora of bioactive components that support optimal health and development. Here is how the micronutrient profile of human milk compares to other species:


Human milk is rich in B vitamins, Vitamin A, C and D to meet the high metabolic demands of a rapidly developing infant. Ruminants like cows, goats and sheep have anywhere from 2-10 times the vitamin content of human milk. For example, 100ml of cow’s milk contains 1500 IU of Vitamin A versus 500IU in human milk. While vitamin-dense, excessive amounts can be toxic during infancy. Human milk contains optimal vitamin levels tailored for human infants.


The primary minerals in human milk include calcium, phosphorus and magnesium for bone growth along with iron, zinc and selenium for metabolism and immunity. Cow’s milk contains almost double the amount of many minerals compared to human milk. The excess sodium and potassium in cow’s milk makes it unsuitable as an exclusive food source for human infants. Goat’s milk provides the closest mineral match to human milk but still exceeds recommended intake for some minerals like iron.


Human milk contains a complex array of bioactive components like antibodies, enzymes, hormones, growth factors and prebiotics. These work synergistically to prime the infant’s immune system, digestive system and overall development. No other species’ milk matches the diversity and functional benefits of these protective bioactives in human milk. Cow’s milk, for example, contains only trace amounts of these important immunoglobulins and growth factors.

Table 2: Vitamin Content per 100 ml Milk

Vitamin Human Cow Goat Sheep
Vitamin A (IU) 500 1500 185 95
Vitamin B1 (mg) 0.05 0.44 0.06 0.10
Vitamin B2 (mg) 0.14 0.17 0.17 0.36
Vitamin B3 (mg) 0.55 0.08 0.26 0.33
Vitamin B6 (mg) 0.04 0.05 0.06 0.10
Vitamin B12 (mcg) 0.05 0.44 0.06 0.11
Vitamin C (mg) 55 1 4 8
Vitamin D (IU) 81 44 1 1


Among the milks of other mammals, there is no perfect replacement for human breast milk when it comes to adequately nourishing a human infant. The macronutrient ratios, micronutrient contents, and diverse bioactive factors in human milk are uniquely suited to support optimal growth, brain development, digestion, immunity and metabolism in a human baby.

However, when examining the compositional data, sheep’s milk appears to share the closest similarities with human milk. The protein and carbohydrate content of sheep’s milk nearly matches the ideal ratios found in human milk for infant growth requirements. The lower fat content is also closer to human milk than the high-fat milk of seals, cows and other mammals. Goat’s milk aligns with the vitamin and mineral profile of human milk better than cow or sheep milk, but the higher protein and minerals still exceed requirements.

Ultimately, the extent to which any animal milk can mimic the nutritional completeness of human breast milk is limited. For infant nutrition and providing the diverse benefits of bioactive components, human milk stands in a category of its own. However, for older infants and children, sheep and goat milk may provide the next best alternative from a compositional standpoint. Understanding these key nutritional differences helps inform the best feeding practices for infants across mammalian species.