Sheep milk more easily digested than cow milk

Sheep milk’s protein is more readily digested and its fats are more readily converted into energy compared to cow milk, a New Zealand study has shown.

The milk’s unique composition could make it a good option for the very young and the elderly, sports nutrition, and people who are looking for alternatives to cow’s milk, researchers say.

Anecdotally, evidence from consumers already suggests that sheep milk may be better tolerated than cow milk by some people.

This is believed to be the first human study in the world to investigate how differences in the composition of New Zealand sheep milk affect ease of digestion, digestive comfort, and the body’s ability to make use of milk protein.

Scientists from the University of Auckland-based Liggins Institute and the Crown Research Institute AgResearch ran the clinical trial with support from sheep milk producers Spring Sheep Milk Co. and Blue River Dairy LP.

The participants, 30 women who normally avoided drinking dairy, consumed 650 mL of either cow milk or sheep milk on two separate occasions. Afterwards, the women reported on their digestive comfort, appetite and liking, and provided breath and blood samples. During the trial neither the women nor the researchers knew who was drinking what at the time.  

Sheep milk has more nutrients per glass: more protein, fat, vitamins and minerals. For example, it has almost twice the level of calcium and zinc, compared to cow milk.

Dr Amber Milan Liggins Institute, AgResearch

Study co-lead Dr Amber Milan, a research fellow at the Liggins Institute and researcher for AgResearch, says, “We already knew that sheep milk is different from cow milk. It has more nutrients per glass: more protein, fat, vitamins and minerals. For example, sheep milk has almost twice the level of calcium and zinc, compared to cow milk.

“What our trial has shown is that New Zealand sheep milk is not just compositionally different to cows milk, but has inherent properties which means we digest it differently,” says Dr Milan.

“We have, for the first time, confirmed that the protein in sheep milk is more readily digested compared to cow milk. Sheep milk delivered more of the branched-chain amino acids (BCAAs) leucine, valine and isoleucine than cow milk. Amino acids are building blocks for protein, and these kinds are important for forming muscle protein.

The higher total fat levels do not produce a higher spike in blood triglycerides, probably due to the different types of fat in sheep milk. Sheep milk delivered more of some so-called ‘good fats’ (medium-chain fatty acids and conjugated linoleic acid, or CLA) than cow milk.

Dr Amber Milan

Spring Sheep’s Food Technology Research & Development Manager Natalie Macbeth says “The result of the clinical trial is good news for consumers who struggle with the digestion of cow’s milk. It’s great to be able to provide them with solid evidence that further supports the benefits of sheep milk.”

New Zealand now has more than 20,000 sheep for milking through 16 different producers. Significant new investment is going into milk processing and supply to overseas markets, which currently include China, Taiwan, Malaysia and Vietnam.

While sheep milk is traditionally used to make cheese and yoghurt, New Zealand businesses are leading the way in developing high value nutritional products including sheep milk infant and toddler formula, specialist nutritional formulations and drinks.

The researchers presented their findings at the Food Structures, Digestion and Health International Conference in Rotorua in October and are submitting their findings for publication in a scientific journal next year.  

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