There are good reasons why many people prefer soy milk to cow's milk. For example, the carbon footprint of soy milk is only a fraction of that of cow's milk. But the main question is which milk is healthier.
Cow's milk is the complete food for the growth and development of a calf. It contains all the essential amino acids as well as fats, carbohydrates, vitamins and minerals such as calcium, phosphate and vitamin B12.
The soya bean is complete nutrition for the growth and development of the soya plant. The needs of a plant are obviously different from those of a mammal, which is why soya milk contains less fat, carbohydrates, certain vitamins and calcium than cow's milk.
The protein content is about the same in both types of milk and all the essential amino acids of cow's milk are present in soya milk, albeit in smaller quantities. Soya milk, on the other hand, contains more fibre and twice as much folic acid as cow's milk.
However, the difference between cow's milk and soya milk is less clear when looking at industrially processed products. In industrial processing, the milk is heated to destroy bacteria and enzymes, which can be harmful to health and can shorten the shelf life of the product.
Soya milk from the supermarket is not usually made from ground soya beans, but from powdered soya protein isolate, which is enriched with water, oil and sugar to equalise the fat and carbohydrate content of cow's milk. It is also enriched with vitamins and calcium. After production, the difference between soya milk and cow's milk is therefore not in the amount of carbohydrates, proteins and fats, but in the type of these.
The carbohydrate content of cow's milk consists of lactose, the milk sugar, which requires the enzyme lactase for digestion. In mammals, including humans, the production of this enzyme decreases after weaning, so too much milk can cause flatulence and diarrhoea. Some people become lactose intolerant, for whom soya milk is an important alternative as it contains no lactose.
Soya milk and cow's milk both contain proteins, albeit with different benefits. Soya milk appears to have a heart-protective effect due to the secondary plant substances it contains. The proteins in cow's milk (casein and whey) promote muscle formation and weight loss.
Both types are available with different fat contents. Cow's milk contains mainly butterfat, which is rich in saturated fatty acids, while soya milk contains mainly polyunsaturated fatty acids, as vegetable fats are usually added. Even though it is recommended to pay attention to the reduction of saturated fatty acids and the diet, whole cow's milk does not seem to have a negative effect on the heart, probably due to the combination of fat, protein and mineral complexes.
Fresh cow's milk and fresh soya milk from the health food store are fundamentally different, but there is little difference in conventional milk from the supermarket. So if you opt for soya milk for environmentally friendly reasons, there is no health disadvantage.
Cover photo: Carl Baker
