In the year 1974, the UK population consumed 140 litres of milk per capita. By 2020, that figure had halved.
Today, just under 90% of people in the UK use cow milk. So how come we’re now consuming only 70 litres of milk per capita, per year?
We all know the answer, of course. Many people are opting for plant-based milk products. Almost one third (32%) of the UK population is using plant-based milk – commonly made from oats, almonds, soy, or rice – as an alternative to dairy milk.
Is plant-based milk healthier than dairy milk? Is it better for the environment? Does it taste as nice? Should we all give it a go?
Milk is the first food of infant mammals, secreted from a mother’s mammary glands. In most land mammals, this nutritious liquid comprises between 80% and 90% water. The remaining 10% to 20% is made up of fat, protein, carbohydrate, and minerals.
The carbohydrate content of milk is lactose, a disaccharide that’s broken down into its component simple sugars (glucose and galactose) by a digestive enzyme called lactase. These simple sugars are absorbed into the bloodstream through the walls of the small intestine and converted to energy.
Lactose digestion is the sole purpose of lactase. During the suckling period, an infant mammal produces a high level of this enzyme. Beyond infancy, milk is no longer part of the animal’s diet, and lactase production ceases.
Absence of the lactase enzyme means that when an adult mammal consumes milk, the lactose can’t be absorbed through the walls of the small intestine. Instead, the disaccharide passes into the colon, where it’s metabolised by bacteria. The fermentation of the sugar produces gas, which can cause a multitude of digestive disorders.
Approximately 10,000 years ago, humans began to domesticate animals – a cultural change that triggered a genetic mutation in our species.
Livestock presented a new source of nutrition: milk. Humans began to feed on the milk of other mammals, beyond infancy and into adulthood. The capacity to digest milk became an evolutionary advantage. Natural selection kicked in, favouring lactase persistence.
Lactase persistence (a phenotype shared by a third of the human population) is a uniquely human phenomenon.
Even people with the lactase-nonpersistent phenotype can tolerate about 11g of lactose daily – if the dairy products are consumed with meals, and intake is distributed over several hours.
But there are a couple of ways for people with lactose intolerance to enjoy plenty of dairy milk without suffering gastric complaints:
Animal milk is a rich source of calcium, a mineral that plays a role in bone formation, vascular contraction and dilation, nerve transmission, hormone secretion, blood clotting, and muscle functions. Besides milk, calcium is found in tinned salmon and sardines, which contain soft, edible bones, and in green leafy vegetables such as kale, watercress, and collard greens. For adults, the NHS recommends a daily calcium intake of 700mg.
So, how much calcium do you get from dairy milk?
How do these animal milks compare to some of the most popular plant-based milks?
Cattle, sheep, goats, buffalo, and camels are ruminants, and they emit methane gas as a by-product of organic decomposition by microorganisms in their digestive systems. Methane has a net global warming potential (GWP) 30 times that of carbon dioxide over a period of 100 years. Since the beginning of the Industrial Revolution, the concentration of atmospheric methane has more than doubled.
Cattle are the main source of milk for humans. At present there are more than 264 million dairy cows worldwide, all emitting methane gas.
About 38% of the world’s land surface is used for agriculture, and two thirds of this land is grazing pasture for livestock. The remaining third is cropland, and approximately one third of this cropland is used to grow feed for livestock. Deforestation means reduced CO2 absorption through photosynthesis and a consequent rise in atmospheric carbon dioxide levels.
Deforestation is also a major threat to biodiversity and the world’s ecosystems.
Plant-based milk is a beverage that resembles animal milk in appearance, consistency, and mouthfeel (texture). It’s made through numerous processes, including the soaking, grinding, heating, and filtering of plant material, which constitutes around 2% of the final product. Besides a water base, plant milk includes additives such as: polysaccharides for emulsifying and homogenising; vitamins and calcium; artificial colour to emulate animal milk; and artificial flavouring to emulate characteristics of the featured plant.
There’s a wide variety of non-dairy milks available, including:
Not all plant-based milks are environmentally sustainable.
Rice milk, in particular, is associated with methane emissions resulting from the flooding of rice crops. Water on the ground creates a barrier to atmospheric oxygen, providing an ideal environment for bacteria to ferment organic material. Rice milk has the greatest environmental impact in the context of GHG emissions, followed by soy milk.
Nut-based milks have a low impact on greenhouse gas emissions, as the nuts are sourced from leafy trees that sequester carbon dioxide.
Almond milk has the greatest water footprint, and in second place is rice milk. Oat milk represents the greatest land use, followed by soy milk.
However, all these plant-based milks are way behind cow milk in terms of GHG emissions, water use, and land use.
From an environmental point of view, maybe we should.
If you love the taste of milk in a cup of tea or coffee made with pure water, nothing can replace it.