Nut milks: People are entitled to their personal preferences but it is important to understand the nutritional value and health outcomes based on the scientific evidence.
The range and sales of plant beverages on the market is increasing, with soya, almond, cashew, oat, rice, coconut and others now widely available in New Zealand.
Marketing these products as “milk” raises the hackles of dairy farmers and processors, and prompting the US Food and Drug Administration to think about enforcing the rules on product descriptions.
Plant beverages are not milk, which is a well defined food product. Dr David Everett, a Riddet Institute Fellow at AgResearch, thinks the horse has probably bolted on that one.
Processors argue that consumers know plant-based beverages are not ruminant (cows, sheep, goats) milk, so see little reason to change.
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But Everett says it can deceive the consumer and could result in well-meaning parents giving plant-based beverages to babies and infants, who need the complex lipids present in their mothers’ or ruminant milk for proper development, cognitive as well as physical.
Of course, mother’s milk is best.
This article looks only at the nutritional differences between ruminant milk and plant beverages, not the reasons why people drink them, or the environmental costs associated with each product.
“People are entitled to their personal preferences for milk or plant-based emulsified beverages, but it is important to assess the nutritional value and health outcomes based on scientific evidence,” says Everett.
Milk is highly digestible, and has the right proportions of the nine essential amino acids we need to consume every day because our body cannot make them.
Plant beverages have different amino acid and nutrient make-ups. None, except soya, contains all nine essential amino acids. They have a simpler structure but are often less digestible than milk.
A characteristic of milk is lactose, which helps the body absorb the rich supply of calcium in milk. There is no lactose in plant beverages, which have little or no calcium naturally, but do have it added.
However, it may not be as readily absorbed as the calcium in milk. Plant beverages are highly fortified and are more processed than milk. They are relatively low in calories and all have some advantages, such as almond milk, which has Vitamin E and antioxidants.
Between 70 per cent and 80 per cent of people of Asian or African origin do not have the genetic mutation that enables carriers to digest lactose into adulthood. This mutation spread through the human population thousands of years ago.
If lactose-intolerant people drink ruminant milk after weaning, the lactose can pass through the stomach into the intestine where it draws out moisture and causes diarrhoea and other symptoms such as bloating and stomach cramps.
This is purely a physical effect that is symptomatic at high concentrations. Yoghurt contains a relatively small amount of lactose compared to milk, and hard cheeses such as cheddar have none.
Lactose intolerance is not the same thing as a dairy allergy. This is where people react to some proteins in milk and suffer an inflammatory reaction.
Plant-based beverages are lower in saturated fats than milk. “However,” says Everett, “consumption of the saturated fats naturally present in milk does not necessarily raise blood cholesterol.
“There is even some evidence that increasing milk consumption decreases cardiovascular disease and that cheese has no effect on cholesterol in the bloodstream.”
Dr David Everett is Riddet Institute Fellow and Science Impact Leader at AgResearch. Glenda Lewis is a science communicator.