There's a belief that the market for milks for digestive wellness is dominated by plant milks. In the US, this is no longer true. Lactose-free cows' milk now leads the category.

The misconceptions about the market size and growth rate of plant milks originate from consultants and media. But when you scratch at the surface of this myth, it's clear that plant milks have peaked as a niche business and the category has stopped growing – and, in 2023, even started to decline.

We can see this clearly with a heatmap, a data visualisation often used in the worlds of finance and engineering. This New Nutrition Business heatmap shows the data for 2023 for the US market for milks for digestive wellness – meaning plant milks, lactose-free cows' milk and goat milk.

- The size of the square shows an individual product type's share of the market. The bigger the square, the bigger the share. In this case, it's showing millions of gallons sold.

- The colour tells you whether sales are growing (green) or falling (red).

- The figure shows percentage growth (or decline).

What the heatmap reveals is that consumption of lactose-free cows' milk is bigger than that of every type of plant milk, selling four times the volume of oat milk. The gap will only widen from here.

Plant milks are bought by consumers who experience digestive difficulties from dairy milk but still want a milk-like beverage. As the chart shows, consumers increasingly favour lactose-free cows' milk over plant milks. It has the biggest share of the category and is adding more volume every year than any plant milk.

Dairy's advantage is that is seen by most consumers as "real food". Consumer interest in "real foods" has been steadily growing for some time and has played a big role in how lactose-free is now outpacing plant milks. For many people, lactose-free dairy milk is the butter – unprocessed, natural and tasty – and plant milks are the margarine, with a long ingredient list, over-processed and often not tasty enough.

In 2023 US plant milks accounted for a 15.5% value share and a 9.8% volume share of the total US liquid milk market, according to supermarket sales data supplied by Circana. Also in 2023, plant milk sales fell by 6.5%, measured by volume, following a 6.8% decline in 2022.

Plant milks are an almond and oat business, as the map shows, but almond has entered a decline from which there is no way back.

The US plant-based milk market may be the world's biggest. But as the heatmap reveals, it's a big niche, and one that is past its peak.