A smaller number said they simply didn't like the taste or thought it would make them fat. Regular cow's milk now competes with goat's, rice, coconut, soy, nut and oats milks on supermarket shelves. Credit:Scott Barbour More women than men are avoiding milk and dairy foods that are rich in nutrients including calcium, iodine, and vitamins A, D and B12. "The scale of people restricting their diet without a medical reason is very concerning in terms of the public health implications, especially for women," said CSIRO's Bella Yantcheva, a behavioural scientist on the research team. "It means there is potential for nutritional deficiencies or imbalances, or the risk that an underlying health condition could be going untreated."

Most people need at least two to three serves of dairy, such as cheese and yoghurt, each day, according to the Australian Dietary Guidelines. One cup, or 250ml, of fresh milk constitutes one serve. Since Murray Goulburn's listing in 2015, shares in the MG Unit Trust have fallen from $1 to a record low of 84¢ each. Credit:Louie Douvis While consuming dairy can cut the risk of osteoporosis, colorectal cancer and type 2 diabetes, shoppers are increasingly seeking plant-based alternatives such as rice, nut and oat milks. Nutritionist Rosemary Stanton, who helped develop the national guidelines, said those on dairy-free diets, such as vegans, needed to ensure they get the nutrients in milk from other foods. Drinking milk reduces the risk of osteoporosis. Credit:Quentin Jones

"They're fine for adults but rice, oat and almond milks are not adequate substitutes for young children who also need the protein and riboflavin and a few other nutrients in mammalian milk." She said myths, such as the belief that calcium in milk isn't well absorbed by the body and that milk triggers mucus production, had contributed to the fall in consumption. "Some think it's not natural for humans to drink the milk of another mammal but for those who can happily tolerate lactose, milk is a perfectly OK food and no more unnatural than breeding cows and other animals and eating their flesh." She also said she was concerned people were self-diagnosing "symptoms" such as bloating as related to their diet, when there might not be a direct link. "The exact food varies with whatever is trendy at the time and the 'symptoms' also vary – often vague such as 'brain fog', or feeling unhappy or tired.

"These may have nothing to do with diet and more to do with some other aspect of life such as lack of sleep, overwork or unhappiness in a work or personal relationship." The CSIRO and the University of Adelaide researchers also found about a third of the respondents avoiding dairy foods were also avoiding wheat-based foods. They found about 10 times as many Australians than those diagnosed with coeliac disease were avoiding wheat-based foods. "The numbers show that cutting out significant, basic food groups isn't a fad but something far more serious," said Ms Yantcheva. "It's not just about missing out on the food type being avoided and risking your health, but also possibly overconsuming other foods to compensate as well."

CORRECTION: An earlier version of this story was amended to more accurately reflect the reasons women were avoiding milk in their diet. Latest consumer affairs news