Milk and other nutrient-rich dairy products such as yoghurt and cheese are one of the most affordable sources of nutrition. They provide us with energy, protein and carbohydrate; and with minerals including calcium, potassium, phosphorus; and vitamins A, D and B12, riboflavin, and niacin. While milk a valuable source of nutrients for young and old alike, it is very easily overconsumed. So, think of it as food in liquid form. The recommended intakes vary for different ages and stages of life, but for healthy, non-pregnant adults around 250–450ml of low-fat milk a day is suitable. For children, reduced fat dairy foods are recommended from two years of age.
Lactose, the sugar that occurs naturally in milk, is digested into glucose and galactose by the enzyme lactase found in the small bowel of all mammals at birth (apart from those born with lactase deficiency). A person without enough lactase has digestive problems when they consume foods and drinks that contain lactose. About a third of the world’s population continues to produce lactase throughout life. The rest don’t. However, there are many lactose-free milks on the market, so there’s no need to go without calcium-rich dairy foods. Some people who are lactose intolerant find they can enjoy yoghurt because the micro-organisms added to milk to make yoghurt breakdown lactose - in other words, the “bugs” help do the job of lactose digestion for you. People with lactose intolerance can eat cheese because it is made from milk solids (curd); the lactose-rich whey has been drained off during the early stages of processing.
Calcium is essentially why dairy foods are recommended throughout childhood and beyond as it’s the key to strong healthy bones. But dairy milk is not for everyone. If you are lactose intolerant, have a milk allergy or eat only plant foods, non-dairy options that will boost your calcium intake include almonds, brazil nuts, sesame seeds, dried figs, dried apricots, soybeans, dark leafy greens, dried legumes, Asian greens such as bok choy, calcium-enriched tofu and calcium-fortified breakfast cereals.
Source: AUSNUT2013