We have long been told that milk is essential for strong and healthy bones. Now new research has confirmed that children who drink milk are less likely to develop osteoporosis later in life.

Osteoporosis is a condition in which there is a thinning of the bones, causing them to fracture (break) more easily.

Researchers looked at over 12,500 non-pregnant women aged 20-34. The participants underwent a comprehensive assessment of diet, lifestyle and body measurements. For those who had conceived at some stage – around 3,000 of the women – the assessment covered before and during pregnancy. A number of their children were also assessed to determine what influences a child’s bone growth.

The study found that patterns of bone growth in the first few years of life can strongly influence the onset of osteoporosis decades later.

According to the researchers, the amount of bone in the skeleton, known as bone mass, peaks between the ages of 20 and 30. Babies and children who are underweight and undernourished are likely to have a lower bone mass in early adulthood than normal, which would make them more vulnerable to osteoporosis in later life.

"We wanted to find out what factors determine whether a child with lower bone mass at birth catches up compared with other children in later life. We think that diet during childhood may make a difference. In our study, catch up in bone mass compared with other children in the group was associated with drinking more milk in childhood”, explained Dr Nick Harvey of the University of Southampton.

He said that the findings held true even when genetic factors were taken into account. This suggests that both the genetic make-up of the child and factors such as diet are important for bone growth.

After peak bone mass is reached in early adulthood, bone mass declines with age, particularly after the menopause in women. Research has shown that the higher the peak bone mass gained, the lower the risk of osteoporosis in later life.

"Thus factors which influence bone growth from conception to peak are likely to be crucial in reducing the risk of fractures in older age," Dr Harvey said.

The findings highlight the importance of both genetic and environmental factors in determining bone growth. However the research also shows that the biological processes involved with bone growth start before the child is even born.

“It is therefore important to consider what can be done to improve bone health throughout the life time of the individual. Since this starts when the baby is conceived, parental health and lifestyle at conception and during pregnancy are likely to be vital factors," Dr Harvey added.

He presented the findings of the research at the 35th European Symposium on Calcified Tissues in Barcelona.