A 'worrying' number of people in the UK suffer from insufficient vitamin D yet it is almost impossible to boost levels with diet, said Dr Richard Keen, director of the Metabolic Bone Disease Unit at the Royal National Orthopaedic Hospital in Stanmore, north London.

Consultant rheumatologist Dr Keen was speaking at the Women's Health in Primary Care conference in London this week, organised by the journal MIMS Women's Health.

He said around 60% of people aged between 19-24 had insufficient vitamin D levels, with the number falling slightly in middle age before rising to 70% of 65-85 year olds.

'It is a big problem across the spectrum,' said Dr Keen.

To raise vitamin D levels significantly, a patient would have to eat 2.5 portions of tuna a day or drink 50 pints of milk or eat nine large eggs, said Dr Keen.

Vitamin D deficiency is known to cause rickets and a variety of bone-thinning diseases. For osteoporosis drugs to work effectively, users require adequate levels of vitamin D and calcium.

Dr Keen also warned that some laboratories miss ‘masses' of patients with insufficient levels of vitamin D, by only flagging up those with full blown deficiency.

Any concentration lower than 75nm/ml could be considered insufficient, he said.

• More information on MIMS conferences