Demand for blood to meet the medical needs of a growing and greying population has shot up over the last five years.

Latest Health Sciences Authority (HSA) data shows that 111,633 units of blood were used last year, up 17 per cent from 95,100 in 2011.

However, the volume of blood collected has grown at a slower pace of about 10 per cent - from 104,895 units in 2011 to 115,976 units last year.

This is partly because the ageing population poses a double-edged challenge to the national blood situation, said the Singapore Red Cross (SRC) and Health Minister Gan Kim Yong yesterday.

Said Mr Gan: "On the one hand, an ageing population means blood demands will increase. The elderly are more likely to develop age-related medical diseases like heart disease and stroke. The demand for blood to support more medical and surgical procedures may also continue to rise.

"On the other hand, our blood donor pool may shrink, as regular donors can no longer give blood if ill health strikes when they get older."

He was speaking at an award ceremony to recognise the efforts of regular blood donors at the Singapore Sports Hub yesterday, which was also World Blood Donor Day.

He presented the Medal For Life award to 13 donors; each made more than 200 blood donations.

In the last five years, an average of about 600 regular donors stopped donating each year due to age-related illnesses. Yet every day, many patients undergo major operations and they may each need two to four bags of blood.

Accident victims may need more than six bags of blood. Others, such as thalassaemia patients, need regular blood transfusions.

Said SRC chief executive Benjamin William: "Beyond personal and national emergencies, there are people who need blood every few weeks throughout their lives in order to live."

Over the years, HSA and SRC have opened three satellite blood banks and organised community drives to make blood donation convenient and accessible.

However, only 73,587 people - or about 2 per cent of the resident population - stepped forward to donate blood last year. The donations went to 30,000 patients.

Mr Gan noted that 60 per cent of blood donors last year gave blood only once.

That is why SRC has been getting creative in generating awareness about donating blood.

Last year, it launched the "Missing Type" campaign, which saw more than 60 participating organisations ranging from schools to government agencies and retail brands remove the letters A, B and O (which represents the different blood groups) from their websites and social media profiles.

The campaign sparked a 16 per cent jump in blood donations that month.

Mrs Lu T. Aida, who made her 100th donation last year, yesterday received the Diamond Award.

The 70-year-old, whose blood is type A, started donating in 1983, when her father-in-law had liver cancer. He needed O-type blood and she felt helpless because she could not donate.

So she made a pledge to help others if he recovered.

And even though he died shortly after, she continued donating over the years.

"It's a joy to be able to help others," she said.