One perk of getting old in Japan is a gift of a silver cup from the prime minister in the year you celebrate your 100th birthday. But from this year, new centenarians will be sipping sake from cheaper vessels.

The rising cost of supporting the aging population — almost 32,000 people were eligible to receive the gift this year, up 4.5 percent from last year — has prompted Prime Minister Shinzo Abe’s government to present cups made of silver plate rather than sterling silver. The move halves the price to ¥3,812 per cup, public broadcaster NHK said, reducing total spending on the gifts by about 40 percent to ¥150 million.

The cost-cutting follows a move to make the cups smaller in 2009, and highlights the struggle the government faces to cap spending in a debt-ridden country where more than a quarter of Japan’s 127 million people are older than 65. The proportion will rise to 40 percent by 2060, the government projects — a problem compounded by a faltering birthrate.

This predicament is perhaps seen most clearly by the swelling of centenarians from 153 in 1963 to a record of more than 65,000 this year. The government distributes the sake cups every September to honor the elderly.

The demographic shift puts pressure on the country’s social welfare programs in areas such as medical care and pensions, according to Hiromichi Shirakawa, chief economist at Credit Suisse Securities Japan.

“There’s no doubt that medical expenses will keep increasing as the population grays,” Shirakawa said. “Providing pensions to the elderly will also become an issue. The government will have to raise the age at which people can receive pensions to ease the problem.”

The Ministry of Health, Labor and Welfare is seeking ¥31 trillion for its budget in the fiscal year starting April, up 2.7 percent from this year. About ¥29 trillion is slated for health care and pensions.

Japan’s oldest person is 116-year-old Nabi Tajima, from Kagoshima Prefecture.

According to a profile published by the health ministry, the secret to her longevity is eating three meals day.

Another profiled centenarian, Junichiro Misawa from Hokkaido, said his good health and long life is due to “having a few evening drinks a week and not being picky about food.”

The world’s oldest person, however, is not Japanese.

Born on Nov. 29, 1899, Emma Martina Luigia Morano, 116, of Vercelli, Italy, was confirmed by Guinness World Records in May as the oldest living person on Earth. The oldest person ever was Jeanne Calment, a French woman, who lived to 122 years and 164 days.

KEYWORDS Population, aging, elderly, centenarians