Jerusalem – Birthright Israel has seen its share of controversy: complaints that the free trip to the Jewish state is too focused on marrying off young Jews; students challenging Birthright officials to take a stand against a travel ban for foreigners who support an Israel boycott; and calls to renew visits to Arab Israelis.

But what many say can be a life-changing trip for young Jews can be a life-saving one as well, it turns out.

For the past 14 years, the Florida-based nonprofit Gift of Life has offered presentations to Birthright’s North American participants about the importance of becoming a potential bone marrow or stem cell donor and the opportunity to enter its registry.

So far, 1,551 Birthright participants have been classified as potential matches to current patients on the registry and 205 have donated either bone marrow or stem cells. In all, more than 52,000 of the nearly 400,000 North Americans who have come on Birthright have been swabbed, according to Molly Livingstone, Gift of Life’s Jerusalem-based outreach coordinator. Another 11,000 Israel-based North American yeshiva and seminary students have also been swabbed. Of these, 492 are potential matches and 86 have donated bone marrow or stem cells.

At a recent Gift of Life fundraising event in Jerusalem, 2014 Birthrighter Zoe Miller, who was swabbed during her trip, met for the first time with the Miami cancer patient whose life she saved.

After meeting Miller, Ann Hearin, now 40, who had a rare form of lymphoma, told the Sun Sentinel, “If my donor hadn’t done what she did, I wouldn’t be here for my family, my husband and my daughter, who was only 2 months old when I was first diagnosed. I don’t know if Zoe will ever understand the magnitude of the gift she’s given me, but she’s a part of me now.”

Miller told The Jewish Week that she was “overcome with emotion” during the reunion. “Before this meeting the impact of what I’d done hadn’t really registered.”

Two years after her mouth swab, Gift of Life called Miller to say she was a potential match for a cancer patient and asked her to undergo some blood tests.

While the news was exciting, Miller was also worried.

“Whenever I give blood, I pass out,” she explained. “But when I talked to my mom and my friends they said I should do it, and I am so glad I did.”

Following an eight-hour extraction process, Miller’s stem cells were donated to Hearin; the transplant saved her life.

Gift of Life founder Jay Feinberg established the organization in 1991 after a bone marrow transplant cured his leukemia. Funding for the Birthright information and swabbing sessions comes from the Adelson Foundation and other foundations and individuals.

Zohar Raviv, international vice president of education for Birthright Israel, said giving its participants the opportunity to be part of the registry and to potentially donate bone marrow or stem cells is a hands-on way for them to embrace “the value of mutual responsibility and a sense of Jewish peoplehood and commitment” that Birthright is trying to impart.

Peter Schottenfels, who went on a Birthright trip in 2007, said he agreed to be swabbed “because it seemed like the right thing to do. It seemed like it could mean a lot to someone.”

Even so, he said he was surprised when he learned he was a potential match. “I was at work and I’d almost forgotten I’d been tested,” said Schottenfels, who at the time was entering his senior year of college at the University of Michigan.

Now a 31-year-old public relations professional in Manhattan, he said he “feels lucky” he could save the life of Etty Batzelai, a 57-year-old Israeli attorney and physician.

Batzelai, who had leukemia, said that since receiving Schottenfels’ bone marrow in April 2014, she has experienced some graft vs. host complications, but that they are under control.

“I’m alive. I see my children every day,” said Batzelai. “I thank God every day that I live. I’m happy and thank Peter every day. He saved my life.”