Twitter alums are taking over the health-technology sector.

A LinkedIn search revealed that more than 20 former Twitter employees are now at health, fitness and bio-tech start-ups. The vast majority of them joined or founded these companies in the past two years, in the midst of Twitter’s well-documented executive shakeup.

This list includes but is not limited to:

• Former Twitter CEO Dick Costolo, who’s now running a fitness app called Chorus
• Former Twitter industry manager Julie Martin, who’s now working with Costolo as head of partnerships at Chorus Fitness; and ex-Twitter senior product manager Erin Moore, now head of product at Chorus Fitness
• Former Twitter data science leader Jesse Bridgewater, who’s now running the data science team at Livongo Health
• Former Twitter media heads Katie Jacobs Stanton, who now runs marketing at a personal genetics company Color, and Ross Hoffman, now Headspace’s chief business officer
• Former Twitter vice president of sales finance Jeff Dejelo, now running finance at Color
• Former Twitter strategy and operations manager Linda Jiang, now consumer marketing at Color
• Former Twitter vice presidents Elad Gil and Uthman Laraki, who co-founded Color Genomics
• Former Twitter’s senior product director Baljeet Singh who’s now at chronic disease management start-up Livongo Health
• Former Twitter vice president of engineering Nandini Ramani, now chief engineer at Outcome Health
• Former Twitter mobile market manager Charles Wu, now director of product at Catalia Health
• Former Twitter director of global operations Rita Garg, who left the company for a senior business development role at Zenefits
• Former Twitter intern Ray Bradford, now is now the CEO of Spruce Health
• Former Twitter account executive Rick Cerf, now a product manager at Grand Rounds Health
• Former Twitter recruitment manager Mel Heydari, now director of talent at Proteus Health

What’s attracting all these Twitter alumni? Healthcare might be the fifth-largest industry in the U.S., but it’s highly-regulated, notoriously complex and the sales cycles are far slower than in other sectors.

In other words, there are far easier ways to make a buck.

After leaving Twitter, Costolo got into the fitness-tech space for personal reasons. He’s a runner and Crossfit addict, and saw an opportunity to engage others in sports. But he had a few other ideas to explain the interest of so many fellow Twitter alums in health-tech.

“At Twitter, we were always mission-centric,” he said.

So it seemed logical to Costolo that his former colleagues would be attracted to companies with a strong mission.

“In Silicon Valley, we joke that every company thinks they’re changing the world,” he said. “But with health, you can see an immediate impact rather than needing to jump through verbal hoops to convince yourself.”

The other factor is the network effects. Just like the PayPal mafia, a group of high-profile former employees that chose to invest in each other, the Twitter alumni in health care are picking up the best and brightest from their former workplace.

Twitter’s former media chief Katie Jacobs Stanton served on the board of Color Genomics alongside fellow Twitter colleagues Elad Gil and Uthman Laraki before making the decision to join full-time. She subsequently snapped up Linda Jiang and Jeff Dejelo, both from Twitter.

“Yes I do think there’s a network now,” she said. “But we also recognize that the (health) space is wide open and there’s so much opportunity.”

Baljeet Singh, who now works at a diabetes management start-up called Livongo Health, said he was shaped by the “rough patches” at Twitter. At times of intense scrutiny, he recalled that the all-hands meetings reminded him of the company’s mission. “It bound us together and got people fired up,” he said.

“I didn’t want to join a start-up that was doing things your parents used to do for you, like food delivery or laundry services,” Singh said. “I thought that tech could play a much bigger, and more socially impactful role in the world than that.”