Drew Barrymore says her female friendships have kept her "anchored" through the years.Research has shown that having strong friendships is as important as exercise for longevity.However, it can be difficult to make and maintain friendships in adulthood.Drew Barrymore, 49, is grateful that she has supportive female friends to rely on.During Wednesday's episode of "The Drew Barrymore Show," which featured guest Julianne Moore, the talk show host spoke about the strong friendships she shares with the women in her life."I think female friendship has been the thing that probably anchored my life the most," Barrymore said."Most of my friends I've had for 30 and 40 years I'm going to be 50 so it's like my whole life I've known these people," she said. "I trust them implicitly."The "Never Been Kissed" star had a troubled childhood: She was 13 when she entered a youth rehab center for drug use, and she was 14 when she was legally emancipated from her mother.Barrymore said her friends are "very honest" with her and know what she's been through."I feel like not having had traditional family, everything is possible through my female friendships," Barrymore said, adding that they help her get through her heartbreaks "much easier.""Every time I've ever been dumped, my first phone call is my girlfriends. They make it so much better," Barrymore said.In particular, Barrymore has been open about her friendships with her "Charlie's Angels" costars, Cameron Diaz and Lucy Liu.The three of them have made public appearances together over the years, including the premiere episode of Barrymore's talk show in 2020.Barrymore revealed in a 2021 Instagram Live that she was friends with Diaz long before they shared a screen."We met when I was 14 and she was 16. I was working at a coffee house and she was a junior model. She's still my bestie," Barrymore said.There are plenty of celebrity best friends in Hollywood, including Oprah Winfrey and Gayle King, who became friends after a snowstorm in 1976, and Jane Fonda and Lily Tomlin, who have known each other since meeting on set in 1980.Research has found that having good friendships could be as important as exercise and diet for living longer.However, adult friendships can be tricky to form and maintain, Dr. Frederick Smith, a psychologist, told Business Insider previously."As adults, we have many obligations," Dr. Smith said. "We may have responsibilities to our job, family, children, or education. We spend a lot of time doing these things, so we may not have enough time to devote to going out and developing friendships."However, there are ways for people to improve their friendships, he said. This includes practicing healthy boundaries, communicating clearly, and actively working to keep the relationship alive."Both people have to work to maintain it," he said. "Friendship should not be one-sided. If you only call me when you need something, or you only call me when you're going through some type of turmoil, and then I never hear from you, then that's a problem."A representative for Barrymore did not immediately respond to a request for comment sent by BI outside regular hours.