“There were people in my life at onetime that really did say, ‘You couldn’t really do the activism thing if you wanted to be an actor,’” said Alicia Silverstone, 43, who after Aerosmith’s “Cryin’” video and her role as Cher Horowitz, the spoiled and charming teenager in the 1995 coming-of-age hit “Clueless,” became a Hollywood “It” girl.

After the success of that film, Ms. Silverstone endured an iteration of what was not yet called body shaming when she played Bat Girl, and shrank back somewhat from public life. “I just loved acting,” she said. “I never expected to be famous. I didn’t know what it meant.”

At 21, she began pursuing another interest: veganism, which she had tried off and on since she was 8 years old. She has written a best-selling cookbook, “The Kind Diet,” and been frequently interviewed, including by The New York Times, about her “green” beauty routine.

The sideline, though, came with some side eye. She faced criticism for putting her son, Bear Blu, on a vegan diet and “bird-feeding” him. (Although vegan diets are controversial for children, this is not settled in the medical community. A spokesperson for Ms. Silverstone wrote in an email that he “chooses to eat vegan.”) And again when she wrote in her second book, “The Kind Mama,” a diet- and lifestyle-based parenting guide, that her son, who was a baby at the time, had “never had a drop of medicine.” Ms. Silverstone — like other celebrities, including Jessica Biel and Jenny McCarthy — has made anti-immunization statements. (“She uses critical thinking when it comes to medical decisions and feels it’s important to make informed decisions,” her representative wrote.)

“People said lots of different things, and I was sort of ‘the freak,’ and I guess I’ll take pride in that because it is hard to be the person that’s speaking out, and it is hard to be the person that is saying the thing that isn’t what everybody else wants to hear,” she said.

Experts agree that you should give your children medicine when needed. Anti-vaccine sentiment, which dates back to at least the 1970s, has gotten louder in recent years. Vaccines prevent diseases, and people who don’t vaccinate their children put everyone at risk.

At 31, Ms. Silverstone found an agent who encouraged her to only take on projects that she loved. She had married Christopher Jarecki in 2005 (they divorced in 2018), and their son was born in 2011. She took on a few projects a year, some lower profile, as well as “Vamps,” another movie directed by Amy Heckerling, the writer-director of “Clueless.”

“I feel like I’m just following my bliss with work going wherever it feels interesting and wherever I get to do something fun,” Ms. Silverstone said.

In 2017, she took on supporting roles in films like Yorgos Lanthimos’s psychological thriller, “The Killing of a Sacred Deer”; “The Lodge,” a horror film; “Book Club,” a senior rom-com; and in the short-lived TV comedy series “American Woman.”

Most recently she portrayed a struggling realtor who convinces herself she and her husband need couples therapy in the dark comedy “Bad Therapy,” which was released in mid-April.

In May, she starred in the musical remake of the 1983 teen rom-com “Valley Girl,” as the adult version of the titular character, and this July, she’ll have a supporting role in Netflix’s family-friendly series “The Babysitter’s Club,” as the mother of one of the entrepreneurial young girls, Kristy Thomas.

‘Everything Back to Diet’

Ms. Silverstone committed to veganism out of her love for animals, particularly her dog Sampson, a rescue Rottweiler mix. “I realized that when I was petting his leg, that leg felt the same as the sort of chicken breasts I might be eating, or whatever animal I was eating,” she said. “And I started to wonder what my leg might taste like if somebody ate it.”

Formerly associated with hippies and animal rights protests, the vegan diet has become more mainstream. thanks to concerns about climate change and the wellness movement.

Ms. Silverstone said eating vegan cleared up her acne, helped her lose weight and ditch her asthma inhaler, and gave more energy than ever before. It felt like “great karma” to her. It also presented her with a business opportunity.

Besides the books, she founded, with Garden of Life, Mykind Organics, a line of organic, non-G.M.O. vitamins.

“I’ve had these amazing experiences where people tell me on the street say, ‘I had lupus, I suffer from MS, I have chronic migraines,’” she said. “Or even, ‘I had a really bad heart, I was on heart medication.’ Or ‘I had thyroid medication.’ All these things that people, then, with their doctor, end up not needing anymore because they changed their diets.”

From her Los Angeles home, Ms. Silverstone has been promoting the GoFundMe project Frontline Responders Fund on Instagram to help get personal protective equipment to those in need, and making donations to the designer Christian Siriano, a friend, who has turned his own space into a massive factory.

Every time Ms. Silverstone asks Mr. Siriano for masks on behalf of her nurse friends and their hospitals, he adds them to the list and delivers. “It’s really good to see how much people are all coming together on this,” she said.

She has also been mourning her friend, Mark Blum, the actor whom she worked with on the film “Sister of the Groom.” He died of Covid-19 at 69 in March. “It’s a really sad, scary time for so many people,” she said.

Her daily routine involves sensible self-nourishment. “I always bring everything back to diet,” she said. “When I don’t eat well, I don’t feel well, and then my moods go all over the place.” Ms. Silverstone has been eating meals filled with fresh herbs, greens, miso soup and ginger tea. She has found comfort in cooking, of course, but also in daily long walks, yoga, writing in a journal and meditation.

She has also been focused on finding activities to do with Bear Blu, now 9, when he’s not with Mr. Jarecki — like bouncing on the mini trampoline, dancing or jump roping. “My son and I take baths together, and when he’s not with me, I take a bath and that really feels nourishing and comforting,” Ms. Silverstone said.

A Quarter-Century Since ‘Clueless’

She is still amazed by the “brilliant genius” of Ms. Heckerling. “It’s generational,” Ms. Silverstone said. “The people that were watching it when it came out have shared it with their children, and so it just keeps going and keeps living. I don’t know why that happens to some movies and others it doesn’t, but I’m so grateful to be a part of it.”

In 2017, she introduced a screening of the film at the Hollywood Forever Cemetery and took her son to see the movie for the first time. “I didn’t want to miss out on this opportunity to show him the movie on the big screen like that with 4,000 people outside,” she said. “It just felt like a moment.”

For her, what’s most memorable about the film are the costumes that make “entrances.” After filming, she even kept some of her favorite items like Cher’s Mary Janes, but she’s since given all of the items away. Back then, Ms. Silverstone said, she had “no style” and wore the same green T-shirt and jeans every day for four years.

When asked which actor should play Cher in a reboot, Ms. Silverstone laughed. She’s far removed from the film that once made her a star: “I’m like a grandma at my house who’s going to help climate change and raise my son.”