SHUSHAN CASTLE GREW in Houston, eating healthy meals prepared by her mother and studying The Wall Street Journal with her stock-analyst father. Those early experiences laid the foundation for her future as a top bond trader — and, more recently, as an expert in how to eat for longevity. She’s made an impact in popular thinking about physical and spiritual health, counting Deepak Chopra among her fans. The writer-researcher sees a link between body and soul; eating better food, without Big Agriculture setting the world’s diet, means a healthier planet — and a people harmonizing with their environment.

Author of books on the chemistry of food — Rethink Food and The Meaty Truth — Castle, 56, explains that after years on Wall Street, her career “pivoted, because I wanted to make a direct difference in the world.” Castle went on to earn a masters in environmental management and water, and got involved with global environmental groups.

After interviewing experts galore, the consensus was that all diseases start with inflammation, and healthy living can be as easy as avoiding inflammatory foods like meat and dairy. Physicians reaffirmed the need for her books. “I began to create a resource describing the how and why of food and diseases,” says Castle.

First came Rethink Food, with insights from docs and athletes on how to eat for the prevention and reversal of diseases. Her second book, also co-written with Amy-Lee Goodman, The Meaty Truth, was born from Castle’s views on climate change caused by agricultural practices. Think growth hormones and factory farming.

“Traveling the world and getting to know people in many countries, I discovered... one underlying solution for cures for cancer, diabetes and other diseases,” says Castle, a vegan. “I saw so much suffering with diseases, which I know are mostly preventable through our food choices.”

The mother of three grown sons gleaned that the American Medical Association and the American Pediatric Association approve of a diet with zero meat and dairy for excellent health. “I learned from doctors at Harvard and Cornell that the food pyramid was designed by the meat and dairy industries,” she says.

Castle receives tons of emails from grateful readers. “I receive endless letters from people describing how they took out inflammatory and acidic foods, and their diseases went into remission.” She’s heard from cancer survivors who went into remission without medical treatment.

Her work has also gotten notice from President Bill Clinton, who invited her to round-tables with Bill Gates, Queen Noor and other leaders to discuss water remediation and food scarcity. But perhaps most validating is Deepak Chopra’s recent endorsement. “He posted a 14-minute recommendation of both books,” she says. “He [said] they are extremely beneficial to excellent health and peak performance.”

Not one to sit still — except for a daily meditation — Castle, an avid hiker, is penning another book and producing documentaries, working with Oscar winners dedicated to helping protect the global environment. “I thrive while multitasking,” she says. “And I have a wild passion for making a real difference.”