Twice, Jason Vale was diagnosed with cancers that should have killed him. But 30 years after the first tumor was found in his chest when he was 18, Vale is still alive. The reason for his survival is not chemo, radiation, cancer drugs, or surgery, Vale claims. He says he owes his life to a controversial natural product that’s been making headlines for years: apricot seeds.

Vale first learned about the seeds when he was 25 and was diagnosed with renal cell carcinoma, a common type of kidney cancer. He refused any medical treatment and he says he only treated himself with the kernels, eating up to 40 a day. "When I ate the seeds, my tumor shrunk down and when I stopped eating the seeds the tumor grew," Vale said in a voice message sent over text. "I used alternative medicine. That’s why I can’t credit [traditional] medicine, because I didn’t take it when it shrunk."

Some believe apricot kernels can fight or prevent cancer

Vale is not alone in believing that apricot kernels — the soft, almond-like seeds found inside apricot pits — can fight or prevent cancer. The internet is full of accounts written by people who claim apricot kernels have saved their lives. The seeds contain amygdalin, a compound also called laetrile that some people believe has cancer-fighting properties. But amygdalin is actually converted into cyanide in the body, a poison that can cause nausea, headaches, insomnia, and nervousness. Cyanide can also lower blood pressure to unsafe levels and even lead to death. Laetrile was shown to have no anticancer activity in human clinical trials, according to the National Cancer Institute, and its use for treating cancer is illegal in the US.

Apricot seeds have been popular in the US since at least the 1970s, when laetrile was popularized as a cancer treatment. (Hollywood star Steve McQueen famously traveled to Mexico in 1980 to cure his terminal cancer with laetrile, but died within months of beginning the therapy.) The kernels have remained a cult phenomenon ever since, even though they’re known to have caused death in children who ate them. And they’re not the only "superfood" touted for cancer treatment. A quick Google search shows thousands of articles about the vitamin-rich fruits and veggies that are thought to fight or prevent cancer — from kale to broccoli to blueberries to green tea. Though these foods are healthy, the science behind their cancer-fighting properties is murky, experts say. Sometimes there’s no science at all. And often, these foods can even interfere with chemotherapy, radiation, and cancer drugs, putting patients at risk.

"Many people believe that a natural product, herbs, and fluids are safer than chemotherapy radiation treatment," says K. Simon Yeung, a pharmacist and herbalist at Memorial Sloan Kettering Cancer Center and the manager of the About Herbs database, which informs patients on unproven anticancer treatments. "However, we do know that natural doesn’t always mean safe and sometimes they have more side effects than people believe."

"Natural doesn’t always mean safe."

Eating lots of fruits and vegetables can actually help prevent cancer, experts say. But focusing on certain particular "superfoods" is counterproductive, because it encourages people to eat a few foods and ignore others. "Superfoods is a term that seeks to describe food products with, apparently, superpowers," says Casey Dunlop, a health information office at Cancer Research UK. "It’s actually a marketing term. It’s not based on any scientific evidence."

Or sometimes the science isn’t clear cut. Certain vegetables — like broccoli, brussels sprouts, and cauliflower — have been found to help lower the risk of prostate and breast cancer in certain studies, but not in others. Translating small lab studies into actual cancer treatments that work on a large scale is also hard. "Our bodies are a lot more complex than a lab study," says Dunlop. "These findings haven’t translated into big population studies."

In the case of apricot seeds, which contain amygdalin also found in almonds and apple seeds, even a small dose is toxic because of the cyanide. Their toxicity has been known for years. More recently, the European Food Safety Authority (EFSA) — Europe’s food safety watchdog — warned that the seeds are dangerous, especially for children. In its report, the EFSA notes a number of cases of children who were hospitalized for cyanide poisoning caused by apricot kernels, including 260 such cases in Turkey, where the seeds are a common food. A 28-month-old girl died because of high cyanide levels in her blood after eating 10 kernels.

The researchers found that adults should limit themselves to three small kernels a day, and toddlers to one small kernel. But online, people recommend much higher doses. On his website, Vale talks about eating as many as 40 seeds per day. Veronique Desaulniers, who has a website about beating breast cancer only with natural treatments, says the general recommendation is one kernel per 10 pounds of body weight. And Sandi Rog, who has a blog titled "I Beat Cancer With Vitamin B17" — another name for amygdalin, says cancer patients should eat three to six seeds per hour. (Rog didn’t respond to repeated requests for comment.)

When the kernels are chewed or ground, the amygdalin is degraded to cyanide. People who believe in the power of apricot kernels think that this cyanide is only toxic to cancer cells, but scientists say that’s not true. The cyanide is toxic to all cells because it interferes with their oxygen supply — and it is particularly bad for the brain and heart, which require constant oxygen to function.

But devotees of a nutrition-based approach to cancer don’t believe this. How can scientists say that apricot kernels — a natural product — are toxic, when chemotherapy is known for damaging healthy body tissues alongside the cancer cells, they wonder. ToniAnn Vizzi, the vice president of the P4 Foundation, a non-profit organization that helps raise awareness about childhood cancer, says her 18-year-old son takes three apricot kernels a day in his protein shake.

Her son, Gino Vizzi, was diagnosed with chronic myelogenous leukemia (CML) when he was 16. CML is incurable, so Vizzi will have to do chemotherapy for the rest of his life, but in the meantime he’s on an organic diet rich in vegetables, juices, vitamins, filtered water, and probiotics. The diet includes the apricot seeds. "Why not? It’s not gonna harm you," says his mom, ToniAnn. "It’s something that I think God gave us to use and if you’re doing okay with it and it works, why not?"

"The patients want to do everything they can."

The "why not" argument is one that experts see time and again when dealing with cancer patients, who are particularly vulnerable to falling prey to sham "cures." "It’s very difficult because with cancer patients, the patients want to do everything they can," says Adriana Salmon, a clinical dietitian at the University of Texas MD Anderson Cancer Center. "And sometimes they feel like they don’t have control over their treatment and they feel like, 'Oh, if I do this, I’m going to help myself.'" Cancer centers usually offer nutrition advice to patients, both because patients’ interest in alternative medicine is growing and also because eating a healthy, plant-based diet can help cancer patients deal with the side effects of chemotherapy and radiation. But these nutritionists don’t suggest that nutrition alone can cure cancer.

Vale, who refused treatment for his kidney cancer, began selling apricot seeds on the internet as a cancer cure. Eventually in 2000 the US Food and Drug Administration got a court injunction to stop him, and in 2003 Vale was convicted to five years in prison for criminal contempt of the injunction. After his time at the Federal Correctional Institution at Fort Dix in New Jersey, his kidney tumor grew larger until, in 2013, Vale had his kidney removed.

Today, Vale doesn’t have cancer but he eats four to 15 seeds every day, most days, for prevention. His website, Apricots from God, is a mishmash of his own cancer survival story, medical reports about his tumors, newspaper clippings about laetrile, warning letters from the FDA, and testimonials from people claiming to have cured themselves with the kernels. On the upper right corner, a "Store" tab links you to a related website where you can buy herbal products, enzymes, and organic teas. Under a "Cancer Fighters" tab, you can find the apricot seeds. A one-month "starter package" that contains a pound of bitter apricot seeds, supplements like coral calcium tea bags, and a DVD of the film "World Without Cancer" about laetrile, goes for $199.

Even in the face of the evidence that apricot seeds are toxic, even after jail time, Vale remains a believer.