On her YouTube channel, Mari Lopez claimed that her raw, vegan lifestyle “cured” her of breast cancer. But when the disease spread to her blood, liver and lungs, she decided to try chemotherapy and radiotherapy. 

It appears, however, the intervention was too late, as her niece Liz Johnson has revealed that Lopez died of breast cancer in December 2017.

Lopez told viewers of her YouTube channel Liz & Mari, which she hosted with Johnson, that her faith in God and diet consisting entirely of plant-based products rid her body of cancer in four months. She also claimed in one video that she was “healed by God" and "used to live a gay lifestyle," according to the website Babe, where Johnson confirmed her aunt's death. Neither claims have any medical or scientific basis.

Since launching the arguably niche channel in 2015, the duo amassed 11,761 subscribers and their videos garnered almost 1 million views. In a video entitled Cancer Transformation FAQ, Lopez recounted her experiences of a so-called “90-day juice cleanse” and explained her rejection of science-based medical treatment.

"It's my choice, I've been okay, I haven't died, I haven't gotten to the hospital. I am going to continue on this path of going natural," Lopez said. "It's [cancer] over, it is done with, I am healed. I feel it in my spirit and in my body."

Lopez explained in a separate video called Stage 4 Cancer Natural Transformation that God directed her towards the foods that would cure her disease.

But as her condition deteriorated, her sister (Johnson’s mother) encouraged her to eat meat and try chemotherapy and radiotherapy.

In an interview with Babe, Johnson pinned her aunt’s death on the scientifically unfounded idea that cooking her food in a microwave and reintroducing meat into her diet is what killed her. 

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“My aunt was very against the microwave because of cancer-causing issues with that, and my mom would cook her things using the microwave,” she told online magazine Babe.

When Lopez realized she would die from cancer, she asked her niece to remove the videos claiming veganism could beat the disease. However, Johnson refused, claiming that her aunt died because she abandoned her raw diet. 

Lopez’s death highlights the dangers of so-called “alternative” or “complementary” methods for treating cancer, which are not backed by science and are therefore not accepted by mainstream medicine.

The American Cancer Society warns that the wide variety of products, practices and systems fall under these umbrella terms are “nearly all unproven," as methods that work are quickly tested and adopted by clinicians.

It added: “Be very suspicious of any treatment that says it can cure cancer. Claims that a treatment can cure all cancers or that it can cure cancer and other difficult-to-treat diseases (including chronic fatigue, multiple sclerosis, AIDS, etc.) are sure to be false.”

“There is absolutely no evidence to suggest that any diet will cure cancer,” registered dietitian Aisling Pigott told Newsweek.

“A cancer diagnosis places both emotional and physiological stress on a person’s health. While some people may find some positive changes empowering, drastic or extreme changes could have a detrimental effect on nutritional status and survival outcome.

She added that while a planned, vegan diet can be healthy, it cannot prevent or treat cancer. 

Pigott believes the relatively large number of viewers who watched Johnson and Lopez's channel proves that such content should be cracked down upon as it can harm the public.

“As dietitians, we are accountable and bound to a professional code of conduct which we must adhere to in order to maintain our registration," she said. "Although many of these YouTubers and self-proclaimed nutrition experts do not have any codes of conduct, I would argue they have a personal responsibility not to cause harm."

Johnson declined to give any further information about her aunt's death.