Herbal supplements were supposed to make them healthier. Instead, they got sick

Originally published in The Guardian

Fernanda Thompson was a healthy 40-year-old when she began taking turmeric in 2020. Online, people were saying the pungent yellow spice could make everyone a little bit healthier. So she began putting half a teaspoon, about 2.5 grams, into her morning smoothie, hoping to reap the benefits of curcumin, the compound responsible for turmeric’s anti-inflammatory, anti-cancer, anti-oxidant halo.

“It was Covid time,” says the Florida resident, who is a stay-at-home mom, and she wanted to boost her immunity. “I was healthy. And then I guess I tried to be healthier,” she says.

In 2021, a routine blood test revealed Thompson’s white blood cell count was oddly low. She was referred to a hematologist and an ultrasound showed an enlarged liver.

Thompson felt physically fine, but began monitoring her health more closely with both her doctor and a hematologist, getting regular blood tests that showed consistently low white blood cells. She feared with every follow-up that her doctors would make a serious diagnosis, like leukemia.

In 2024, after three years of health anxiety, Thompson came across a blogpost by gynecologist Dr Jen Gunter titled “The Trouble with Turmeric”. In it, Gunter challenges the popular belief that turmeric is a completely safe, natural panacea. She points out that some of the most frequently quoted data on turmeric’s benefits are derived from discredited and low-quality studies. When you take turmeric, you are “paying to play the liver injury lotto with no quality data to prove that the product can help you meaningfully”, Gunter writes, citing research showing that to some people, turmeric can be toxic to macrophages, a type of white blood cell, and may contribute to iron deficiency.

Attributions of causality between blood abnormalities or organ damage and supplements or natural medicines are notoriously difficult for general practitioners to provide, due to factors including the variable composition of supplements and their lack of research and regulation. However, there is data linking turmeric to liver injury – as of 2022, at least 10 cases in the US and 18 in Australia, including one fatality.

Thompson immediately stopped taking turmeric.

“Six months later I did my blood test again and my white blood cell count was normal,” says Thompson, who ended up paying $1,275 out of pocket for her tests. Her doctor said they would never know if the cause was turmeric or something else, Thompson remembers, “‘but don’t take it again’”.

This story originally appeared in The Guardian, October 2025. To read the full story, click here.