Today, the Centers for Disease Control and Prevention recommends that every woman of reproductive age get at least 400 micrograms of folic acid, a B vitamin, every day. The CDC can make this recommendation because of the groundbreaking work of scientist Lucy Wills. In the 1920s, her work in India led to the discovery of the substance. Friday would be her 131st birthday, and it’s being celebrated with a Google Doodle.

Wills was born in 1888, near Birmingham England, and in 1911 became one of the first women in the country to get degrees in botany and geology from Cambridge University.

In the 1920s, while working as one of the few female medical research scientists in the United Kingdom, she became aware that poor female textile workers in India were suffering in large numbers from anemia (deficient red blood cells) during pregnancy. Anemia during pregnancy causes fatigue, potential heart problems, and diarrhea, and can be fatal.

The discovery of the “Wills Factor” led to the discovery of folic acid

First, Wills discovered the anemia wasn’t caused by a pathogen (a bacteria, virus, etc.). “Wills made an exhaustive search for pathogens in feces from the women with anaemia,” a 1988 article in the Asia-Pacific Journal of Public Health recounts. But “no evidence of an infective cause could be established.”

Upon investigation, it seemed wealthier women weren’t getting symptoms of anemia as often, so Wills wondered if the anemia was linked to nutrition.

Her studies in rats suggested two things seemed to help: liver supplements and a spread called Marmite. It’s made from brewer’s yeast (that is, after the yeast finishes its work making alcohol, it can be concentrated and eaten), and it’s especially rich in B vitamins. It’s super salty — one of those foods that baffles American tastebuds but is loved abroad.

Wills then went back out into the field, testing the effectiveness of liver supplements and Marmite supplements in pregnant Indian women. They both worked. She treated several anemic women with the Marmite, and the improvement “was amazing,” the Asia-Pacific Journal writes. “They experienced a quick return of appetite ... and an increase in the red cell count by the fourth day.”

Her results were published in a 1931 edition of the British Medical Journal, where Wills admitted she didn’t know what, exactly, in Marmite or the liver supplement was responsible for the difference.

“At present it is only possible to state that in Marmite, and probably in other yeast extracts, there appears to be a curative agent for this dread disease which equals liver extract in potency, and has the advantage in India of being comparatively cheap and of vegetable origin,” she concluded. In Marmite, she had discovered a cheap supplement (at least cheaper than liver) to improve the lives of pregnant women and their babies.

That secret ingredient would be dubbed “the Wills Factor” until 1941, when folic acid — the specific substance that made the difference — was first isolated from spinach. The discovery of the Wills Factor, a 1964 obituary in the BMJ explains, was a “simple but great observations” and a landmark “in the history and treatment of nutritional anemias.”

Folic acid is one of the few nutritional supplements that work

Since Wills’s discovery, scientists have learned that folic acid doesn’t just help the mother during pregnancy but also helps the developing child, playing a crucial role in brain development.

My colleague Julia Belluz explains:

In 1991, researchers discovered that folic acid supplementation can prevent neural tube defects, which are problems with the development of the brain, skull, and spine. These issues arise when the neural tube — a key embryonic structure — does not close properly. The two most common neural tube defects are anencephaly, where the baby is born without parts of the brain and skull, and spina bifida, in which the spinal cord and backbone don’t develop properly. Babies born with anencephaly usually die soon after birth, and spina bifida can lead to lifelong disabilities.

Still, too few women take folic acid supplements. “Folic acid [is] one of the (rare) exceptions where there’s really, really strong evidence” for taking a dietary supplement, Belluz writes. Most nutrition supplements don’t provide many benefits.

In her life, Wills was known for a sharp wit. “Though impatient with laziness and with half-baked opinions, she was compassionate to other human failings,” her obituary in the BMJ reads.

She dedicated much of the rest of her life to working on the links between nutrition and illness, traveling the world in the hope of helping communities grow healthier with nutritional supplements.