The dietary supplement slowed tumour growth and boosted the effects of immunotherapy to destroy cancer in tests on mice.

Susan Rau has been taking a supplement every day for the past 10 years to slow the progression of her macular disease, which impacts up to two million Australians.

“My mother had late stage macular disease and she had lost quite a lot of her central vision as a result,” Rau told 9News.

One of the key ingredients is zeaxanthin.

It’s found naturally in dark leafy vegetables and many other foods including corn, tangerines and egg yolks.

That same nutrient, commonly used to protect vision, could also help the immune system fight cancer.

Researchers from the University of Chicago identified zeaxanthin in a large library of other nutrients and compounds.

In mice, the dietary supplements slowed tumour growth and when combined with immunotherapy, the effects were more significant, according to the researchers.

Experts here in Australia are curious.

“I think the results are really interesting, but all we know at the moment is it has been tested in mice and in cells in the laboratory,” said Lifehouse Cancer Centre Associate Professor Kate Mahon.

“It’ll be great to see it has a benefit in humans but we really need to test that in clinical trials first to find that out.”