Claire Foy is sharing her "gross" experience with parasites after taking a trip abroad. The Crown actress, 41, revealed that she stopped drinking caffeine "quite a few years ago" because she "had parasites" during an appearance on the "Table Manners With Jessie and Lennie Ware" podcast on Tuesday, February 3. Hosts Jessie and Lennie Ware were curious about Foy's parasite discovery and whether she found out through a blood test or stool test. "Yeah, the gross stuff," Foy divulged before she was asked what kind of "issues" in particular she experienced with her stomach. "I kept losing weight and I didn't know what was going on," Foy explained of what raised suspicions that she was dealing with an infection. "I was just like, 'I'm eating everything.' I was so hungry." How a 'Stressful Role' Led to Daisy Ridley's Graves' Disease Diagnosis Foy believes she first got the parasite in Morocco and had been living with it for "at least five years." "They travel as a pair. I got told by the doctor, gross, absolutely rank. It's disgusting," she continued. Claire Foy VALERIE MACON / AFP Parasitic infections are "illnesses or conditions caused by parasites living and reproducing in your body," and "need another living thing (a host) to get the nutrients they need to survive," per Cleveland Clinic. Symptoms can include diarrhea, vomiting, rashes, fatigue and nausea. Foy explained that she changed her eating habits to help fend off the parasite. "That's why I gave up caffeine. I basically had to go on this diet, and because I didn't want to take really hardcore antibiotics and stuff like that, I took all this little gross stuff, and part of that was giving up caffeine," she shared. "Once you give it up, it's such a mission to give it up." Foy admitted she used to drink "at least 15 cups of tea a day" and typically two coffees, so cutting caffeine completely from her diet was a huge adjustment. Claire Foy Aurore Marechal/Getty Images Parasitic infections can be spread through contaminated drinking water, undercooked or contaminated food and insect bites, according to Cleveland Clinic. Some of the most common parasitic infections include malaria, toxoplasmosis, head lice, giardiasis and pinworms. People who are at a higher risk of parasitic infections are young children and those with compromised immune systems. It is estimated "3.5 billion people are affected and that 450 million are ill" from intestinal parasitic infections globally, per Frontiers in Parasitology, with a majority of the estimated infections being children. Further on in the podcast episode, Foy also shared that she suffers from an autoimmune condition. "This is my big secret, I feel like I'm in The Traitors or something, and I'm letting everyone know that I'm related to someone," she quipped. "I don't actually eat gluten or sugar except when I go out for dinner." Foy explained she does make some exceptions to her rule, like enjoying dishes that include gluten and sugar at Christmas dinner, a non-negotiable, each year. "It doesn't have an impact on me," she said of her diet restriction. "It's just because I have an autoimmune condition, so I should avoid anything which causes more inflammation." (Foy did not specify which autoimmune condition she has.)