Joey Graziadei finally put an end to the mystery that left many fans puzzled as to why his eyes are yellow.

"The Bachelor" Season 28 star revealed that he has Gilbert syndrome, a harmless liver condition that can impact eye color. In an Instagram video uploaded Thursday, he explained that he was diagnosed in high school after being sick for over a week. Blood work, several doctor visits and a liver ultrasound led to his diagnosis.

"At the end of the day I am told that I am healthy. It is something that affects the whites of my eyes. It makes it have those jaundice levels, which is why they look a little bit more yellow," Graziadei said. "It's something I want to pay attention to more going into this year. I want to get my health right.

The 28-year-old tennis instructor said that he is healthy and that his condition simply requires him to pay more attention to his fluid intake.

"It is worse when I have stress or lack of sleep, which happens on a TV show," he said. "I do appreciate everyone looking out for me and wondering if I'm okay. To my knowledge I'm as okay as I can be."

What is Gilbert syndrome?

Gilbert syndrome is a common genetic condition in that prevents the liver from properly processing bilirubin, which is made by the breakdown of red blood cells.

The harmless inherited condition is often discovered by accident when blood tests reveal a rise in bilirubin levels, according to the Mayo Clinic. Gilbert syndrome does not require treatment.

Around 3% to 7% of Americans have Gilbert's syndrome, and the condition is more common in men than women, the Cleveland Clinic reported. Only one in three people with the condition experiences any symptoms.

How Gilbert syndrome affects eye color?

Gilbert's syndrome can cause the occasional yellowing of the skin and whites of the eyes because of too much build-up of bilirubin in the blood, according to the Cleveland Clinic. This side effect is not harmful.

Gilbert syndrome symptoms

Symptoms of Gilbert syndrome include the "occasional yellowish tinge of the skin and the whites of the eyes," according to the Mayo Clinic.

For people with Gilbert syndrome, other common reasons for the increase of bilirubin levels include:

• Dehydration
• Illness, like the cold or the flu
• Fasting or low-calorie diet
• Menstruation
• Stress
• Strenuous exercise

Who is Joey Graziadei?

Graziadei is a teaching tennis pro from Collegeville, Pennsylvania, according to his bio from ABC.

He made his reality TV debut in Season 20 of "The Bachelorette" with Charity Lawson, where he was the runner-up who lost to Dotun Olubeko. In August, he was announced as the next lead of "The Bachelor" during the season.

Who does Joey Graziadei end up with? (Spoilers)

Graziadei gets engaged to account executive Daisy Kent, 25, from Becker, Minnesota, according to well-known Bachelor blogger Reality Steve.

Kent, Kelsey Anderson and Rachel Nance are Graziadei's final three, with Kent and Anderson advancing to the finals, Reality Steve says. According to the blogger, Graziadei and Kent got engaged in Tulum, Mexico, at the end of the season.

Contributing: Emily DeLetter and Victoria Moorwood