However, experts still recommend incorporating a variety of luteolin-rich foods into your diet, such as broccoli, onions, and olive oil.
Do you want to keep from going gray? Scientists are investigating how eating a rainbow of foods might be able to help.
In a new study, luteolin -- a plant compound with antioxidant effects found in broccoli, carrots, onions, and other vegetables -- suppressed the process of hair graying in mice. The research was published in December in the journal Antioxidants.
The results are fascinating, especially since luteolin is so common in the human diet, Joe McCord, PhD, retired professor of medicine at the University of Colorado Anschutz Medical Campus and founder of Pathways Bioscience, told Health. The compound could be a strong candidate for further anti-aging research, he said.
But, experts cautioned, just because luteolin helped mice from going gray, it may not necessarily do the same thing for people.
Here's a look at what the study revealed about luteolin's potential effects on hair color and whether it's worth incorporating more of the compound into your diet.
Nearly all plant foods contain antioxidants, which are chemical compounds that help remove harmful free radicals from our cells. Luteolin is one such chemical helper.
With these potential skin aging and antioxidant properties in mind, the researchers behind the new Antioxidants study tested whether luteolin and two other antioxidants would have any effect on hair graying in mice.
Using mice bred to develop age-related gray hair like humans, they treated groups with either luteolin, hesperetin, or diosmetin daily for 16 weeks. Mice received either internal or external treatments.
After the 16-week period, the mice treated with luteolin retained significantly more of their dark fur than those treated with the other antioxidants -- regardless of whether they received internal or external treatment.
Their more youthful look appeared to be related to luteolin's positive influence on proteins called endothelins. These proteins help maintain melanocytes, the cells that contain hair pigmentation -- so more melanocytes equals more color (and less gray) in hair.
These study results are well and good for mice, of course. But does this mean luteolin will have the same effect on human tresses?
Other studies have suggested similarities in how gray hair develops in both mice and humans. Specifically, it does seem that graying for both parties has something to do with endothelial dysfunction in melanocytes.
These melanocyte cells "fail" as we age, and they stop functioning earlier than the cells responsible for hair growth. This explains why people tend to experience graying, then thinning hair.
But why these melanocyte cells stop working in the first place is certainly up for debate. Graying hair in humans is incredibly complex -- hormones, stress, and other factors are involved.
"While the research suggests that luteolin may impact pigmentation pathways, human hair follicles function differently," Kristina Collins, MD, a dermatologist in private practice based in Austin, Texas, told Health. "Graying is influenced by multiple genetic and environmental factors."
In fact, genetics likely play the biggest role in when -- or to what extent -- a person's hair turns gray, Collins explained. Looking at your parents' and grandparents' heads of hair is probably the best indicator of your own graying timeline.
Still, certain external factors may accelerate or decelerate the process, she said.
"Oxidative stress, nutritional deficiencies, and chronic stress have been linked to premature graying," Collins added.
This could support the notion that focusing on what you eat and your lifestyle -- including increasing your luteolin intake -- might be able to stave off hair graying.
However, experts and study authors agreed that the positive findings in mice don't translate to humans, at least for right now.
"Until clinical trials are conducted on humans, it's too soon to say whether luteolin could be a viable solution for graying hair," said Collins.
As exciting as it may be to think that an antioxidant could take the place of hair dye, the science on the subject is far from settled.
Again, because the study wasn't conducted in humans, it's probably not worth heading out and buying luteolin as an anti-graying supplement, said Amidor.
"I would wait for the science before blindly taking a supplement that is not truly backed up by the research -- especially the dosage, length of time to take it, toxicity effects, and any medication interactions, which are all unknown at this time," she explained.
Luteolin does have a long history of being used in dietary supplements, McCord noted, but side effects are always possible.
"Some individuals may experience gastrointestinal discomfort or allergic reactions," Collins said. "As with any supplement, it's best to consult a healthcare provider before adding it to a routine."
On the other hand, there's no harm in adding more antioxidants -- luteolin or others -- to your diet by eating more fruits and vegetables. Research shows that antioxidant-rich diets may have benefits like suppressing inflammation and promoting a healthy gut microbiome.
"There are numerous food sources of luteolin, including celery, green pepper, broccoli, carrots, olive oil, thyme, beets, Brussels sprouts, cabbage, cauliflower, chili peppers, lettuce, and spinach," Amidor said. "As luteolin is found primarily in vegetables -- and only one in 10 people in the U.S. get their recommended daily amount of veggies -- it is just another reason to eat more vegetables."
For most people, hair graying will be ultimately unavoidable -- but sticking with healthy lifestyle choices can promote overall hair health and might even help you keep your color a bit longer.
"Maintaining a diet rich in antioxidants, managing stress through mindfulness or exercise, and avoiding smoking may help slow the [hair graying] process," said Collins.