The fat found in fast food can help protect against the deadliest form of skin cancer, a study claims.
Experts found that palmitic acid, which is in products such as burgers and cookies, fuels a protein involved in the pigmentation process to help protect against harmful skin cancer mutations.
While fast food can have harmful effects on the heart and brain, it could prevent melanoma, a deadly skin cancer.
Rates of people being diagnosed with melanoma have increased the past 30 years in the United States. The American Cancer Society estimates close to 10,000 people will die from the cancer this year.
Experts said this breakthrough in research could lead to a drug for those who are red hair, fair skinned or have consistently tanned, all of whom are more at risk to get skin cancer.
Researchers from Boston University in Massachusetts discovered palmitic acid, a fat found in fast food, controls the activity of the MC1R gene.
This gene, also known as the 'ginger gene', affects the type of melanin pigment it produces for the skin.
These variants give redheads their signature hair color, freckles, pale skin and a strong tendency to burn in the sun.
Exposure to ultraviolet light, either from the sun or from sunbeds, can damage DNA and cause mutations that can lead to skin cancer.
Mice in the study with the gene mutations were given palmitic acid.
It increased their skin pigmentation and prevented melanomas.
Professor Rutao Cui, of Boston University in Massachusetts, said the MC1R gene 'has a crucial role in human and mouse pigmentation.'
Its activation in human skin cells grown in the lab stimulated melanin production and boosted DNA repair after ultraviolet irradiation.
'Individuals carrying MC1R variants - especially those associated with red hair color, fair skin and poor tanning ability - are associated with higher risk of melanoma,' Professor Cui said.
The findings show why individuals with red hair are more prone to the disease.
Professor Cui said: 'The results highlight a central role for MC1R palmitoylation in pigmentation and protection against melanoma.'
Palmitic acid is a fatty acid, or lipid, present in saturated fats but its role in darkening skin was unknown until now.
This fatty acid is normally found in fast food such as burgers, fries and cookies.
'Collectively, our results highlight a central role for MC1R palmitoylation in protecting against melanoma,' Professor Cui said.
'It might be a potential clinical prevention strategy for melanoma in individuals carrying red hair color variants.'
Professor Ian Jackson and Dr Liz Patton, of the Medical Research Council's Human Genetics Unit at Edinburgh University, reviewed the findings for the journal, said red hair is 'increasingly capturing the attention of scientists.'
They said: 'Some versions of the MC1R protein are associated with red hair and an increased risk of developing a skin cancer called melanoma. It emerges that a lipid that binds MC1R might provide a target to reduce this risk.
'Interestingly, many natural products contain palmitates. A palmitic acid ester in oil from the lotus flower enhances melanin production when added to cells grown in the lab.
'Coconut oil is also rich in palmitates. Perhaps it is time to investigate the anecdotal claims that coconut oil can help you to tan?'
Close to 90,000 people are expected to be diagnosed with melanoma in the United States this year, according the American Cancer Society.
The numbers have grown over the past 30 years.
While melanoma only makes up for one percent of skin cancer diagnoses, it is the deadliest form and is expected to kill close to 10,000 people this year.