Redheads may need more anesthesia

Q: When I told my dentist that I'm having knee surgery this summer, she said to be sure the surgeon knows my hair is naturally red and not dyed. She said redheads respond to pain drugs differently, and she actually has to use more anesthetic on me. Is that really true?

A: This sounds like the kind of weird health claim that goes viral on social media, so it's not surprising you might be skeptical.

Yet, there is both research and anecdotal evidence to support the idea that people with naturally red hair can have different requirements when it comes to drugs that control pain. There is a school of thought that says redheads require more local anesthetic to manage pain, as well as increased amounts of general anesthesia to induce unconsciousness, than the rest of the population.

That said, it's a somewhat recent and still-evolving concept. It's also a bit controversial, with its fair share of detractors.

While more research is needed in order to state definitively if this theory about redheads is either right or wrong, we can help lay out some of the thinking behind it.

Less than 2% of the world's population are natural redheads. That makes red the rarest of hair colors. Red hair results from variants associated with the MC1R gene, which provides the instructions that lead to each person's individual pigmentation. In addition to hair color, this gene influences someone's skin color, their response to UV light and their risk of developing melanoma. The gene also plays a role in pain perception.

Someone with red hair has two copies of the MC1R gene, receiving one from each parent. The gene also carries a certain mutation in most people who have red hair. It's this variant that has been identified as playing a role in why redheads may respond to pain drugs differently than others. But research into the specifics has yielded sometimes contradictory results.

A pair of small studies conducted in the early 2000s focused on tolerance to pain. One found that people with MC1R variants are more sensitive to heat and cold. However, in a separate study, people with MC1R variants were less sensitive to stimulus from electrical currents. This was followed by a small study published in the journal Anesthesiology, which found that women with red hair required up to 20% more anesthesia to keep them sedated than did women with dark hair. A subsequent study, conducted in 2009, found that redheaded patients required higher levels of anesthetics to numb the pain of dental procedures. This backs up your dentist's experience with your own pain-control needs.

And to add to the mixed nature of this line of research, a recent study linked differences in pain sensitivity to MC1R variants that are separate from those that cause someone to have red hair.

So where does this leave you as a red-haired patient? As we mentioned earlier, there is anecdotal evidence, both from patients and clinicians, regarding red hair and pain response. That makes it worthwhile to talk about the issue with your surgeon, and to let him or her know about your dentist's experience with your unique needs regarding pain suppression.

Coffee break

Q: Where do we stand on coffee these days? It seems like there's always a new study that says either coffee is healthy or that it's bad for you. I've even read that coffee helps your brain stay sharp. I love my daily morning cup and hope that the most recent news about coffee is good.

A: For as long as people have been drinking coffee, they have been arguing about it. Historians trace coffee's origins to wild plants found in Ethiopia, and its emergence as a global beverage to the mid-1400s. Over the centuries, a variety of religious, political, economic and health-based bans on coffee have been enacted, all to no avail.

Today, people worldwide drink an estimated 2.25 billion cups of the beverage each day. And instead of arguing about coffee, we have switched to studying it. In the earlier days of coffee research, enthusiasts endured alarming conclusions that linked their morning cup to health problems such as heart disease, high blood pressure, pancreatic cancer and asthma. It was later revealed these studies included participants who smoked, and the adverse effects probably arose due to tobacco use, not as a result of coffee consumption.

Newer research is uncovering a sometimes surprising range of potential health benefits for moderate coffee drinkers. These include a lower risk of health problems including Type 2 diabetes, heart disease, chronic liver disease, Parkinson's disease, depression, and liver and endometrial cancers. And while the stimulant effect of caffeine is a major reason for coffee's popularity, it's unlikely it plays a role in health benefits. Scientists suspect that credit goes to the dozens of other complex compounds that coffee contains.

In recent months, new research with more good news about coffee has been published. A study in the journal Frontiers in Aging Neuroscience, published last fall, examined the effects of coffee consumption on cognitive impairment in 227 adults in their 60s. None had memory problems. The health questionnaire they were issued included questions about how much coffee each person drank and how often. Cognition was assessed every 18 months over the course of the 10-year study. When the research concluded, the data suggested a link between daily coffee consumption and lower and slower rates of cognitive decline and cognitive impairment.

A recent study from China linked coffee drinking to longer life. Researchers followed the health outcomes of about 170,000 adults in their mid-50s for seven years. None had cancer or cardiovascular disease. The data showed those who drank a moderate amount of coffee each day — between two and five cups — were less likely to die during the scope of the study. Interestingly, the health benefits extended even to those coffee drinkers who added a teaspoon of sugar to their cup. The use of artificial sweeteners, and the addition of dairy products and artificial creamers, were not addressed.

It's important to remember the caffeine in coffee can interfere with sleep and cause the jitters. And, as we wrote in a recent column, older adults, who often metabolize caffeine more slowly, may have to adjust their habits as they age.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.