• Jena Martin MD

I don't eat margarine

Updated: May 16, 2019

But I do avoid the sun.





The recent article in Outside magazine written by Rowan Jacobsen, Is Sunscreen the New Margarine? has created a lot of outrage. Which it was meant to do. From the title to the tone, the author is outraged about a lot of medical advice.


I started reading the article thinking I would find flaws with his argument. Surprisingly, I agree with the author's main point - we need moderate natural sun exposure to reduce inflammation, reduce cancer risks and improve our circadian rhythms (via several possible mechanisms including vitamin D and nitric oxide). For many people, the benefits of these factors outweigh the risks of skin cancer.


And, as he highlights in the article, this sort of moderate sun exposure is exactly what experts like the British Association of Dermatology recommend.

From their recommendations:


Reducing UVR skin exposure lowers the risk of skin cancer and ageing. Absolute sun avoidance is not advocated, however, as casual brief sun exposure, well below that leading to burning, helps maintain bodily vitamin D sufficiency. Subjects in whom such exposure for medical or other reasons is contraindicated or impracticable, however, can successfully maintain vitamin D sufficiency through oral supplementation.


None of this is outrageous. But this is not how the author reports the case. The world he rails against has everyone covered head to toe in hats and scarves, white zinc covering noses, shielded by sun umbrellas. I don't think anyone in the medical establishment is advocating for the kind of extreme sun avoidance that the author sets up as the norm. It seems like a straw man argument. In the real world, we have white teenage girls going to tanning salons and growing melanomas in their 20's. We have elderly white patients undergoing eyelid removals for basal cell carcinomas or ear removals for squamous cell carcinomas.


One of the basic premises of this article is that we aren't getting enough Vitamin D. Vitamin D has complex biochemistry. Low Vitamin D levels are both a dietary and a sunlight-related problem - we ingest it and exposure to sun transforms it into an active form. Low Vitamin D levels are associated with a variety of illnesses, from fatigue to internal cancers - but is the Vitamin D low because of the illness or did it contribute to it? Recent studies have shown that supplementation with Vitamin D does not offset the higher rates of disease thought to be associated with low Vitamin D. And, routine testing for Vitamin D in otherwise healthy people is not recommended - although many people continue to pursue it.


To further complicate matters, sunlight does more things than turn Vitamin D to an active form; for example, sunlight activates nitric oxide, a molecule which in turn lowers blood pressure. Much of the article deals with how this effect of lower blood pressure from sun exposure is too important to offset the reduction in cancer risk that less sun exposure brings.


Let's move onto his discussion of skin cancer. I'm a dermatopathologist! I have diagnosed thousands of skin cancers.


Mr. Jacobsen writes:

"Wouldn’t all those rays also raise rates of skin cancer? Yes, but skin cancer kills surprisingly few people: less than 3 per 100,000 in the U.S. each year."

He is right - 'skin cancer' is a collection of disparate diagnoses. There's no question that sun exposure causes Basal cell carcinomas and Squamous cell carcinomas on white people and these are not usually deadly cancers. However, they contribute to a substantial amount of morbidity. Missing ears, eyelids and nose tips are all common excision sites. They may not kill you, but it's nice to avoid them.


But it's melanoma that most people are afraid of, and here he uses the word Melanoma as an oversimplified term, much like using 'Feline' to describe animals ranging from kittens to panthers.


"Melanoma? True, the sun worshipers had a higher incidence of it—but they were eight times less likely to die from it."

These sun worshipers - the "healthy types out getting plenty of exercise and sunlight" in the words of this article - had the kitten. The kitten being the kind of melanoma that arises on the head and neck of chronically sun-damaged white people. It's called lentigo maligna melanoma. These are indolent (slow growing), look like spilled coffee on the skin surface, and are slow to invade. That's why these sun worshipers were less likely to die from their melanoma. The panther version could be on the shoulder of a 30-something white man, deeply invasive and maybe even ulcerated from neglect. That is the kind of melanoma that can kill you.


There are 4 broad categories of melanoma with different molecular aberrations, and different patterns of growth on the skin and under the microscope:

  • sun exposed body parts

  • non sun exposed parts, such as the trunk

  • palms of the hands and soles of the feet

  • mucosal membranes (inside your mouth, vagina, anus and sinuses)


If we put these types into the same basket, the patterns of behavior can't be evaluated accurately. Because the information hasn't been conveyed with any nuance, publications like this article seize on the confusion, and make it seem as if all the medical information and recommendations are wrong.


Almost parenthetically I'll point out that the author seems totally oblivious to why most people wear sun protection - because of the effects on aging! Although variable, this is true for all races. This cause and effect relationship needs no proof beyond what we all see with our own eyes. Wrinkles, discoloration and loss of elasticity are demonstrable changes due to the sun. This is not deadly, but it motivates a lot of the sun protection people wear.


"All early humans evolved outdoors beneath a tropical sun. Like air, water, and food, sunlight was one of our key inputs. Humans also evolved a way to protect our skin from receiving too much radiation—melanin, a natural sunscreen. Our dark-skinned African ancestors produced so much melanin that they never had to worry about the sun.
As humans migrated farther from the tropics and faced months of light shortages each winter, they evolved to produce less melanin when the sun was weak, absorbing all the sun they could possibly get. They also began producing much more of a protein that stores vitamin D for later use. In spring, as the sun strengthened, they’d gradually build up a sun-blocking tan. Sunburn was probably a rarity until modern times, when we began spending most of our time indoors. "


I too like conceiving of much of our public and personal health issues in relation to the last time evolutionary forces acted upon us. Understanding evolution is the best framework to really think big about our health and diseases. Broadly, I think the story he tells here is accurate. Sporadic exposure to damaging sun - manifest in a sunburn - is at the root of many melanomas.


But since I am not living where or how my evolution would dictate, regression to the path demanded by my biology (shaped by evolution) is not the way I want to live. I'm happy about anesthesia, dentistry and surgery (in that order). I'm happy to have enlightenment-based medicine help me personally navigate my genetic predispositions and the effects of society on my biology. I'm white - I'm thankful I to have my moles checked. Medicine, surgery, vaccines don't replace natural things - in general, they improve on them.


In general I say, as that’s not always the case. Modern medicine has made a lot of mistakes in the pursuit of preventing disease and our current post-truth era sows mistrust and doubt in this already fertile ground. Rather than asking why don't people believe us, we physicians should be amazed they still do.


That mistrust lies at the heart of Mr. Jacobsen's article. We in medicine need to find a way to communicate about risk that engenders trust. When we don't communicate about risk (how it is determined and what it means) it creates a vacuum. Into this vacuum come those who seek to profit from illness, from pharmaceutical companies to the modern commodified wellness industry. The author's examples cut to the core of what is wrong with medical communication. His underlying assumption is that we are being epically misled, and although I applaud his skepticism (it's the scientific way), I don't agree with that assumption of malice.


There are many true things contained in the Outdoor magazine article no one is arguing against. Fresh air and sunshine are a cure for a lot of what ails us. Our modern lifestyle is out of step with our mammalian needs. Supplements and products are not effective replacements for what's natural. We all could use less stress, a simple diet of mostly plants, and more time moving our bodies outdoors. I'll happily join him out there. While wearing a wide brimmed hat.

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