For most of us, summer is an easygoing time where we can cast off the burden of winter, dispense with the coats, hats, and boots that clog up the mudroom or front hall, walk barefoot in the grass, and lie in the shade of the trees, meditating on the shapes of the clouds as they pass by. Yet despite what should be a rather pleasant season, for many years we’ve been told that summer harbours something rather sinister and nearly unavoidable. So much so that government health agencies have instituted warnings and policies, with a rush of companies stepping in to help as responsible corporate citizens.Where it was once celebrated not just as a symbol but as the very essence of fertility, it has now become something to be feared and avoided. Is it some new dangerous drug? Has the mayonnaise gone bad? Has someone adulterated our favourite brand of potato chips? No. It’s something far more powerful—something that, as humans, we don’t control.
The sun.
The sun is absolutely essential for all life on earth. It drives photosynthesis, a remarkable biological process that sustains plant life and, by extension, the rest of the food chain. But the sun does more than grow food—it’s vital to our own health and well-being. And yet, increasingly, we’re being told that the sun is dangerous. Of course, most of us understand that getting sunburned is unpleasant and should be avoided. But the idea that the sun is a major health hazard has been amplified to such an extreme that I recently heard a dermatologist on the radio claim there is no “safe level of sun exposure.” Really? Drowning is one of the most frequent causes of accidental death, and yet, does this make water any less crucial to our health and well-being?
While I could comment on the fragmentation of knowledge between scientific disciplines, the more urgent issue is the growing body of evidence that many people—especially those living in temperate zones—may be chronically deficient in vitamin D. We need a certain amount of UVB exposure each day to maintain our circulating vitamin D3 levels. This occurs when UVB converts 7-dehydrocholesterol in the skin into active vitamin D3, which is then further converted by the liver and kidneys into the hormone calcitriol (1). Vitamin D is not just a nutrient; it functions more like a hormone, and is increasingly seen as vital not only for bone health but for metabolic, immune, and cardiovascular function (1). If you struggle with chronic health issues, especially those with an immune or inflammatory component, there’s a good chance you may be deficient in vitamin D. Ask your doctor to test your levels, or work with me, and I can requisition one for you.
In temperate regions of the northern hemisphere, Vitamin D synthesis occurs only during the late spring and summer months, when the sun is at an angle of at least 50 degrees in the sky. You can assess this by placing a stick vertically in the ground—if its shadow is shorter than its height, you’re making vitamin D; if the shadow is longer, you’re not, regardless of how sunny it is. We generally need between 20 and 60 minutes of optimal sun exposure per day to generate adequate vitamin D, depending on skin tone. In cooler latitudes, like most of Canada along the 49th parallel, vitamin D production is limited to roughly mid-April through mid-September. Without adequate sun exposure, vitamin D must come from diet or supplementation. Unfortunately, many fortified foods contain vitamin D2 (ergocalciferol, derived from fungi), which has only a fraction of the biological activity of vitamin D3 (2). Traditional dietary sources of D3 include bone broth, cold-water fish, animal blood, and organ meats like liver—and even though it’s difficult to eat enough to meet our biological needs— the reality is that such foods have in large part disappeared from the modern diet. So where else are we supposed to get it?
The sun?
“But the sun is the scourge of the skies,” caution the dermatologists. “It leads to skin cancer, and that’s a serious disease you want to avoid.” They—and the industries that support them—urge you to remain indoors or, if you must go outside, to slather on a layer of synthetic sunscreen every 20 minutes. These products claim not only to protect your skin from “harmful” UV rays, but also to moisturize and smooth it. So am I against soft, silky skin? Of course not.What concerns me is the broader narrative: that sun exposure is inherently harmful and should be rigorously avoided, especially in light of what we now understand about the importance of vitamin D. Because I prioritize my patients’ health, and am orientated to finding holistic solutions, I’ve taken the time to examine this issue closely.
There are several types of skin cancer, but for simplicity’s sake, most fall into three categories: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Basal cell carcinoma (BCC), which is strongly linked to sun exposure, is almost always non-fatal and rarely metastasizes. It primarily affects individuals with fair skin and tends to have a genetic basis, suggesting that the sun may act more as a catalyst than a root cause. Squamous cell carcinoma (SCC) is also associated with UV exposure, and yet appears with higher frequency in less sun-exposed tissues, including the lungs, esophagus, prostate, and cervix. Like BCC, if it does spread it usually does so locally, not by metastasizing, and is usually not life-threatening.
Malignant melanoma (MM), however, is more complex. While it’s often correlated with sun exposure, the research supporting this thesis is inconsistent at best. For one, the incidence of melanoma has continued to rise even as public awareness and sunscreen usage have increased (3). Outdoor workers have lower rates of melanoma than indoor workers, with research noting that even in patients diagnosed with MM, greater sun exposure was associated with better survival (4). This paradox is explored in a paper by Reichrath and Nürnberg, who describe the “Janus face” of solar UV radiation—the dualistic nature of sunlight that both supports cutaneous vitamin D synthesis and poses risks for skin damage (5). What this means is that the benefits and harms of sunlight are highly context-dependent: determined by dose, skin type, latitude, time of day, and overall health.
UPDATE JULY 21, 2025: The importance of vitamin D3 continues to be underestimated by the medical establishment, something we saw during the pandemic, where health authorities promoting vaccination simultaneously disparaged the benefits of vitamin D3. Interestingly, a new study has demonstrated that low vitamin D levels are strongly associated with increased severity and risk of hospitalization from COVID-19 (6).
There is also emerging evidence that vitamin D synthesized in the skin may have unique immunomodulatory properties distinct from oral supplementation. Unlike oral vitamin D3, which enters the systemic circulation via the digestive tract and liver, cutaneous synthesis initiates localized immune responses in the skin, influencing dendritic cells and keratinocyte activity in a way that may help regulate cytokine balance, including IL-6 (7). This suggests that sunlight is not just important for vitamin D status, but helps to regulate and balance the immune system, which has broad implications not just for cancer prevention but overall health. Why this level of nuance continues to be ignored is hard to say, but undeniably, there are vested interests at play.
Some of the most powerful of these interests are the chemical manufacturers that fund dermatology research and outreach, who ramp up public messaging every summer to sell more sunscreen to an increasingly anxious public. It is increasingly difficult, however, to maintain the narrative that sunscreen ingredients are benign and inert. In 2019 and 2020, randomized clinical trials published in JAMA showed that several common UV filters—including avobenzone, oxybenzone, octocrylene, and ecamsule—are absorbed into the bloodstream at levels that exceed the FDA’s threshold for requiring further toxicological study (8, 9). These findings were observed under normal use conditions, raising valid concerns about systemic exposure to chemical UV filters.
Research has further demonstrated that some sunscreen ingredients are not stable under UV exposure. For example, Gonzalez et al. showed that octyl methoxycinnamate becomes phototoxic in the presence of UV radiation and skin lipids, potentially leading to cellular and DNA damage (10). Fent et al. similarly found that commercial sunscreen formulations undergo photodegradation, forming reactive oxygen species under sunlight (11). These effects raise concerns about the long-term safety of certain chemical sunscreens, particularly in high-UV environments with repeated use. This is separate from the concern of chemical sunscreens polluting the oceans and damaging sensitive ecologies such as coral reefs, which are already under enormous pressure (12). Over the last 25 years I’ve watched the debate around sunscreens intensify, and have consistently advised patients and peers to exercise caution. I often ask my patients: “Since your skin is an absorptive surface, would you feel comfortable spreading sunscreen on your toast?” Either way, it’s going into your body.
There is no doubt in my mind that chemical sunscreens should be avoided unless absolutely necessary, and that we should expose our bodies to the sun for an optimal duration every day to bolster our circulating vitamin D levels and balance immune function. But as I stated at the outset, nobody wants to get burnt – so what do we do?
Well, limiting the times you are out and about when the UV index is highest is the obvious choice. Remember our stick in the ground? If your shadow outside is very short, spend only a little time in the direct sun, and get more active outside during the morning and late afternoon when the temperature is cooler and your shadow is longer. A pale-skinned individual in midsummer probably shouldn’t be lying out at noon. But that same individual, exposed gradually in the morning or late afternoon sun, can get a healthy dose of UVB to synthesize their required vitamin D. Someone that has naturally darker pigmentation, however, will need more time in the sun to meet their physiological requirements.
If you don’t want a tan, make sure to expose your body to the sun for the minimum every day, and then wear clothes made from light, breathable Indian cotton, and a big hat to protect the head, nose, ears and face. If you have to be in the sun because of work, take some precautions by slowly building up a good base tan to darken your skin. To help achieve this, make sure to moisturize your skin with food-grade oils such as coconut and jojoba, or shea and cocoa butter. Applying these fats before and after sun exposure will prevent oxidative damage to the skin, nourishing and protecting it. Fresh aloe gel peeled from the aloe leaf (rather than the minuscule amount in commercial products), and then blended into a paste is a wonderful ally not only to treat burns, it is also an excellent emollient to nourish the skin. And when longer exposure is unavoidable, natural physical sunblocks such as zinc oxide provide broad-spectrum protection without the chemical baggage – just make sure it’s in a natural base, and not carcinogenic petrochemicals.
To protect the body and ensure proper healing from occasional excess sun, everyone should avoid toxins such as alcohol and tobacco, and boost their consumption of free-radical scavenging foods. This includes fresh vegetables and fruits, especially bright colourful foods such as rainbow chard, purple cabbage, kale, lettuce, beets, radishes, tomatoes, blueberries and raspberries, i.e. the VERY food nature provides in abundance during the summer. “You mean the sun grows the very food that protects against its harmful effects?” Yes my friends, life has worked out a rather clever arrangement here on earth, and all we need to do is to discover and align ourselves with its natural intelligence. It is the source of all living things, but in our puny arrogance we seek to malign rather than respect it. But cheer up friends, because an unstoppable new dawn has come for our greatest ally.
The Sun.
References
- Schwalfenberg GK. A review of the critical role of vitamin D in the functioning of the immune system. Mol Nutr Food Res. 2011;55(1):96–108. Link
- Vieth R. Vitamin D supplementation: cholecalciferol, calcifediol, and calcitriol. Eur J Clin Nutr. 2020;74(11):1493–1497. Link
- Garland CF, Garland FC, Gorham ED. Could sunscreens increase melanoma risk? Am J Public Health. 1992;82(4):614–615. Link
- Berwick M, Armstrong BK, Ben-Porat L, et al. Sun exposure and mortality from melanoma. J Natl Cancer Inst. 2005;97(3):195–199. Link
- Reichrath J, Nürnberg B. Cutaneous vitamin D synthesis versus skin cancer development: The Janus faces of solar UV-radiation. Dermatoendocrinol. 2009;1(5):253–261. Link
- Monroy-Iglesias MJ, Forero CG, Álvarez-Álvarez B, et al. Association between vitamin D deficiency and COVID-19 severity and mortality: a systematic review and meta-analysis. PLoS One. 2025;20(5):e0300539. Link
- Segaert S, Simonart T. The epidermal vitamin D system and innate immunity: some more light shed on this unique photoendocrine system? Dermatology. 2008;217(1):7–11. Link
- Matta MK, Zusterzeel R, Pilli NR, et al. Effect of sunscreen application on plasma concentrations of sunscreen active ingredients: a randomized clinical trial. JAMA. 2019;321(21):2082–2091. Link
- Matta MK, Zusterzeel R, Pilli NR, et al. Effect of sunscreen application on plasma concentrations of sunscreen active ingredients under maximal use conditions. JAMA. 2020;323(3):256–267. Link
- Gonzalez H, Farbrot A, Larko O, Wennberg AM. Percutaneous absorption of benzophenone-3 after repeated whole-body applications, with and without ultraviolet irradiation. Chem Res Toxicol. 2006;19(6):733–738. Link
- Fent K, Kunz PY, Zenker A, Rapp M. A tentative environmental risk assessment of the UV-filters 3-(4-methylbenzylidene-camphor), 2-ethyl-hexyl-4-trimethoxycinnamate, benzophenone-3, benzophenone-4 and 3-benzylidene camphor. Mar Environ Res. 2010;69 Suppl:S4–S6. Link
- Downs CA, Kramarsky-Winter E, Segal R, et al. Toxicopathological effects of the sunscreen UV filter, oxybenzone (benzophenone-3), on coral planulae and cultured primary cells and its environmental contamination in Hawaii and the U.S. Virgin Islands. Arch Environ Contam Toxicol. 2016;70(2):265–288. Link
