Let Some Sunshine into Your Anticancer Strategy

Sunlight is a force that can heal or hurt the body. Media attention on sun exposure focuses on two topics on each side of that polarity: either the benefits of vitamin D synthesis from sun exposure or skin cancer from ultraviolet radiation. There is a significant amount of nuance between those poles that will help clarify your optimal relationship with the sun.

Does Excessive Sun Exposure Cause Skin Cancer?

With sunburn, undoubtedly the answer to that question is yes. Ultraviolet radiation in the form of a sunburn damages skin cells, drives mutation, and has been shown to increase the risk of melanoma, both basal cell carcinoma and squamous cell carcinoma. By that virtue, it is possible to lower one’s risk of skin cancer by never venturing out into the sun. Here’s the problem: Doing so increases your risk of many other cancers.

Hormesis is all about getting the dosage right. Too little sun exposure is just as harmful as too much. The association between sunshine and reduced cancer risk has been known for decades, but chances are you haven’t heard that from the fear factory of mainstream media. Research suggests that sunlight causes human skin cells to synthesize vitamin D. This may be the main factor underlying the inverse relationship between sunlight exposure and the risk for colorectal, breast, and prostate cancer as well as non-Hodgkin’s lymphoma. Even with melanoma, it is only intense sun exposure, as from a sunburn, that is associated with increased risk. Regular low-level sun exposure does not appear to increase melanoma rates. What does increase melanoma risk is commercially available sunblock.

The Scandal of Sunblock

Sunscreen can be as much a strategy as a topical: staying out of the midday sun, wearing clothing to protect skin, or seeking shade. Sunblock is a substance applied to the skin that allows for a period of full-sun skin exposure. If you’re just soaking up 20 to 30 minutes of off-peak sun exposure, you can choose to use sunscreen options for the rest of your time outdoors. When cover isn’t an option, then some form of sunblock is necessary. However, the devil is in the details, particularly in relation to cancer risk.

Commercial sunblocks contain a cocktail of unsavory chemicals that absorb through the skin and add to the body’s total burden of toxicant exposure. Sometimes, they are directly carcinogenic. The common sunblock ingredients oxybenzone, homosalate and avobenzone are endocrine disruptors. The chemical octocrylene that is found in some sunblocks degrades over time to form benzophenone, and many sunblocks contain benzene. Both are overt carcinogens. It is unfathomable to me that it is standard procedure to avoid sunburn to reduce cancer risk by applying a bunch of chemicals that contribute to cancer formation on one’s porous skin. Suffice it to say, you should not use chemical sunblock.

Natural sunblocks such as coconut oil can be applied to the skin to achieve a modest SPF of 8, and that might be enough for a limited time in the sun. But for a higher degree of protection, the most potent natural sunblock is carrot seed oil, thought to have an SPF around 40. Small amounts of carrot seed oil can be mixed with coconut oil as a carrier for use as an effective natural sunblock.

Sunbathing to Prevent Cancer

Safe sun exposure is an anticancer strategy. One likely mechanism is vitamin D synthesis. In vitro studies show an inhibition of cell proliferation and regulation of apoptosis (intentional, programmed cell death) for many cancer subtypes. Other ultraviolet-induced mediators besides vitamin D may also contribute to an anticancer effect. Morning and midday sun exposure helps maintain a healthy circadian rhythm, the disruption of which has been linked to several malignancies, notably breast cancer. Daylight also encourages nighttime release of melatonin, a potent antioxidant with significant anticancer benefits. 

Collectively, these mechanisms—and others yet to be discovered—highlight the simple truth that nature heals if we obey natural law.