Today, we will dig into the truth about cancer and sunshine. We’ve been taught that sunshine is essentially poison, to be avoided at all cost. Billions are made selling sun protection. But is the sun actually good for us?
The sun and cancer connection is weaker than you think
Experts have not yet been able to prove that sun exposure causes skin cancer. A 2020 study analyzed official statistics on cancer mortality and incidence. They then compared the data with certain geographic regions, and more specifically to climate zones. A climate zone in this study is “a variable that combines moisture level and temperature in a given area” [7].
Comparing 15 states in the US, they found that the east coast had a higher rate of cancer-related deaths and incidence. This is consistent with data from the past that shows the east coast has significantly higher rates of cancer than the rest. The Midwest follows closely behind. These higher rates of cancer include skin melanoma and other forms of skin cancer. These areas are often darker and have LESS sunlight.
What do statistics tell us about the weather-cancer connection?
According to the CDC’s state-level cancer profiles, some sunnier states have a lower incidence of skin cancer than other ‘colder” states. New Mexico, Texas, Puerto Rico and Texas are among the five states that have a lower incidence of cancerous melanoma. Based on information over the past 5 years, Puerto Rico has a lower melanoma rate than Texas, Texas, and New Mexico. Texas has 13 cases per 100,000 people [2].
Utah, New Hampshire, Vermont and Minnesota are the top four states on the list. These states have more than 30 cases per 100,000 residents, while Utah has over 40 diagnoses per 100,000 [2]. This is actually 10 times more skin-cancer diagnosis than Puerto Rico.
Cancer goes with bad weather?
Researchers found that higher precipitation was associated with an increased risk of all types and types of cancer in the above study [7]. This is in line with the CDC statistics that show a higher incidence of cancer on the east coast.
This doesn’t necessarily mean that cold weather will increase your cancer risk or that warm, dry weather will protect you from it. The study actually showed that lung cancer rates were higher in warmer regions. However, these findings only covered 15 states. This conclusion might not be true if you look at the entire country.
The study’s findings need to be investigated further. Researchers have a few theories to explain the link between rain and cancer incidence. They mainly base their theories on the effects of continual precipitation in the environment. On the east coast, soil is deficient in magnesium and potassium, which makes it more acidic. In some cases, this can lead to the release of nitrous acid into our atmosphere. According to health authorities, the carcinogenic compound nitrous acid [10] is being considered by many. Vitamin D deficiency could also be a reason, which ironically is more common in populations that live in warmer climates.
Sunshine may actually PREVENT more cancer than it causes
Vitamin D deficiency is one theory that could explain the higher incidence of cancer on the east coast. Vitamin D is actually a group fat-soluble compounds your body can convert into hormones. Vitamin D can have important functional effects that ensure your body functions properly. Doctors and researchers had believed that vitamin D’s primary function was to strengthen bones and calcium, and help with phosphorous and calcium metabolism. Recent research suggests that vitamin D may also help lower your risk of developing cancer.
Accordingly, the incidence of cancer in southern latitudes has been shown to be statistically lower than that in northern latitudes. These stats could be due to increased sunlight exposure, which allows for vitamin D production.
Other studies showed that mice with tumors grew slower when they were given adequate vitamin d, as opposed to mice who had low levels. The national cancer institute says that vitamin d is still under investigation, but preliminary evidence has shown it to have an influence on cell growth, cell death, and tumor growth. This could potentially influence the progression of cancer [8].
Despite these promising results, there’s no solid evidence that vitamin d can reduce cancer risk. It is possible that higher levels of vitamin d in blood could be correlated with other healthy behaviors like exercising outside. This could increase the risk of developing cancer.
Although vitamin d was found to be associated with a statistically lower incidence of colorectal cancer [8], the results are still unclear. Researchers have not been able to link vitamin d with other types of cancer.
Experts know that vitamin d deficiencies, while rare, can have serious consequences for your health and increase your risk of developing cancer. You can prevent it by getting checked for vitamin D blood levels and asking your doctor about supplementation.
Breast cancer and UV light
Research on the connection between sun exposure and breast cancer remains inconclusive, but it is still suggestive. A 2020 meta-analysis paper found that there is a link between sun exposure and LOWER breast cancer risk. The link was stronger for women older than 40 [9]. The study did not find that sunscreen usage affected this relationship. You could still benefit from sunlight by using sunscreen [9].
However, these results are based only on statistics and have not been tested with animals or people. The studies did not consider other risk factors like lifestyle changes, ethnic factors and occupational exposure to carcinogenic chemicals.
Final thoughts
As with all aspects of your life, exposure to sunlight can have an impact on your risk of developing cancer. Researchers are still unsure how sunlight interacts with the body. We do know that too much or too few sunlight can have adverse effects on your health, and increase your risk of developing cancer.
It is important to remember that the sun’s harsh effects can be avoided by following general protection guidelines. Sunscreen is recommended and you should avoid the midday sun. You should also ensure that your vitamin D levels are stable by getting out in the morning sun and supplementing as recommended by your doctor.
But if you’d like to enjoy the sunshine WITHOUT using sunscreen, try this.
References
American Cancer Society. Skin cancer. Available here.
State Cancer Profiles, National Cancer Institute. Incidence rates table, report by state, melanoma of the skin, 2013-2017, all races. Available here.
Skin Cancer Foundation. Skin cancer 101. Available here.
World Health Organization. Cancer fact sheet. Available here.
American Association for Cancer Research. Air pollution might be associated with many kinds of cancer. Available here.
Skin cancer foundation blog. After a transplant, new dangers. Available here.
Vishal Shah, et al. Environmental Engineering Science. Dec 2019. 1452-1458. Available here.
National Cancer Institute. Vitamin D and cancer prevention. Available here.
Li, Yilun et al. Exposure to solar ultraviolet radiation and breast cancer risk, Medicine: November 06, 2020 – Volume 99 – Issue 45 – p e23105. Available here.
Science direct. Nitrosamine – an overview. Available here.