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A Vegetable a Day May Help Keep Skin Cancer at Bay

Written by Samar Arshad and Edited by Sorina Long

Image by Couleur from Pixabay

Eggs, milk, carrots, spinach—what could all of these different types of food have in common, apart from being the cheapest items you can buy from Whole Foods Market? The answer is simple: they all are vital food sources of vitamin A. Vitamin A, an integral micronutrient, is not created in the body and must be ingested [1]. It is a term that encompasses a large number of related biochemical compounds known as retinoids, which are found in both plant and animal sources [2, 3]. Retinoids are an essential means of keeping our eye, immune, reproductive, and skin health up to par. There is newly found evidence that vitamin A and its class of retinoids can act as chemo-preventative agents to lower the risk of skin cancer—namely, squamous cell carcinoma [3].

Squamous cell carcinoma is a slow-growing skin cancer mainly found in lighter-skinned populations [3, 4]. It is a form of cancer that begins in the thin, fish-scale-like squamous cells found in the tissue that forms the skin’s surface [5]. It occurs most often in areas of the body directly exposed to sunlight, such as the face and head [3]. Though it is usually not life-threatening, it can be aggressive [6]. The treatment of squamous cell carcinoma depends on how far the cancer has progressed and its associated risks [7]. Nonetheless, common treatments include freezing cancer cells and removing them through scalpel treatment, or the simple excision of the cancerous tissue, and radiation as well as chemotherapy therapy to kill cancer cells via X-rays and powerful drugs [7].

But what if squamous cell carcinoma and its subsequent enervating treatment options could be avoided altogether, just by means of consuming more nutrient-dense foods? Such was the thought behind the JAMA Dermatology group study that examined whether vitamin A intake was associated with reduced squamous cell carcinoma risk [3]. This study examined both the vitamin A intake and squamous cell carcinoma risk of over 40,000 U.S. male and female subjects whose data was collected from established NIH studies: the Nurses’ Health Study (1984-2012) and Health Professionals Follow-up Study (1986-2012) [3]. After controlling for health factors such as age and other skin cancers, researchers concluded that a higher intake of total vitamin A, retinol, and individual colored pigments found in fruits and vegetables was associated with a lower risk of squamous cell carcinoma [3]. Compared with 1/5 of the subjects with the lowest vitamin A intake, subjects in the highest 1/5 had a 17% reduced risk for squamous cell cancer [4].

Interestingly enough, the researchers found that vitamin A intake from dietary supplements was not significantly associated with a decreased risk of squamous cell carcinoma; the major source of the reduced risk of squamous cell carcinoma was from vitamin A from food intake [3]. Although dietary supplements can fill nutrient gaps in one’s diet, nutrients are the most potent when straight from food [8]. As one of the senior researchers in the study pointed out, good sources of vitamin A come from cod, eggs, yellow and orange fruits and vegetables, and mainly plant-based food, which in turn can help decrease the risk of other chronic diseases besides skin cancer [4]. Nonetheless, anything in excess can be detrimental to one’s health. As the study pointed out, more research needs to be done to understand the appropriate intake of vitamin A for maximal health benefits, as a high intake of vitamin A may have some adverse health effects [3]. Therefore, one should always keep in mind the risks and benefits associated with vitamin A relative to one’s own physiological capacity.

Overall, it is clear that a diet moderately rich in a variety of sources vitamin A is essential to reaping the micronutrients’ benefits. From better eye, immune, reproductive, and skin health, to a lower risk of cancer, vitamin A and its class of essential retinoids are powerful disease-fighting compounds we all should take note of.

References:

  1. Gilbert C. (2013). What is vitamin A and why do we need it? Community eye health. 26:65. 
  2. “Vitamin A and Skin Health.” Linus Pauling Institute Micronutrient Information Center, Oregon State University, 2 Jan. 2019, https://lpi.oregonstate.edu/mic/health-disease/skin-health/vitamin-A.
  3. Kim, J., Park, M.K., Li, W., Qureshi, A.A., Cho, E. (2019) Association of Vitamin A Intake With Cutaneous Squamous Cell Carcinoma Risk in the United States. JAMA Dermatology. 155:1260–1268.
  4. Bakalar, Nicholas. “Foods High in Vitamin A May Help Ward Off Skin Cancer.” The New York Times, The New York Times Company, 1 Oct. 2019, https://www.nytimes.com/2020/02/01/well/eat/foods-high-in-vitamin-a-may-help-ward-off-skin-cancer.html. 
  5. “NCI Dictionary of Cancer Terms.” National Cancer Institute, National Institute of Health, https://www.cancer.gov/publications/dictionaries/cancer-terms/def/squamous-cell-carcinoma.
  6. Jennings, L., Schmults, C.D. (2010). Management of high-risk cutaneous squamous cell carcinoma. The Journal of clinical and aesthetic dermatology. 3:39–48.
  7. “Squamous cell carcinoma of the skin.” Mayo Clinic, Mayo Foundation for Medical Education and Research (MFMER), 21 June 2019, https://www.mayoclinic.org/diseases-conditions/squamous-cell-carcinoma/diagnosis-treatment/drc-20352486. 
  8. “Should you get your nutrients from food or from supplements?” Harvard Health Publishing, Harvard University, May 2015, https://www.health.harvard.edu/staying-healthy/should-you-get-your-nutrients-from-food-or-from-supplements.

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