Light exposure for the gut, by Marc Sorenson, EdD L
Light exposure for the gut seems like a strange concept. And, rest assured we will not discuss shining light directly into the gut to optimize health. However, light exposure, according to new research, may assist in gut homeostasis and may positively alter the gut microbiome.
Some words you should know to better understand light exposure for the gut:
Circadian rhythms: Circadian rhythms are variations in physiology and behavior persisting with a cycle length close to, but not exactly, 24 hours. It is necessary to synchronize the rhythms on a regular basis to maintain them. And, such synchronization is usually achieved through regular exposure to light and darkness.
Entrainment: Entrainment occurs when rhythmic physiological or behavioral events are matched to an external environmental factor. So it is ultimately the interaction between circadian rhythms and the environment, especially sunlight or darkness.
Homeostasis: The maintenance of metabolic equilibrium and balance within an animal by a tendency to compensate for disrupting changes. Thus, homeostasis is vital for good health. And conversely, a lack of homeostasis in the gut is a disease state.
Microbiome, or microbiota: A collection of microorganisms living in or on the human body. For the purposes of this discussion, we are interested in those microorganisms, such as bacteria, inhabiting the gut.
UVB: Ultraviolet B light, a part of the solar spectrum, which is also used in experiments by way of sun lamps.
Circadian rhythms: Circadian rhythms are variations in physiology and behavior persisting with a cycle length close to, but not exactly, 24 hours. It is necessary to synchronize the rhythms on a regular basis to maintain them. And, such synchronization is usually achieved through regular exposure to light and darkness.
Entrainment: Entrainment occurs when rhythmic physiological or behavioral events are matched to an external environmental factor. So it is ultimately the interaction between circadian rhythms and the environment, especially sunlight or darkness.
Homeostasis: The maintenance of metabolic equilibrium and balance within an animal by a tendency to compensate for disrupting changes. Thus, homeostasis is vital for good health. And conversely, a lack of homeostasis in the gut is a disease state.
Microbiome, or microbiota: A collection of microorganisms living in or on the human body. For the purposes of this discussion, we are interested in those microorganisms, such as bacteria, inhabiting the gut.
UVB: Ultraviolet B light, a part of the solar spectrum, which is also used in experiments by way of sun lamps.
First of all, let’s discuss the effect of light exposure on gut homeostasis.
There are specialized cells in the body called ILC3s, which are major regulators of inflammation, infection, microbiota composition and metabolism in the gut.
These cells do not function well if they are not synchronized to the biological clock (or circadian rhythm). So, the most effective way to assure that these cells are working is through external light exposure, particularly sunlight. Light signals are the major entraining cues of ILC3s.
In fact, as a result of the removal of circadian regulators in intestines, the researchers showed that many problems occur. Without regulators, light exposure can’t do its job, and therefore the circadian rhythms of the gut would be extinguished. Why? Because ILC3s could not connect to those regulators in the gut. Thus, this caused disrupted homeostasis, impaired epithelium, a deregulated microbiome, increased infection and disrupted lipid metabolism. The researchers stated that “Our work reveals a circadian circuitry that translates environmental light cues into enteric [intestinal] ILC3s, shaping intestinal health, metabolism and organismal homeostasis.” So the bottom line is, for gut health, get your sun exposure daily!
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Secondly, another investigation provides more information regarding light exposure and the gut microbiome.
Light exposure, vitamin D and microbiome makeup are all associated with inflammatory conditions like multiple sclerosis and inflammatory bowel disease. Therefore, scientists hypothesized that a causal chain links the three. So to test the hypothesis, they used female volunteers in a scientific experiment. In addition to three one-minute sessions of full-body UVB exposures, the volunteers had their blood vitamin D levels tested. Furthermore, before and after treatment, stool samples were taken for analysis of volunteers’ gut microbiomes.
The results regarding UVB light exposure and gut microbiome.
As a result of this minuscule UVB light exposure, good bacteria increased in the microbiome, as did vitamin D. Another fact mentioned in the paper was that studies in rodents indicated UVB increased good bacteria while decreasing harmful bacteria. So does this prove vitamin D could be responsible for lessening risk of multiple sclerosis (MS) and inflammatory bowel disease? No. It is especially relevant that many studies on vitamin D supplementation and MS show no effect. The one consistent outcome of the studies is that sun exposure always lessens the risk of MS. Sun exposure produces the marvelous hormone, vitamin D, but it also produces serotonin, endorphin, nitric oxide, BDNF and dopamine. In addition, there are many more photoproducts produced by sun exposure, which have not been fully studied for health benefits.
When possible, use sun exposure or other UVB light exposure to produce your vitamin D.
Therefore, vitamin D levels are, in many cases, surrogate measurements for sun exposure. The health benefits attributed to vitamin D may be due to other factors also being produced by sun exposure. The sun should be used holistically when possible. Using only one photoproduct of sun exposure seems like a mistake. Thus, it is much like extracting a single plant vitamin. That vitamin doesn’t have the health benefits of the entire plant, because it lacks fiber and other nutrients. Therefore, the closest thing to holistic sun is the use of a sunlamp or a sunbed. For more information, visit the sunlight Institute website.
In conclusion, take care of your gut and your health through non-burning, regular sun exposure.
For more information on sun exposure and MS, read the book, Embrace the Sun. Read more on circadian rhythms on http://sunlightinstitute.org/
Marc Sorenson, EdD
What is IBD?
First of all, IBD consists of two primary diseases, ulcerative colitis (UC) 
and Crohn’s disease (CD). UC is a chronic inflammatory condition characterized by relapsing and remitting episodes of inflammation limited to the mucosal layer of the colon.[1] Crohn’s disease, however, can involve any part of the gastrointestinal tract from the mouth to the anus. Yet, it most commonly affects the small intestine or the colon, or both.[2]
The gift of sunlight
First of all, there is a beautiful gift that may prevent or lessen IBD. The gift, (sunlight) awaits us, but if we do not accept the gift, we are no better off than if we didn’t have it. So it is in Italy, where those who suffer from IBD are shown to have far less sun exposure than those who do not have the disease.[3] Therefore, this may indicate that part of the cause of IBD is lack of sunlight. And in Italy, low sun exposure probably indicates a reluctance to step outside because, Italy is a sunny country. Maybe, many of the Italians who succumb to IBD, have obviously not accepted the gift. Either that, or they are using too much sunscreen, since sunscreen blocks the sun.
Furthermore, IBD patients are at an increased risk for fractures. Hence, one may conclude that both maladies may be due to low sun exposure.
Embrace the sun to prevent IBD
Another investigation, conducted over 12 years and involving hundreds of thousands of IBD patients produced remarkable outcomes. Hospitalizations for both UC and CD were far higher among those with low sun exposure.[4] And, the same relationship was shown between sun exposure, bowel surgeries and deaths: more surgeries were needed for those patients who experienced the lowest sun exposure. Also, more deaths occurred among those with low exposure.
And what about non-IBD patients?
Another side note to this investigation was the large number of non-IBD patients analyzed for sun exposure levels. It is most noteworthy that the same relationship existed as with the IBD patients. Low sun exposure associated with prolonged hospitalizations and more deaths when compared with high exposure. Especially relevant is other research involving the association of Crohn’s disease to surgery. It found that surgery for the disease was significantly reduced among patients who received more sun exposure.[5]
The north-south gradient
In addition, research shows that in the US, there is a north-south gradient for IBD risk.[6], [7], [8], [9] The risk of developing the disease is significantly lower in southern latitudes (because sun exposure is greater).
An important nutritional note about IBD:
In addition to what we have heretofore described, it is especially relevant to understand that IBD causes malabsorption of nutrients in the gut. Consequently, it leads to diseases of malnutrition.[10] And, vitamin D is one of the “nutrients” that may not be absorbed efficiently. Therefore, sun exposure (or sunlamps) may be the only viable source of vitamin D for a person with IBD.
Most of all, remember that non-burning sun exposure is essential to human health. It seems like a good idea to obtain your share, and protect your gut from IBD.
[1] Peppercorn M, Cheifetz, A, Rutgeerts P, Grover S. Definition, epidemiology, and risk factors in inflammatory bowel disease. http://www.uptodate.com/contents/definition-epidemiology-and-risk-factors-in-inflammatory-bowel-disease.
[2] Web MD http://www.webmd.com/ibd-crohns-disease/crohns-disease/inflammatory-bowel-syndrome.
[3] Vernia P, Burrelli Scotti G, Dei Giudici A, Chiappini A, Cannizzaro S, Afferri MT, de Carolis A. Inadequate sunlight exposure in patients with inflammatory bowel disease. J Dig Dis. 2018 Jan;19(1):8-14
[4] Limketkai BN, Bayless TM, Brant SR, Hutfless SM. Lower regional and temporal ultraviolet exposure is associated with increased rates and severity of inflammatory bowel disease hospitalization. Aliment Pharmacol Ther. 2014 Sep;40(5):508-17.
[5] Govani SM, Higgins PD, Stidham RW, Montain SJ, Waljee AK. Increased ultraviolet light exposure is associated with reduced risk of inpatient surgery among patients with Crohn’s disease. J Crohns Colitis. 2015 ;9(1):77-81
[6] Schultz M, Butt AG. Is the north to south gradient in inflammatory bowel disease a global phenomenon? Expert Rev Gastroenterol Hepatol. 2012 Aug;6(4):445-7.
[7] Kappelman MD, Rifas-Shiman SL, Kleinman K, Ollendorf D, Bousvaros A, Grand RJ, Finkelstein JA. The prevalence and geographic distribution of Crohn’s disease and ulcerative colitis in the United States. Clin Gastroenterol Hepatol. 2007 Dec;5(12):1424-9.
[8] Sonnenberg A. Similar geographic variations of mortality and hospitalization associated with IBD and Clostridium difficile colitis. Inflamm Bowel Dis. 2010 Mar;16(3):487-93.
[9] Holmes EA, Xiang F, Lucas RM. Variation in incidence of pediatric Crohn’s disease in relation to latitude and ambient ultraviolet radiation: a systematic review and analysis. Inflamm Bowel Dis. 2015 ;21(4):809-17
[10] Margulies SL, Kurian D, Elliott MS, Han Z. Vitamin D deficiency in patients with intestinal malabsorption syndromes–think in and outside the gut. J Dig Dis. 2015 Nov;16(11):617-33.
First of all, let’s define IBD:
Inflammatory bowel diseases (IBD) are known as Crohn’s disease (CD) and Ulcerative Colitis (UC). UC is a chronic inflammatory condition characterized by relapsing and remitting episodes of inflammation limited to the mucosal layer of the colon.[1] Crohn’s however, can involve any part of the gastrointestinal tract from the mouth to the anus, but most commonly affects the small intestine or the colon, or both.[2]
New Italian Research
Research from Italy, published in December, 2017, shows that inadequate sun exposure is associated closely with IBD.[3] The researchers demonstrated that “Patients with IBD are significantly less exposed to sunlight then controls in our Mediterranean Country, often to an extent that may impair Vitamin D activation.” Consequently, they suggest that increased sun exposure may prove beneficial to patients.
Other research:
Furthermore, in a 12-year investigation of hundreds of thousands of IBD patients, the following was found: Hospitalizations and prolonged hospitalizations for both UC and CD were higher among those who had low sun exposure, compared to those with very high sun exposure.[4] In addition, the same relationship was shown between sun exposure, bowel surgeries and deaths: more surgeries were needed for those IBD patients who experienced the lowest sun exposure compared to those who had the highest sun exposure, and more deaths occurred among those with low exposure.
Does sun exposure help other diseases?
Furthermore, an interesting side note to the aforementioned investigation was the large number of non-IBD patients analyzed for sun exposure levels. Most noteworthy was the finding that the same relationship existed as with the IBD patients—low sun exposure was associated with prolonged hospitalizations and more deaths when compared with high exposure. Therefore, sun exposure saves lives, whether by decreasing IBD or preventing the myriad additional diseases that we have previously discussed.
In conclusion, if you have a painful feeling deep in your gut, take action: First of all, get a diagnosis. But do it while simultaneously increasing your safe, non-burning sun exposure. It may be just what the doctor ordered!
[1] Peppercorn M, Cheifetz, A, Rutgeerts P, Grover S. Definition, epidemiology, and risk factors in inflammatory bowel disease. http://www.uptodate.com/contents/definition-epidemiology-and-risk-factors-in-inflammatory-bowel-disease.
[2] Web MD http://www.webmd.com/ibd-crohns-disease/crohns-disease/inflammatory-bowel-syndrome.
[3] Vernia P, Burrelli Scotti G, Dei Giudici A, Chiappini A, Cannizzaro S, Afferri MT, de Carolis A. Inadequate Sunlight Exposure in Patients with Inflammatory Bowel Disease. J Dig Dis. 2017 Dec 18. doi: 10.1111/1751-2980.12567. [Epub ahead of print]
[4] Limketkai BN, Bayless TM, Brant SR, Hutfless SM. Lower regional and temporal ultraviolet exposure is associated with increased rates and severity of inflammatory bowel disease hospitalization. Aliment Pharmacol Ther. 2014 Sep;40(5):508-17.
Marc Sorenson, EdD
IBD consists of two primary diseases, ulcerative colitis (UC) and Crohn’s disease (CD). UC is a chronic inflammatory condition characterized by relapsing and remitting episodes of inflammation limited to the mucosal layer of the colon. [1] Crohn’s however, can involve any part of the gastrointestinal tract from the mouth to the anus but most commonly affects the small intestine or the colon or both.[2] The most common symptoms of IBD are abdominal pain, weight loss, fever, rectal bleeding, skin and eye irritations and diarrhea.
In a 12-year year investigation of hundreds of thousands of IBD patients, measuring both UC and CD, hospitalizations and prolonged hospitalizations for both diseases were higher among those who had low sunlight exposure compared to those with very high sunlight exposure.[3] The same relationship was shown between sunlight, bowel surgeries and deaths; more surgeries were needed for those patients who experienced the lowest sunlight exposure compared to those who had the highest sunlight exposure, and more deaths occurred among those with low exposure.
An interesting side note to this investigation was that a large number of non-IBD patients were also analyzed for sunlight exposure amounts. As with the IBD patients, low sunlight exposure was associated with prolonged hospitalizations and more deaths when compared with high exposure.
French research has shown that high residential sun exposure is associated with a low risk of CD,[4] but not UC. Women who were in the highest third of sunlight exposure had only half the risk of CD compared to those in the lowest third, but UC was increased 21% by high sunlight exposure. This study was the only one I have seen—other than studies on non-melanoma skin cancer—that indicated a positive association of sunlight exposure with disease risk. None of the other studies mentioned here showed that relationship with UC. Another interesting side note to this research was that vitamin D intake was not associated with decreased risk of CD.
It has also been shown that in both Europe and the US, there is a north-south gradient for IBD,[5] meaning that the risk of developing IBD is significantly lower for the southern latitudes (where sunlight exposure is greater). And finally, another French study has demonstrated that low sunlight exposure is associated with an increased incidence of Crohn’s disease.[6]
So for a healthy gut, sunlight exposure plays a vital role.
[1] Mark A Peppercorn, Adam S Cheifetz, Paul Rutgeerts, Shilpa Grover. Definition, epidemiology, and risk factors in inflammatory bowel disease. Uptodate http://www.uptodate.com/contents/definition-epidemiology-and-risk-factors-in-inflammatory-bowel-disease. Accessed July 1, 2015.
[2] Web MD http://www.webmd.com/ibd-crohns-disease/crohns-disease/inflammatory-bowel-syndrome. Accessed July 1, 2015.
[3] Limketkai BN1, Bayless TM, Brant SR, Hutfless SM. Lower regional and temporal ultraviolet exposure is associated with increased rates and severity of inflammatory bowel disease hospitalization. Aliment Pharmacol Ther. 2014 Sep;40(5):508-17.
[4] Jantchou P1, Clavel-Chapelon F, Racine A, Kvaskoff M, Carbonnel F, Boutron-Ruault MC. High residential sun exposure is associated with a low risk of incident Crohn’s disease in the prospective E3N cohort. Inflamm Bowel Dis. 2014 Jan;20(1):75-81.
[5] Schultz M1, Butt AG. Is the north to south gradient in inflammatory bowel disease a global phenomenon? Expert Rev Gastroenterol Hepatol. 2012 Aug;6(4):445-7.
[6] Nerich V1, Jantchou P, Boutron-Ruault MC, Monnet E, Weill A, Vanbockstael V, Auleley GR, Balaire C, Dubost P, Rican S, Allemand H, Carbonnel F. Low exposure to sunlight is a risk factor for Crohn’s disease. Aliment Pharmacol Ther. 2011 Apr;33(8):940-5.