Vitamin D was first identified in 1932 by Askew with the isolation of Vitamin D1 (an artefact of Vitamin D2), and then in 1935, 7-dehydrocholesterol, pre-cursor to Vitamin D3 was identified by Windaus and Bock, and then finally in 1937, Vitamin D3 was discovered followed by the identification of pre-vitamin D3 in the skin by Dr MF Holick in 1977 (Deluca, 2014). Yet, the importance of Vitamin D was known since 1650 due to rickets disease (Wolf, 2004).
Vitamin D deficiency is a chronic issue for all people, as we live indoors. Generation of Vitamin D is controlled by multiple factors such as UVB availability, skin colour, age, latitude and altitude. “Vitamin D provides an innate immune response to pathogen threat” (White, 2018).
So, what does a Japanese look like after living naked for 29 years on a deserted island at the 24th latitude? He has a dark tan from the increased melanin production that brings him to equilibrium with the environment. For a person beyond 80 years of age, you will notice that his mental acuity, body flexibility, eye sight and his calmness is far superior than the usual city dweller of equivalent age or younger. My own grandmother of 88 years shows similarity to this, despite living a bit higher latitude than the castaway, but spends the majority of her time outdoors tending to her multiple seasonal gardens.
Vitamin D is also known to regulate the hormone, renin, which controls blood pressure, while also controlling the vascular smooth muscle to relax in the presence of 25OHD (Persson, 2003; Mead, 2008). In a 2004 study, researchers found a correlation where hypertension (high blood pressure) was more prevalent in winter than summer (Charach, Rabinovich and Weintraub, 2004). This would correlate well with the fact that there is less opportunity for UVB radiation during winter when in the higher latitudes beyond 35 degrees.
Vitamin D is a hormone that is well known for its use in calcium absorption and bone health, yet there are health issues that have been recorded where Vitamin D deficiency has been associated with obesity, depression, Rickets disease and Seasonally Affected Disorder (SAD).
Vitamin D deficiencies may indicate associations to the pathogenesis of disease such as cardiovascular disease and autoimmune thyroid diseases such as Graves and Hashimoto disease (Kivity et al., 2011; White, 2018).
There are strong associations of a high incidence and mortality of breast cancer when Vitamin D is deficient (Garland et al., 2007). The Sunlight, Nutrition, and Health Research Centre has also correlated similar associations of mortality to breast cancer, ovarian and colon cancer to higher latitude cities across the United States (Grant, 2018).
Vitamin D insufficiency is also one of three (3) environmental risk factors for multiple sclerosis (Pierrot-Deseilligny and Souberbielle, 2013).
Prevalence of disease to higher latitudes is a strong indicator to assume that the lack of UVB light to generate Vitamin D3 naturally in the skin can be a major factor influencing optimal health. Below are some of the research that seems to indicate such effects:
• there were less incidences of childhood type1 diabetes when closer to the equator. (Mohr et al., 2008)
• There is a strong correlation of Crohn’s disease and ulcerative colitis in higher latitudes (away from the equator) where UV availability is lower than the equator (Szilagyi et al., 2014)
• Higher latitudes are associated with a higher prevalence of Kawasaki disease (Chang et al., 2018)
• Higher prevalence of schizophrenia in higher latitudes and colder climates (Kinney et al., 2009).
• Multiple sclerosis disease onset is highly significant at higher latitudes (Simpson et al., 2011; Tao et al., 2016).
• In locations of high UVB availability, colorectal cancer was less prevalent (Cuomo et al., 2013)
• There is a 5 times higher risk of breast cancer for those with lower serum levels of Vitamin D3 (Garland et al., 2006).
• Lower risk of prostate cancer for those that had a high level of sun exposure (Garland et al., 2006).
• There is an increased incidence of leukemia in low UVB locations (Mohr et al., 2011).
However, with above such research, there are so many other variables such as the population study size, amount of time spent outdoors, season, clothing, time of day, skin colour, sunscreen use and serum Vitamin D levels can all contribute to the results. It is highly recommended to review the graphs from the studies by Mohr & Garland as there are very clear trends in disease prevalence based on latitude/UVB availability. The Vitamin D receptor (VDR) is the only receptor that is found in all cells except the mitochondrial membrane. The VDR is thought to play a critical regulatory function on all cellular growth in both normal and cancerous cells (Holick, 2004). Vitamin D is a very effective immune regulator and the activated T and B lymphocytes also have VDRs (Holick, 2004).
Theory: inflammatory bowel disease, such as Crohn’s disease are associated with vitamin D deficiency (Ham et al., 2014; White, 2018), and given recent publications on how seasonal variation plays a role in the gut microbiome (Schnorr et al., 2014; Smits et al., 2017), could Crohn’s disease and any other inflammatory bowel disease be a disease of light and/or diet? Current research have specific challenges in correlating “cause and effect” due to the diversity of microbial profiles, yet having a balanced diet in fruit and vegetables, with reductions in processed foods and meats may reduce or alleviate the inflammation (Lane, Zisman and Suskind, 2017; Rapozo, Bernardazzi and de Souza, 2017). As discussed in earlier sections where circadian rhythms influences and control metabolism and the lack of sun light affects Vitamin D synthesis, would a less diverse food (unprocessed) or consuming foods that are out of season lead to a less diverse gut microbiome? Should we really be eating coconut, honey and bananas in the middle of Winter in Melbourne, Australia? Are we eating in equilibrium with our environment?
According to Jeff Leach (microbiome researcher who spent several years with the Hadza), the gut flora can be changed quickly in 24-72 hours (Rutscher, 2018). Other research also confirms this statement, where flora or fauna diets will rapidly change the microbial diversity (David et al., 2014). Jeff Leach found that seasonal diets of the Hadza influenced the microbiota and there were rare microbiome species that appeared and disappeared with different seasons, yet these rare species are non-existent in industrialized societies (Smits et al., 2017). Can our modern transportation technologies, shipping food from different states or countries be reducing our microbial diversity? The Hadza also had one of the more broadest range of gut flora than any other society (pre-industrialized and industrialized) (Smits et al., 2017). Jeff is currently part of a group of researchers doing ‘citizen science’ research collecting gut microbial samples across the world as a cohort study for the American Gut Project and brings together a collective view of microbial diversity (McDonald et al., 2018). Would we see a similarity of microbial diversity for industrialized societies that are directly correlated to imported foods?