Studies regarding skin color, vitamin D, and racial health disparities:
Abstract C046: Dietary Calcium and Vitamin D and Sun Exposure with the Risk of Breast Cancer Among African American Women (2020)
Conclusion: Due to the vitamin D synthesis-blocking effects of skin melanin, dark-skinned people tend to suffer both higher rates of vitamin D deficiency and vitamin D deficiency diseases, including cancer. This study evaluated and compared the dietary and supplementary intake of vitamin D and sun exposure habits of 1033 black women with breast cancer and 391 healthy black women without breast cancer – all in New Jersey. Researchers found that the women who took vitamin D supplements enjoyed a “significant decreased overall” breast cancer risk. Researchers also found that “more daylight hours spent outdoors in a year predicted a lower risk of pre- and postmenopausal BrCa [breast cancer]”
Intake of Vitamin D and Calcium, Sun exposure, and Risk of Breast Cancer Subtypes Among Black Women (2019)
Conclusion: To investigate associations between vitamin D, sun exposure, and risk of breast cancer in black women, researchers evaluated 1724 black female breast cancer patients and 1233 healthy matched controls for their reported total amount of daylight hours spent outside (in the sun). What they found is that those who spent the most time outside had the lowest risk of breast cancer, for all types of breast cancer, compared to the women who reported the least time spent outside. It’s also important to mention that blacks, due to the vitamin D production-blocking effects of melanin, tend to suffer much higher rates of vitamin D deficiency and black women are nearly twice as likely to develop the more aggressive types of breast cancer.
Conclusion: This article gives an overview of how, for the at least the last 20 years, black people in America have had higher blood pressure compared to white people. People with darker skin make less vitamin D from sun exposure and vitamin D-deficiency has been strongly associated with high blood pressure.
Excerpt: “Autism incidence has also been linked to maternal vitamin D insufficiency in dark-skinned mothers living in northern latitudes. Reports have correlated low concentrations of maternal 25(OH)D3 with increased risk of having a child with behavioral problems associated with autism, such as language impairment and attention-switching difficulties. In addition, Somali mothers who moved to Stockholm have been shown to be severely vitamin D deficient (<20 ng/ml) and have approximately a 4.5 times higher risk of having a child with autism, as compared with native Swedes. This is in contrast to African individuals living in East Africa, who have mean 25(OH)D3 concentrations of 48 ng/ml. Autism incidence in the Somali population living in Minneapolis also appears to be high. In 2008, the Minneapolis school district enrolled 0.94% of Somali children, 0.52% of non-Somali African American children, 0.38% of Hispanic children, and 0.20% of Caucasian children in their citywide ASD preschool program.”
Serum Vitamin D Profile In Black African Men with Prostate Cancer at Tertiary Referral Facility in Sub-Saharan Africa (2014)
Conclusion: The vitamin D blood levels of 162 black African prostate cancer patients were analyzed. 88.9% of them were vitamin D-deficient. This is in accordance with many other studies that have found black men to suffer much higher rates of vitamin D-deficiency.
Conclusion: This study of 7,540 autistic children in Los Angeles County, California found that children born from foreign-born black mothers, children born from foreign-born Central/South American mothers, children born from foreign-born Filipino mothers, children born from foreign-born Vietnamese mothers, and children born from U.S.-born Hispanic and black mothers – all demographics with darker skin – have an increased risk for severe autism compared to children from U.S.-born white mothers. Could this be because of the well-documented fact that darker-skinned people are much more likely to suffer from vitamin D-deficiency?
25-Hydroxyvitamin D in African-Origin Populations At Varying Latitudes Challenges the Construct of a Physiologic Norm (2014)
Conclusion: The vitamin D levels of 2500 black adults from Chicago, Jamaica, Ghana, South Africa, and Seychelles (500 subjects from each territory) were measured. Those living closer to the equator had higher vitamin D levels compared to those farther away from the equator. Chicago subjects, farthest away from the equator, had the highest rate of deficiency.
UV Radiation and the Skin (2013)
Note: This article covering the relationship between human skin and UV provides a detailed explanation of the differences between racial skin types and how this affects response to sunlight.
Conclusion: This study of 3,918 autistic children in Sweden found that children born from Sub-Saharan African migrants, children born from North African migrants, children born from Latin American migrants, children born from Caribbean migrants, and children born from southern Asian migrants all had an increased risk for developing low-functioning autism. Could this be because they are all dark skinned people from extremely sunny areas moving to a country that gets very little sunshine in comparison, putting them and their offspring at an extreme risk of developing vitamin D-deficiency – which could be playing the primary role in the development of their autism?
Differences in Vitamin D Status May Account for Unexplained Disparities in Cancer Survival Rates Between African and White Americans (2012)
Conclusion: Compared to white Americans, black Americans generally have significantly lower vitamin D levels, significantly higher rates of vitamin D deficiency, and suffer much more from cancer (which vitamin D-deficiency has been found to be a major culprit in), with worse cancer survival rates than whites.
“This review offers evidence to explain cancer survival differences between AAs [African Americans] and WAs [White Americans]. AAs’ lower serum 25(OH)D concentrations [vitamin D] (mainly from reduced vitamin D photoproduction owing to darker pigmentation) may account for much of the unexplained survival disparity.” Emphasis added.
Conclusion: The vitamin D levels of five different traditionally living indigenous African populations were measured, all ages and both sexes. These are people who spend a lot of time out in the tropical sun. Despite their very dark skin (which can block 90+% of UVB necessary for vitamin D production) the average vitamin D level was about 46 ng/ml, which is substantially higher than levels recorded in western populations. Troubling though, is that despite being at the equator and receiving so much sun exposure, their levels were still just under what most vitamin D experts now consider to be an optimal level. Besides their dark type VI skin, another stated explanation for their sub-optimal vitamin D levels is that they, as with the Hadzabe and Maasai tribes, “avoid direct exposure to the ﬁerce sun whenever possible, and most of their activities are planned in the early morning and late afternoon, while spending the middle part of the day sleeping, eating, or talking in a cooler place under a tree or rock.” By avoiding sunlight and the UVB window at the hottest part of the day, even at the equator vitamin D levels are suboptimal. One woman, however, did have a very high level of 105 ng/ml.
Conclusion: This study investigated whether or not racial vitamin D level differences may play a role in the hypertension disparity between American blacks and whites by examining the vitamin D levels of 1,984 and 5,156 black and white adult subjects and, indeed, it turns out that vitamin D is a major factor in the hypertension disparity.
Possible Role of Serum 25-Hydroxyvitamin D in Black–White Health Disparities in the United States (2010)
Conclusion: “Given the widespread vitamin D deficiency in the AA [African American] population and the potential widespread health benefits that accompany adequate replacement, we believe that addressing this issue may be the single most important public health measure that can be undertaken.” (Emphasis added)
Demographic Differences and Trends of Vitamin D Insufficiency in the US Population, 1988–2004 (2009)
Conclusion: In this study of 32,252 members of the U.S. general population, using data collected from the 1988-1994 Third National Health and Nutrition Examination Survey and 2001-2004 National Health and Nutrition Examination Survey, the Average vitamin D level of hispanics was significantly lower than that of non-hispanic whites, and the average vitamin D level of non-hispanic blacks was even lower. The prevalence of severe vitamin D-deficiency was exponentially higher for blacks compared to whites and hispanics. The study also found that men have slightly higher vitamin D levels than women (who also have a higher rates of severe deficiency) and that younger people have slightly higher vitamin D levels than older people. Although this study shows the glaring racial disparities in the U.S. population’s vitamin D levels, most alarming is that it also found a large decrease in vitamin D levels for all demographics in the time between the two surveys with 77% of all subjects being found to have inadequate vitamin D levels in the second survey. The lower vitamin D levels of darker-skinned people are attributed to their increased amount melanin in their skin, which acts as a natural sunscreen limiting cutaneous vitamin D synthesis from UVB exposure.
Regional Differences in African Americans’ High Risk for Stroke: The Remarkable Burden of Stroke for Southern African Americans (2008)
Conclusion: This article covers how the risk of fatal stroke has been found to be 50-200% higher for black Americans compared to white Americans. Black people tend to have lower vitamin D levels than whites and vitamin D has been found to be a crucial element in cardiovascular health.
Note: Article about the extremely high prevalence of autism among the children of Somali immigrants to Minnesota. Could it be because they are dark-skinned people moving from one of the sunniest areas in the world to an area that gets very weak sunlight, contributing to severe vitamin D deficiency, which may be contributing to the development of autism?
Note: Another article about the extremely high prevalence of autism among the children of Somali immigrants to Minnesota. Could it be because they are dark-skinned people moving from one of the sunniest areas in the world to an area that gets very weak sunlight, contributing to severe vitamin D deficiency, which may be contributing to the development of autism?
Note: And another article about the extremely high prevalence of autism among the children of Somali immigrants to Minnesota. Could it be because they are dark-skinned people moving from one of the sunniest areas of the world to an area that gets very weak sunlight, contributing to severe vitamin D deficiency, which may be contributing to the development of autism?
A Prospective Analysis of Plasma 25-Hydroxyvitamin D Concentrations in White and Black Prepubertal Females in the Southeastern United States (2007)
Conclusion: This study of the vitamin D levels of young girls living in the southeastern U.S. found that 75% had levels below 32 ng/ml (experts recommend maintaining 50 ng/ml), 18% had levels below 20 ng/ml, the white girls had higher vitamin D levels than the black girls, and vitamin D levels fluctuate with the seasons. The study also found that younger girls have higher vitamin D levels than older girls, which may be due to the increased ability of younger people to cutaneously synthesize vitamin D.
Conclusion: Black people have lower vitamin D levels and higher rates of vitamin D-deficiency. This is because the increased melanin in their skin acts a natural sunscreen, blocking the UVB radiation from the sun necessary for cutaneous vitamin D synthesis.
Conclusion: Blacks have a much higher rate of stroke incidence and mortality compared to whites in the United States. This disparity has stubbornly persisted over a period of decades despite advances in stroke-preventing medical treatments. Could this be due to, as many other studies suggest, the consistently low vitamin D levels of the black population?
Serum 25-hydroxyvitamin D concentrations in girls aged 4–8 y living in the southeastern United States (2006)
Conclusion: This study of 168 young girls living in the southeastern U.S. found that those with lower vitamin D levels had a lower bone mineral content, white girls have higher vitamin D levels than black girls (due to the increased melanin preventing vitamin D synthesis), their vitamin D levels dropped in the winter, and their levels increased in the summer. These girls also were found to have higher vitamin D levels compared to girls living at higher latitudes. Despite the black girls having lower pre-vitamin D levels, they had a higher bone density than the white girls. This adds support to findings of people of darker-skinned races possibly have differing vitamin D endocrine systems.
Conclusion: This study of over 3135 people in England found that those of South Asian origin suffer from and seek treatment for chronic musculoskeletal pain much more than white Europeans. The study also found that those suffering from musculoskeletal pain also had lower vitamin D levels, which strongly suggests that the pain is a symptom of vitamin D-deficiency-related osteomalacia. This is due to South Asians having darker skin, which is evolved to protect them from the intense sunlight found closer to the equator. Unfortunately, this darker skin is not well-suited for living in Northern Europe, where it prevents cutaneous vitamin D synthesis in England’s low-sun climate and contributes to chronic, pandemic vitamin D-deficiency among non-whites.
Conclusion: The vitamin D levels of 370 adolescent girls living in the north eastern U.S. were analyzed. The average vitamin D level of all the girls was only a low 21 ng/ml, 17% were found to be severely deficient, and 54% had levels below 20 ng/ml. The average level of the black girls was only 17 ng/ml, with non-black girls having a higher average level of 28 ng/ml (which is still bad). The vitamin D levels were higher in the spring and summer and lower in the fall and winter.
Conclusion: This study of the vitamin D levels of 15,390 American adults found that the men had higher vitamin D levels than the women, white people have higher vitamin D levels than hispanics and blacks (due to increased melanin blocking the UVB necessary for vitamin D synthesis), and although white males had the best vitamin D levels, 34% still tested low. The study also found that elderly people have lower levels compared to younger adults (as we age we slowly lose our ability to cutaneously synthesize vitamin D).
Prevalence and Associations of Vitamin D Deficiency in Foreign-Born Persons with Tuberculosis in London. (2005)
Conclusion: Of 210 London tuberculosis patients, 76% found to have vitamin D deficiency and 56% had undetectable levels. The vast majority of these cases were dark-skinned immigrants from Africa and the Middle East. Dark skinned people living far away from the equator suffer the highest rates of vitamin D-deficiency and related diseases.
Conclusion: Middle-eastern immigrant asylum seekers to northern Europe and the northern U.S. have a high prevalence of severe vitamin D-deficiency and it’s worst symptoms. This is due primarily to their darker skin, evolved to handle intense sunlight, being ill-suited for living far away from the equator in regions with low sun intensity. Exacerbating the problem is the practice of Middle-eastern women wearing veils and hijabs, further blocking the UVB sunlight necessary for vitamin D production. Typical symptoms they seek treatment for are osteomalacia and unspecified musculoskeletal pain.
Nutritional Rickets Among Children in the United States: Review of Cases Reported Between 1986 and 2003 (2004)
Conclusion: This meta-analysis of 22 studies on the prevalence of rickets in American children found that 83% of kids with rickets were black and over 90% were breastfed without any supplementary vitamin D source. People with darker skin types, especially those residing in more northern latitudes, are almost universally are found to have the lowest vitamin D levels and make up a disproportionately higher amount of vitamin D-deficiency diseases and symptoms due to their high melanin content acting as a natural sunscreen blocking the UVB necessary for vitamin D production.This analysis also found that most of the rickets cases were diagnosed in the winter and spring, when population vitamin D levels are the lowest. Five of the studies analyzed that reported cases of white children developing rickets were all from extreme northern states Washington, Minnesota, New York, Connecticut, and New Hampshire, where it is physically impossible for anyone to synthesize vitamin D from sunlight for roughly half of the entire year from autumn to spring.
Conclusion: This article covers a multitude of studies that have found American blacks and American hispanics generally suffer much poorer dental health compared to American whites. Maybe it’s a socioeconomic thing and they can’t afford dentist visits. Maybe it’s a lifestyle thing. Or maybe it’s because vitamin D has been proven to be crucially important in dental and skeletal health, as vitamin D is required by the body to absorb calcium, and dark-skinned people in the west generally have lower vitamin D levels, which would contribute to tooth decay and poor oral health.
Conclusion: Black people in America suffer kidney disease at far higher rate than whites do, with the number of black people undergoing dialysis being quadruple that of whites. As blacks also suffer much higher rates of vitamin D-deficiency, might there be a connection between vitamin D levels and kidney function? Diabetes, which blacks also suffer much more from, has been associated with kidney disease and has also been strongly associated with vitamin D-deficiency.
Also see: Studies Regarding Type-1 Diabetes and Vitamin D and Studies Regarding Type-2 Diabetes and Vitamin D
Hypovitaminosis D Prevalence and Determinants Among African American and White Women of Reproductive Age: Third National Health and Nutrition Examination Survey, 1988–1994 (2002)
Conclusion: The vitamin D levels of 1,546 black women and 1,426 white women in America were analyzed. The average vitamin D level of the black women was only 18 ng/ml, the rate of deficiency was 42%, and the rate of severe deficiency was 12%. White women had a much higher average vitamin D level of 33 ng/ml, the rate of deficiency was 10x less than black women at only 4%, and the rate of severe deficiency was more than 20x less at only 0.5%. One thing to mention is that the definition of vitamin D deficiency/insufficiency in this study was only <15 ng/ml, but most of the world’s leading vitamin D experts now consider anything below to 50 ng/ml to be insufficient. So this means that the rate of insufficiency was actually much, much greater than stated. Either way, this study does demonstrate the great vitamin D disparity between whites and blacks. The black women had 10x the rate of deficiency and an average level less than half of the white women.
Prevalence and Risk Indicators for Destructive Periodontal Diseases in 3 Urban American Minority Populations (2001)
Conclusion: This study found that American blacks suffer poorer oral and dental health compared to Asians and Hispanics. Although this study did not explore vitamin D as a factor, vitamin D has been proven to be a crucial factor in good oral/dental health and dark-skinned people tend to also suffer disproportionately from vitamin D-deficiency.
Note: Article detailing how dark-skinned people suffer disproportionately from type 2 diabetes (2-6x more than white people) and it’s related complications. Could this be due to the well-documented increased difficulty of dark-skinned people to produce adequate vitamin D from sun exposure?
Conclusion: In this experiment white and black subjects were exposed to a dose of ultraviolet light B (UVB) radiation and then vitamin D levels changes were measured. White subjects experienced an increase in their vitamin D levels, but the black subjects did not.
Vitamin D Metabolism Is Altered in Asian Indians in the Southern United States: A Clinical Research Center Study (1998)
Conclusion: Asian Indians are known to have much lower pre-vitamin D levels than Caucasians due to their darker skin limiting cutaneous vitamin D synthesis and are also known to suffer higher rates of severe symptoms of vitamin D-deficiency such as osteomalacia. However, this study of Asian Indians living in the United States found that they have a stronger vitamin D endocrine system than whites. 27 Caucasian adults and 18 Asian Indian adults were put on the same controlled diets containing specific amounts of calcium, phosphorus, sodium, potassium, and vitamin D. Although the Asian Indians had lower pre-vitamin D levels, they had significantly higher activated vitamin D levels than the Caucasians. This altered vitamin D endocrine system, the researchers conclude, however, is not enough to compensate for the vitamin D-deficiency-causing reduction in sun exposure Asian Indians experience when the move farther away from the equator.
Seasonal Changes in Plasma 25-Hydroxyvitamin D Concentrations of Young American Black and White Women. (1998)
Conclusion: This study checked the vitamin D levels of 51 black and 39 white Boston women (ages 20-40 years) four times over the course of one year at each season. At all time points, the black women had lower vitamin D levels. All women had the lowest levels at the end of winter and the highest levels during summer. Although both white and black women experienced rising vitamin D levels from spring to summer, the rise was smaller for black women.
Conclusion: Dark-skinned people living non-equatorial western countries have higher blood pressure than lighter-skinned people in these areas. This is partly because dark-skinned people have extreme difficulty synthesizing adequate amounts of vitamin D from sun exposure in areas like the northern U.S. and Great Britain due to the weakness of the sunlight in those regions and the increased melanin in their skin acting as a natural sun protectant blocking the UVB necessary for vitamin D production.
Conclusion: This study of autism rates in Göteborg, Sweden found that children born from mothers who are Ugandan immigrants to Sweden have a 200x higher risk for autism compared to the general Swedish population. Uganda is literally right on the equator and receives some of the most intense sunlight available on the planet (lots of vitamin D). The sun is so intense that the people there have developed very dark, melanin-rich skin to protect themselves from excess sun exposure. They have more sun than they can handle. Sweden is one of the northernmost territories in the world – rivaled only by Finland, Iceland, Russia, Alaska, and northern Canada. Because of Sweden being so far away from the equator, the country receives very little sunlight compared to Uganda and for months and months out of the year it’s physically impossible to make vitamin D from sunlight. Native Swedes have very light colored skin so they can take full advantage of whatever UVB they do manage to get. It is well-documented that dark-skinned people tend to have lower vitamin D levels than light-skinned people in “developed” countries. In this particular case, you have people with dark-skin living directly at the equator, moving extremely far away north away from the sunny equator in Sweden, where it’s even hard for light-skinned people to get enough vitamin D. If it’s hard for pale native Swede’s to make enough vitamin D, then it’s going to be much, much more difficult, impossible, for dark-skinned people who are used to living at the equator to maintain good health. Indeed, as this study found, their autism rate in Sweden is 200x higher, strongly suggesting that lack of sun exposure is a critical factor in autism development.
Child and Adolescent Psychiatric Presentations of Second-Generation Afro-Caribbeans in Britain (1995)
Conclusion: This study from 1973 to 1989 of second-generation Afro-Caribbean and white children living in a British inner city found that the Afro-Caribbean children had a disproportionately higher rate of autism. Could this be because of the well-documented fact that darker-skinned people are much more likely to suffer from vitamin D-deficiency?
Mild Mental Retardation in Black and White Children in Metropolitan Atlanta: A Case-Control Study (1995)
Conclusion: This study of 893 children in Atlanta, Georgia, U.S. (330 mildly retarded kids and 563 normal controls) found that the rate of mental retardation in black children is nearly double that of white children. Although this study did not explore vitamin D as a factor, it is proven and well-documented that vitamin D is a crucial factor in brain development in utero and during childhood and there is also an overwhelming amount of evidence that blacks disproportionately suffer from vitamin D-deficiency and vitamin D-deficiency-related diseases and disorders due to the high amount of melanin in their skin partially or totally preventing cutaneous vitamin D synthesis from sunlight. It is also well-documented that people with mental disabilities and mental disorders tend to have lower vitamin D levels or have been born from and breastfed by mothers with poor vitamin D levels, and that vitamin D plays a very large role in producing optimal cognitive performance throughout life.
Conclusion: This study of 457 American black people found that those with the darkest skin had the highest blood pressure and that blood pressure increased with increased skin pigmentation. People with darker skin make less vitamin D from sun exposure and vitamin D-deficiency has been strongly associated with high blood pressure.
Conclusion: In this study 12 black adults (7 men, 5 women) and 14 white adults (8 men, 6 women) were put on a diet with identical amounts of calcium, phosphate, magnesium, sodium, and potassium. Despite the black subjects having “significantly lower” pre-vitamin D levels, they had higher activated vitamin D levels and better intestinal calcium absorption than the white subjects. Could it be that dark-skinned people have developed stronger vitamin D endocrine systems to compensate for their reduced ability to cutaneously produce vitamin D from sun exposure?
Conclusion: In this experiment “two lightly pigmented Caucasian and three heavily pigmented Negro volunteers” were exposed to a standard dose of ultraviolet radiation. The UV exposure significantly increased the vitamin D levels of the caucasian subjects, but had no effect at all on the vitamin D levels of the negro volunteers. The experiment was repeated on one of the negros and it ended up taking a UV dose six times larger to produce a vitamin D levels increase similar to that of the caucasian subjects with the original, lower UV dose. According to this study at least, black people need roughly 6x the amount of proper sun exposure to get the same vitamin D level increase as white people.
Conclusion: This survey of 1,000 Detroit adults (ages 25-60) found that those with darker skin had higher blood pressure and that the darker the skin the higher the blood pressure. People with darker skin make less vitamin D from sun exposure and vitamin D-deficiency has been strongly associated with high blood pressure.
Relative Efficiency of Pigment and Horny Layer Thickness in Protecting the Skin of the European and Africans Against Solar Ultraviolet Radiation (1955)
Conclusion: It has been known as far back as 1955 that different skin pigmentations respond differently to solar radiation exposure.