The Uncertain Significance of Low Vitamin D Levels in African Descent Populations: A Review of the Bone and Cardiometabolic Literature

O’Connor, Maeve; Thoreson, Caroline K; Ramsey, Natalie; Ricks, Madia; Sumner, Anne E.

doi:10.1016/j.pcad.2013.10.015

Cited by 31 publications

(28 citation statements)

References 75 publications

(109 reference statements)

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“…Therefore, African descent populations with low vitamin D levels, could potentially be treated with increased exposure to sunlight. However, cutaneous production of precursors to 25(OH)D represents a balance between exposure to sunlight and the melanin content of the skin; the former increases and the latter decreases cutaneous production of vitamin D precursors(33). …”

Section: Discussionmentioning

confidence: 99%

Biochemical and clinical deficiency is uncommon in African immigrants despite a high prevalence of low vitamin D: the Africans in America study

et al. 2015

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Purpose The Endocrine Society and Institute of Medicine (IOM) have concluded from studies in largely white populations that 25(OH)D is necessary for bone health. However, their definition of vitamin D insufficiency differs. The Endocrine Society recommends a 25(OH)D threshold of <30ng/mL. The IOM uses a lower threshold of 25(OH)D <20ng/mL. As African ancestry is associated with decreased 25(OH)D but increased bone mineral density (BMD), the applicability of these thresholds to Africans is unknown. Therefore, we examined in African immigrants the relationship of 25(OH)D to parathyroid hormone (PTH) and BMD. Methods One-hundred-eighty-six African immigrants (69% male, age 38±10 (mean±SD) range 20–64y) living in metropolitan Washington, DC were enrolled. BMD was determined from whole-body DXA scans. Decreased BMD required T-scores ≤ −1.0. The threshold for low 25(OH)D was the concentration of 25(OH)D at which PTH became suppressed. This is known as the inflection point. Biochemical deficiency required low 25(OH)D and PTH>65 pg/mL. Clinical deficiency required low 25(OH)D and T-scores ≤ −1.0. Results 25(OH)D<30ng/mL and <20ng/mL occurred in 83% and 46% of African immigrants, respectively. PTH inversely correlated with 25(OH)D (r = −0.31, P=0.002). The inflection point occurred at a 25(OH)D concentration of 20ng/mL. Biochemical and clinical deficiency occurred in only 8% and 3% of immigrants, respectively. Conclusion As PTH became suppressed at 25(OH)D of 20ng/mL, the 25(OH)D<20ng/mL threshold for insufficiency may apply to African immigrants. However, ~50% of African immigrants have 25(OH)D<20ng/mL, but only <10% had evidence of deficiency. The value of providing vitamin D supplementation to the large number of African immigrants with 25(OH)D<20 ng/mL and no detectable evidence of deficiency needs to be determined.

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Section: Discussionmentioning

confidence: 99%

Biochemical and clinical deficiency is uncommon in African immigrants despite a high prevalence of low vitamin D: the Africans in America study

et al. 2015

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“…Irradiation of 7‐dehydrocholesterol in the epidermis leads to the production of vitamin D3. According to O'Connor et al ., in a study published in Progress in Cardiovascular Diseases , ‘The amount of vitamin D3 produced depends on the balance between the availability of UVB light and the amount of melanin in the epidermis. Due to high exposure to UVB, Africans living in equatorial countries should have high endogenous production of vitamin D3.…”

Section: What About Vitamin D?mentioning

confidence: 99%

“…Three of the four studies from equatorial regions that they reviewed showed high levels of vitamin D; the fourth indicated low levels. One study of South Africans reviewed by O'Connor et al 9 reports sufficient levels of 25hydroxyvitamin D, and two suggest low levels. O'Connor et al speculate that 'vitamin D levels might be lower in black South Africans than equatorial Africans.…”

Section: What About Vitamin D?mentioning

confidence: 99%

Skin cancer: an African perspective

Gohara¹

2015

Br J Dermatol

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SummaryThe objective of this review article is to assess skin cancer and sun protection trends in darker-skinned Africans. The published information suggests that in order to reduce the skin cancer mortality rate amongst people of colour, a broader effort towards public awareness/education is necessary.What's already known about this topic?• There have been review articles published examining skin cancer amongst people of colour in sub-Saharan or north Africa. What does this study add?• This article looks at skin cancer in all of Africa, not just the north or south.• It looks at skin cancer/sun protection practices in Africa.• It examines African skin cancer trends and puts them in a global context. When approaching nonwhite African populations, issues related to skin cancer might not be at the forefront of their minds. Although cutaneous malignancies are not extremely common within this group, mortality rates remain much higher compared with their white counterparts.1 It can be inferred that these discrepant outcomes may be attributed to both late detection and/or biologically more aggressive tumours. In order to prevent future skin cancer-related deaths amongst those with brown skin, teaching all patients, regardless of ethnicity, about sun protection, the importance of skin checks and the risk factors associated with cutaneous malignancy is critical. Sun protection and skin cancer perceptions amongst nonwhite AfricansSkin cancer and disorders of pigmentation make protection against ultraviolet (UV) rays an issue of paramount importance. Is this message getting across to the diverse African population? Although a few published studies have attempted to answer this question, the available data show that much more education is needed. Meziane et al.3 examined the results of a Moroccan public awareness campaign created to teach north-African citizens about the sun's deleterious effects. Four hundred and eleven participants, who varied in age, sex, socioeconomic status, education level and skin type (Fitzpatrick I-V), were surveyed on sun safety. Sixty-four percent of respondents had a 'poor' or 'bad' understanding of solar risk, and the majority of those with skin types IV and V had a 'poor' or 'bad' understanding of solar risk. Fewer than 50% of the participants had ever purchased sunscreen; 75% believed that one application was sufficient for all-day coverage; 15% used hats for sun protection; 19% used sunglasses for sun protection; 32% knew to avoid the sun between 10Á00 and 16Á00 h; and most were not aware of the connection between sun exposure and hyperpigmentation. Women and those with

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“…Several international organizations agree that vitamin D is important for bone health in adults and elderly subjects but disagree on the level of serum 25OHD which must be achieved for this aim: IOM [59] and several European agencies (Nordisk countries, the Netherlands, German speaking countries) recommend serum 25OHD concentrations above 20 ng/ml, whereas a task force of the Endocrine Society recommended >30 ng/ml, and others recommend even higher levels [60]. It has also to be noted that most intervention studies were performed in elderly Caucasians, and therefore the beneficial effects have not been fully proven in younger postmenopausal women or in individuals with different ethnic background such as Afro-Americans and Asians [61]. The same conclusion is true for the effects of vitamin D (supplementation) in older children and adolescents [62].…”

Section: Osteoporosis: Role Of Vitamin D Supplementationmentioning

confidence: 99%