Relationship between skin color, sun exposure, UV protection, fish intake and serum levels of vitamin D in Japanese older adults

Abstract

Purpose This paper aims to observe the possible relationship between skin color, sun exposure level, UV protection and food intake and serum levels of 25(OH) D in Japanese older adults. Design/methodology/approach Elderly (n = 131; 65-93 years old), followed by the Tokyo Metropolitan Institute of Gerontology in the Kusatsu (36°N) received a self-applicable questionnaire about the quantity and quality of the daily sun exposure and behavior to avoid the sun. A color analyzer measured each red (R), green (G) and blue (B) component of skin color, and dietary vitamin D was estimated by food frequency questionnaire. Serum 25(OH) D levels were collected and categorized as sufficiency (>30 ng/mL), insufficiency (between 20 and 30 ng/mL) and deficiency (<20 ng/mL). Findings High proportion of participants had insufficiency (53 per cent) and deficiency (25 per cent) levels of 25(OH) D. Insufficiency levels were more prevalent in women (57 per cent, p = 0.048) and in participants that use gloves (49 per cent, p = 0.054) and sunscreen on face (76 per cent, p = 0.003) as a sun protection way. Participants with sufficiency levels of 25(OH) D presented lower values of R (p = 0.067), G (p = 0. 007) and B (p = 0.001) of skin color (what is meaning darker skin) and a higher fish intake (12 times per week). Research limitations/implications The study is a cross-sectional design and brings a potential for measurement error in the recorded subjective variables. There is a memory bias in self-reported sun exposure and food consumption; however, in the multivariate analysis, it was demonstrated a significant association. Second, although the authors have sought to evaluate a number of variables that could affect the skin’s ability to synthesize vitamin D, there are many other factors that may affect this ability that could not be accounted for. Another limitation was the assessment of self-reported ultraviolet exposure data rather than direct measurement of exposure. Practical implications It was also concluded that darker skin color (a surrogate of longer-term sun exposure) participants had a lower prevalence of vitamin D insufficiency in this ethnic homogeneous population. When accessing patients’ skin color, the clinician must account for his or her ethnicity. Social implications Governments should regulate supplementation or food fortification with vitamin D, with special focus in countries with geographical location of insufficient solar radiation for skin synthesis of this vitamin. With this, it becomes a priority that a safe sun exposure ensures the sufficient serum levels of 25 (OH) D without the use of supplements. Originality/value This report was the first to analyze skin color components associated to vitamin D levels, finding that blue and green colors were significant. The clinical implication of this find is yet to understand. It was also concluded that darker skin color (a surrogate of longer-term sun exposure) participants had a lower prevalence of vitamin D insufficiency in this ethnic homogeneous population. When accessing patients’ skin color, the clinician must account for his or her ethnicity.

Serum Vitamin D Concentration ≥75 nmol/L Is Related to Decreased Cardiometabolic and Inflammatory Biomarkers, Metabolic Syndrome, and Diabetes; and Increased Cardiorespiratory Fitness in US Adults

“…Because serum 25(OH)D concentration, triglycerides, glucose, glycohemoglobin, insulin, C-peptide, C-reactive protein, Homeostatic Model Assessment-Insulin Resistance, and homocysteine were skewed, to satisfy the normality, natural logarithm transformed values were used. 3 Homeostatic Model Assessment-Insulin Resistance: Fasting insulin (µU/mL) × fasting glucose (mg/dL)/405.…”

“…The association between serum 25(OH)D concentrations and prevalence of MetS is presented in 3 Significance for the effect of serum 25(OH)D in the multivariable adjusted regression. 4 Data were adjusted for age, gender, race-ethnicity, physical activity, consumption of supplements, smoking status, and alcohol consumption, as well as for interactions between serum 25(OH)D and gender; serum 25(OH)D and race-ethnicity; race-ethnicity and gender; gender and alcohol consumption; and physical activity and alcohol consumption.…”

Validation of Vitamin D-Specific Food Frequency Questionnaire against Food Records for Qatari Women

“…Vitamin D is a lipophilic nutrient that was obtained from the diet and vitamin D supplements. Although vitamin D is synthesized endogenously in the skin when exposed to Sun's UV-B light, the amount of vitamin D that is synthesized in this process is highly variable and affected by several factors, such as latitude, time of the day, skin tone, amount of clothing worn, and use of sunblock lotions [1][2][3]. Interest in vitamin D has grown in recent times because hypovitaminosis D has been found to be related to non-calcemic ailments, such as metabolic syndrome [4,5] obesity [6], diabetes mellitus [7], cancer [8,9], cardiovascular diseases [10], and depression [11].…”

Interaction of Passive Smoking and Diet Habits on Vitamin D Deficiency among Women of Reproductive Age in Rural Central China

“…Some risk factors relative to VD deficiency have been recognized, such as dietary habits and sun exposure [ 14 , 15 ]. Previous studies found that the Japanese elderly population with sufficient levels of 25(OH)D presented with a higher fish intake value (12 times per week) [ 16 ]. A cohort study indicated that the main dietary sources of VD among elderly Germans were fish, eggs, oils, bakery products, and milk or dairy products [ 17 ].…”