Development and Validation of a Predictive Model of Hypovitaminosis D in General Adult Population: SCOPYD Study

Estimation of the vitamin D (VD) status of pregnant Japanese women based on food intake and VD synthesis by solar UV-B radiation using a questionnaire and UV-B observations

Although vitamin D (VD; serum 25 hydroxyvitamin D) deficiency (< 20 ng/mL) is widespread among Japanese women, the VD status among pregnant women is unknown. This study aimed to determine the VD status of pregnant Japanese women during different meteorological seasons and to determine the factors controlling VD status. A total of 309 pregnant Japanese women were recruited at 28 weeks of gestation at the gynecology department of a university hospital in Tokyo between August 2018 and October 2019. Blood samples were collected to measure serum 25(OH)D levels. Two questionnaires were completed: a brief self-administered dietary history questionnaire (BDHQ) and an outdoor exposure history questionnaire to determine skin sunlight exposure and the use of sunscreen. Among the recruited subjects, 268 were included in the statistical analysis. The average VD intake from food was 9.0 μg/day, the average VD synthesis from UV-B was 15.2 μg/day, and the average sum of VD intake and nominal VD synthesis was 24.1 μg/day; this exceeded the recommended 2011 Dietary Reference Intake for the USA and Canada (15.0 μg/day). However, the average serum 25(OH)D level (11.4 ng/mL) was very low, indicating widespread VD deficiency. Serum 25(OH)D and VD synthesis by solar UV-B were significantly correlated only during the high UV-B season. The 25(OH)D level was weakly correlated with the VD intake from food in all seasons. We obtained a statistically significant correlation between serum 25(OH)D level and VD intake from food using the BDHQ. We also obtained a statistically significant correlation between the serum 25(OH)D level and VD synthesis from solar UV-B exposure, especially during the high UV-B season. Our logistic regression analysis model predicted VD deficiency in 88.0% of subjects. Our method might be possible to be used to predict the VD status of pregnant Japanese women, although another validation cohort is needed to verify the ability of the estimation equation.

Prevention of Recurrent Benign Paroxysmal Positional Vertigo: The Role of Combined Supplementation with Vitamin D and Antioxidants

Benign paroxysmal positional vertigo (BPPV) usually has a favorable course, although it is possible to observe BPPV with a high recurrence rate. Previous studies suggested that vitamin D deficiency might affect BPPV recurrences, and oxidative stress might play a complementary role in BPPV pathogenesis. This multicentric trial aimed to evaluate the effectiveness of oral nutritional supplementation with a compound of alpha-lipoic acid, Carnosine, and Zinc (LICA® (Difass International, Coriano (RN), Italy)), vitamins of group B and vitamin D in preventing BPPV recurrences. A total of 128 patients with high recurrence-BPPV were randomized in three arms: Arm 1 consisted of subjects with “insufficient” or “deficient” vitamin D blood levels, treated with daily oral supplementation of LICA®, vitamins of group B and vitamin D3 (800 UI), Arm 2 included BPPV subjects with “sufficient” vitamin D who did not receive any nutritional support, and Arm 3 included subjects with a “sufficient” serum concentration of vitamin D who received supplementation with a compound of LICA® and Curcumin. After six months of follow-up, a significant reduction of BPPV relapses compared to the baseline was found only in Arm 1 (−2.32, 95% CI: 3.41−1.62, p-value < 0.0001). Study results suggested that oral nutritional supplementation with vitamin D3 plus antioxidants can prevent relapses in patients suffering from high recurrence-BPPV.

Vitamin D Status in Japanese Young Women in 2016-2017 and 2020: Seasonal Variation and the Effect of Lifestyle Including Changes Caused by the COVID-19 Pandemic

Avoidance of sunlight and self-restraint due to the COVID-19 pandemic may contribute to reduced vitamin D status. This study provides comparable data on vitamin D status in Japanese young women and assesses the effect of lifestyle, including changes caused by the COVID-19 pandemic, on vitamin D status. In study 1, 39 young healthy Japanese women aged 21-25 y were recruited from May 2016-June 2017. Serum 25-hydroxyvitamin D (25OHD) concentration and diet and lifestyle information were obtained from participants each month (n=124). In study 2, using the same parameters as study 1, young women aged 21-23 y (n=10) were recruited in September 2020. In the results of study 1, we found the frequencies of vitamin D deficiency (25OHD<20 ng/mL) in spring, summer, fall, and winter were 90.5%, 62.5%, 81.5%, and 91.3%, respectively. The substantial difference of serum 25OHD concentration was obtained in spring (Δ3.6 ng/mL) and summer (Δ5.1 ng/mL) depending on the frequency of sunscreen use (0-2 d/wk, 3-7 d/wk). In study 2, serum 25OHD concentration in September 2020 was extremely lower than in September 2016 (13.2 ng/mL vs. 21.7 ng/mL). The number of days spent outside in 2020 decreased drastically compared with 2019. In conclusion, vitamin D deficiency was highly common in Japanese women in their early 20s, and frequent sunscreen use contributed to low vitamin D status. Moreover, because the decrease in days outside due to the COVID-19 pandemic obviously resulted in a decline in vitamin D status, both appropriate sunbathing and increased dietary vitamin D intake are recommended to young women.

Predictive Ability of Machine-Learning Methods for Vitamin D Deficiency Prediction by Anthropometric Parameters

Background: Vitamin D deficiency affects the general population and is very common among elderly Europeans. This study compared different supervised learning algorithms in a cohort of Spanish individuals aged 35–75 years to predict which anthropometric parameter was most strongly associated with vitamin D deficiency. Methods: A total of 501 participants were recruited by simple random sampling with replacement (reference population: 43,946). The analyzed anthropometric parameters were waist circumference (WC), body mass index (BMI), waist-to-height ratio (WHtR), body roundness index (BRI), visceral adiposity index (VAI), and the Clinical University of Navarra body adiposity estimator (CUN-BAE) for body fat percentage. Results: All the anthropometric indices were associated, in males, with vitamin D deficiency (p < 0.01 for the entire sample) after controlling for possible confounding factors, except for CUN-BAE, which was the only parameter that showed a correlation in females. Conclusions: The capacity of anthropometric parameters to predict vitamin D deficiency differed according to sex; thus, WC, BMI, WHtR, VAI, and BRI were most useful for prediction in males, while CUN-BAE was more useful in females. The naïve Bayes approach for machine learning showed the best area under the curve with WC, BMI, WHtR, and BRI, while the logistic regression model did so in VAI and CUN-BAE.