Vitamin D in the Prevention and Treatment of Osteoarthritis: From Clinical Interventions to Cellular Evidence

Older adults are recommended vitamin D to prevent fractures. Though this population is also at risk of osteoarthritis (OA), the effect of vitamin D on OA is unclear and may differ by disease state. The relationship between vitamin D and OA during OA initiation and progression were considered in this narrative review of in vivo and in vitro studies. Regarding OA initiation in humans, the small number of published observational studies suggest a lack of association between induction of OA and vitamin D status. Most randomized controlled trials were performed in White OA patients with relatively high vitamin D status (>50 nmol/L). These studies found no benefit of vitamin D supplementation on OA progression. However, subset analyses and one randomized controlled pilot trial indicated that vitamin D supplementation may alleviate joint pain in OA patients with low vitamin D status (<50 nmol/L). As the etiology of OA is recently being more fully uncovered, better animal and cell models are needed. According to currently available clinical results, evidence is lacking to set a vitamin D level to prevent OA, and increasing vitamin D status above 50 nmol/L does not seem to benefit OA patients

The effect of calcium intake and vitamin D status on calcium and bone metabolism in females during growth and postmenopause

Adequate intake of calcium and vitamin D are known to benefit bone health in neonates and adults. However, recent observations have suggested that vitamin D status, or serum 25-hydroxyvitamin D (25(OH)D), is not a major regulator of calcium utilization in adolescents. We investigated the effect of supplementing 1000 IU vitamin D/day on calcium balance and fractional calcium absorption in a cross-over design in 11 adolescent girls. Vitamin D status, fractional calcium absorption, and calcium retention were the primary outcome measures. Vitamin D status improved with supplementation. Vitamin D supplementation did not significantly affect net calcium absorption nor retention. However, fractional calcium absorption decreased with vitamin D supplementation. Thus, higher vitamin D status is may not benefit vitamin D-induced fractional Ca absorption in healthy adolescents in the United States. Calcium and vitamin D are interdependent nutrients and should be considered together for calcium homeostasis. We studied the interaction of calcium and vitamin D in female Sprague-Dawley rats during adulthood through estrogen deficiency in a 2 x 3 factorial design. Treatment diets containing either 0.2% or 1.0% calcium and 50, 100, or 1000 IU /kg diet were provided at 8 weeks of age through 4 months post-ovariectomy (OVX; OVX at 12 weeks of age). Continuous monitoring of bone balance through the appearance of bone tracer in urine revealed a protective effect of calcium after estrogen deficiency. An interaction of these 2 nutrients was observed in femoral length and tibial calcium content. Both calcium and vitamin D intake increased endogenous calcium secretion, trabecular bone, and femur width in an independent manner. Calcium intake additionally increased total calcium absorption and decreased bone resorption. Thus, these two nutrients affect both calcium absorption and bone structure, but high calcium and vitamin D status of 50 nmol/L (vitamin D intake 100 IU/kg diet) was optimal for most bone health indicators. In conclusion, vitamin D affects calcium metabolism differently according to life stage and calcium intake. Our results indicate that vitamin D supplementation may not improve Ca absorption during growth or as long as Ca intake is adequate. However, vitamin D may protect bone by affecting the structure of trabecular bone and bone width. High calcium intake may alleviate bone resorption after menopause, regardless of vitamin D status. Future research is required to study the effect of sex and other dietary factors, such as phosphorus, on the interaction of calcium and vitamin D in a dose dependant manner

Low Vitamin D Status Is Associated with Increased Risk of Mortality in Korean Men and Adults with Hypertension: A Population-Based Cohort Study

Background Recent randomized controlled trials (RCTs) have shown no effect of vitamin D supplementation on cardiovascular disease, cancer events and mortality or all-cause mortality in Western populations. However, there has been a lack of research on populations with low vitamin D status, including Asians. In addition, there have been indications that an individual’s sex or hypertension status may affect the relationship between vitamin D status and mortality. In this study, we retrospectively assessed the association between vitamin D status and all-cause, cardiovascular, and cancer mortality in Koreans using a national database, and stratified participants according to sex and hypertension status. Methods Participants in the Korean Health and Nutrition Examination Survey 2008–2014, who consented to their data being synthesized with mortality data (up to December 2019), were included (n = 22,742; mean follow-up: 8.9 years). Participants’ level of serum 25-hydroxyvitamin D (25(OH)D) was measured by radioimmunoassay and categorized as <12, 12–19.9, and ≥20 ng/mL. A Cox proportional hazard model was used to assess the risk of mortality. Results In the total sample, risk of all-cause, cancer, and cardiovascular mortality was greater in adults with a serum 25(OH)D level below 12 and 12–19.9 ng/mL than those with ≥20 ng/mL. Men and adults with hypertension, who had low vitamin D status, had a higher risk of cancer and cardiovascular mortality, but not women or adults without hypertension. Similar results were observed when various cutoffs for 25(OH)D were employed, or extrinsic deaths were excluded. Conclusions Vitamin D status below 20 ng/mL is associated with a higher risk of mortality in Korean adults, especially in men and those with hypertension, on the basis of data from a nationally representative sample. Further RCTs on Asian adults with low vitamin D status are warranted

Development of a Comprehensive Food Literacy Measurement Tool Integrating the Food System and Sustainability

The concept of food literacy is evolving and expanding, increasing the need for a comprehensive measurement tool for food literacy. This study aimed to develop a validated food literacy questionnaire based on an expanded conceptual framework for food literacy. A literature review of existing frameworks and questionnaires for food literacy and focus group interviews (n = 12) were conducted to develop a conceptual framework and candidate questions. A Delphi study (n = 15) and pilot survey (n = 10) to test the preliminary questionnaire’s content and face validity were conducted, which were followed by the main survey (n = 200). Construct validity and reliability were assessed using exploratory factor analysis (EFA) and Cronbach’s alpha, respectively. Criterion validity was assessed by comparing food literacy scores with food knowledge scores (FN-score) and nutrient quotient scores (NQ-score). By integrating and revising the six existing conceptual frameworks and focus group interview results, we proposed a two-dimensional conceptual framework comprising a literacy dimension and a food system dimension. After reviewing 560 items and categorizing them into 18 domains (3 in the literacy dimension × 6 in the food system dimension), 32 questions were selected. As a result of the Delphi study, two items were deleted, and content validity was confirmed for the remaining 30 items (content validity ratio (CVR) = 0.92). Ten items were revised during the face validation process, and five items were excluded as a result of the EFA. The final food literacy questionnaire comprised 25 questions related to five factors: production, selection, preparation and cooking, intake, and disposal. Food literacy scores were positively associated with FN- and NQ-scores, confirming the reliability and criterion validity of the final questionnaire. The two-dimensional food literacy conceptual framework developed in this study systematically encompasses complex food literacy concepts by adding a food systems dimension (production, selection, preparation and cooking, intake, and disposal domain) to the existing literacy dimension (functional, interactive, and critical literacy domain). Based on this integrated conceptual framework, a 25-item food literacy questionnaire was developed and validated for practical use

Genetic Association between Serum 25-Hydroxyvitamin D Levels and Lung Function in Korean Men and Women: Data from KNHANES 2011–2012

The association between single-nucleotide polymorphisms (SNPs) in the vitamin D metabolic pathway and lung function is unknown. We examined the association between five SNPs on DHCR7, GC, CYP2R1, and CYP24A1 along with serum 25-hydroxyvitamin D (25(OH)D) levels and lung function in older Korean men (n = 758) and women (n = 837). Lung function was determined by forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) from the data in the Korea Nutrition and Health Examination Survey 2011–2012. Genetic risk score (GRS) was calculated by the number of 25(OH)D-decreasing alleles of the five SNPs. Our results showed that increases in GRS were associated with reduced 25(OH)D levels (p < 0.05 for both sexes). In the entire population, FVC and FEV1 were associated with both GRS and 25(OH)D levels. In women, FVC and FEV1 were negatively associated with GRS (β-coefficient (95% CI): −0.022 (−0.039, −0.005) and −0.020 (−0.035, −0.005), respectively; both p < 0.05), but not with 25(OH)D. However, in men, FVC and FEV1 were positively associated with 25(OH)D (β-coefficient (95% CI): 0.008 (0.001, 0.016) and 0.008 (0.002, 0.015), respectively; both p < 0.05), but not with GRS. In conclusion, lung function was associated with genetic variation in Korean women and with 25(OH)D in Korean men

Prolonged or Transition to Metabolically Unhealthy Status, Regardless of Obesity Status, Is Associated with Higher Risk of Cardiovascular Disease Incidence and Mortality in Koreans

The risk of chronic disease and mortality may differ by metabolic health and obesity status and its transition. We investigated the risk of cardiovascular disease (CVD) and cancer incidence and mortality according to metabolic health and obesity status and their transition using the nationally representative Korea National Health and Nutrition Examination Survey (KNHANES) and the Ansan-Ansung (ASAS) cohort of the Korean Genome and Epidemiology Study. Participants that agreed to mortality linkage (n = 28,468 in KNHANES and n = 7530 adults in ASAS) were analyzed (mean follow-up: 8.2 and 17.4 years, respectively). Adults with no metabolic risk factors and BMI <25 or ≥25 kg/m2 were categorized as metabolically healthy non-obese (MHN) or metabolically healthy obese (MHO), respectively. Metabolically unhealthy non-obese (MUN) and metabolically unhealthy obese (MUO) adults had ≥1 metabolic risk factor and a BMI < or ≥25 kg/m2, respectively. In KNHANES participants, MUN, and MUO had higher risks for cardiovascular mortality, but not cancer mortality, compared with MHN adults. MHO had 47% and 35% lower risks of cancer mortality and all-cause mortality, respectively, compared to MHN. Similar results were observed in the ASAS participants. Compared to those persistently MHN, the risk of CVD was greater when continuously MUN or MUO. Transitioning from a metabolically healthy state to MUO also increased the risk of CVD. Few associations were found for cancer incidence. Using a nationally representative cohort and an 18-year follow-up cohort, we observed that the risk of CVD incidence and mortality and all-cause mortality, but not cancer incidence or mortality, increases with a continuous or a transition to an unhealthy metabolic status in Koreans

Modulation of Gut Microbiota in Korean Navy Trainees following a Healthy Lifestyle Change

Environmental factors can influence the composition of gut microbiota, but understanding the combined effect of lifestyle factors on adult gut microbiota is limited. Here, we investigated whether changes in the modifiable lifestyle factors, such as cigarette smoking, alcohol consumption, sleep duration, physical exercise, and body mass index affected the gut microbiota of Korean navy trainees. The navy trainees were instructed to stop smoking and alcohol consumption and follow a sleep schedule and physical exercise regime for eight weeks. For comparison, healthy Korean civilians, who had no significant change in lifestyles for eight weeks were included in this study. A total of 208 fecal samples were collected from navy trainees (n = 66) and civilians (n = 38) at baseline and week eight. Gut flora was assessed by sequencing the highly variable region of the 16S rRNA gene. The α-and β -diversity of gut flora of both the test and control groups were not significantly changed after eight weeks. However, there was a significant difference among individuals. Smoking had a significant impact in altering α-diversity. Our study showed that a healthy lifestyle, particularly cessation of smoking, even in short periods, can affect the gut microbiome by enhancing the abundance of beneficial taxa and reducing that of harmful taxa