Core Viewpoint - Vitamin D deficiency is not only a concern for osteoporosis patients but also for overweight individuals who struggle to lose weight despite diet and exercise efforts [2] Group 1: Vitamin D Deficiency Prevalence - Vitamin D deficiency is common in China, with a deficiency rate of 18.6% among children and adolescents aged 6-17 and 21.4% among adults aged 18 and above [3] Group 2: At-Risk Populations for Vitamin D Deficiency - Elderly individuals experience decreased skin synthesis of vitamin D due to aging [4] - Homebound individuals with limited outdoor activity may have insufficient sun exposure for vitamin D synthesis [5] - Indoor workers, such as factory or warehouse employees and night shift workers, are at risk due to lack of sunlight [6] - Individuals with darker skin pigmentation may have reduced ability to synthesize vitamin D [7] - Sedentary individuals with low physical activity levels may experience overall health decline, indirectly affecting vitamin D levels [7] - People with chronic or wasting diseases, such as diabetes and chronic kidney disease, may have impaired vitamin D metabolism or absorption [7] - Obese individuals may have lower blood concentrations of vitamin D due to its storage in fat tissue [7] - Post-bariatric surgery patients may have impaired absorption of vitamin D and other nutrients [8] - Certain medications can affect vitamin D metabolism or absorption [8] - Infants born to mothers with vitamin D deficiency during pregnancy or breastfeeding may have low vitamin D levels [9] Group 3: Health Benefits of Vitamin D - Vitamin D plays a crucial role in various health aspects, including bone strength, metabolism, cardiovascular health, mood improvement, maternal and infant health, and diabetes prevention [10][11][12][14] Group 4: Recommendations for Vitamin D Supplementation - Regular sun exposure for about 30 minutes daily is the best way to obtain sufficient vitamin D [15] - Consuming foods rich in vitamin D, such as fatty fish, egg yolks, and fortified products, can help increase intake [16] - High-risk individuals should consider screening for vitamin D deficiency and may need to take supplements under professional guidance to avoid toxicity [17]