Lundström Petra, Caidahl Kenneth, Eriksson Maria J, Fritz Tomas, Krook Anna, Zierath Juleen R, Rickenlund Anette
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden.
J Nutr Metab. 2019 Mar 3;2019:1840374. doi: 10.1155/2019/1840374. eCollection 2019.
Sun exposure is the main driver of vitamin D synthesis. High latitude, obesity, and type 2 diabetes mellitus (T2DM) are all risk factors for vitamin D deficiency. However, the seasonal variation in vitamin D concentrations (25[OH]D) in such populations before and after sun exposure during the summer is unknown. Therefore, we investigated 25[OH]D status before and after two consecutive summers in high latitude and its associations with body fat, sex, and glucose metabolism.
158 participants from Sweden (87 women, 71 men; mean age, 60 ± 5 y; body mass index ≥ 25 kg/m) and 25[OH]D were measured and evaluated in relation to normal or impaired glucose tolerance, body composition, and dietary habits during summer season.
Eighty-four percent of the participants were categorized with low to deficient 25[OH]D values before summer (55.1 ± 21.7 nmol·L), with a significant increase after the summer season (66.3 ± 21.0 nmol·L; < 0.001). However, the values remained below the recommended range (76-250 nmol·L) in 66% of the participants. These findings were verified in a subgroup of the study population during the subsequent summer. Participants who reported use of vitamin D supplements had higher initial concentrations (64.2 ± 20.1 nmol·L) compared to nonusers (53.7 ± 21.7 nmol·L; =0.04). Further, 25[OH]D values correlated negatively with fat mass (kg) prior to summer only in the female population (=-0.29, =0.008).
In the present study, sun exposure had a beneficial but insufficient effect on 25[OH]D levels, and the same levels were documented in two consecutive summer seasons, confirming that vitamin D supplementation in both summer and winter should be considered in this population.
阳光照射是维生素D合成的主要驱动因素。高纬度、肥胖和2型糖尿病（T2DM）都是维生素D缺乏的危险因素。然而，此类人群在夏季阳光照射前后维生素D浓度（25[OH]D）的季节性变化尚不清楚。因此，我们调查了高纬度地区连续两个夏季前后的25[OH]D状态及其与体脂、性别和糖代谢的关系。
对来自瑞典的158名参与者（87名女性，71名男性；平均年龄，60±5岁；体重指数≥25kg/m）在夏季测量并评估25[OH]D，并与正常或受损的糖耐量、身体成分和饮食习惯相关联。
84%的参与者在夏季前被归类为25[OH]D值低至缺乏（55.1±21.7nmol·L），夏季后显著增加（66.3±21.0nmol·L；<0.001）。然而，66%的参与者的值仍低于推荐范围（76 - 250nmol·L）。这些发现在后续夏季的研究人群亚组中得到验证。报告使用维生素D补充剂的参与者初始浓度（64.2±20.1nmol·L）高于未使用者（53.7±21.7nmol·L；=0.04）。此外，仅在女性人群中，夏季前25[OH]D值与脂肪量（kg）呈负相关（=-0.29，=0.008）。
在本研究中，阳光照射对25[OH]D水平有有益但不足的影响，且两个连续夏季的水平相同，证实该人群应考虑在夏季和冬季都补充维生素D。
