THE AUTUMN equinox(昼夜平分点，春分或秋分), which fell this year on September 23rd, is a glum(忧郁的，闷闷不乐的) milestone, at least for people in the northern hemisphere. The days are shortening and the nights lengthening; around the equinox they cross over, and the winter gloom begins in earnest(正式地，认真地开始).
今年的秋分落在9月23日。至少对北半球的人来说，这是一个令人沮丧的节点。白昼渐短，黑夜渐长；到了秋分前后，昼夜长短发生逆转，冬日的阴郁便正式开始了。
One group that might welcome the shorter days is the supplement(补充剂，保健品) industry. Sunlight—specifically, the chemical reactions caused by ultraviolet radiation(紫外线辐射) falling on bare skin—is necessary to make vitamin D, a compound(化合物) vital for health. As the sunlight fades, interest in vitamin D supplements—as measured by(以……来衡量) searches on Google—rises.
有一个群体或许会欢迎白昼变短，那就是保健品行业。阳光——确切地说，是紫外线照射裸露皮肤所引发的化学反应——是合成维生素D的必要条件，而维生素D是一种对健康至关重要的化合物。随着阳光渐弱，人们对维生素D补充剂的兴趣——以谷歌搜索量衡量——也随之上升。
In fact, vitamin D is one of the most popular supplements on the market. One paper published in 2017 reported that 18% of Americans took large doses of supplementary vitamin D in 2013-14, up from 0.3% in 1999-2000.(2017年发表的一篇论文报告称，2013至2014年间18%的美国人服用过大剂量维生素D补充剂，而1999至2000年这一比例仅为0.3%。) More than 10m blood tests are performed to measure levels of the stuff each year. In Britain and Iceland supplements come with the government’s stamp of approval(官方认可，批准).
事实上，维生素D是市场上最畅销的补充剂之一。2017年发表的一篇论文报告称，2013至2014年间，18%的美国人服用过大剂量维生素D补充剂，而1999至2000年这一比例仅为0.3%。每年有超过1000万次血液检测用于测量体内维生素D水平。在英国和冰岛，补充剂还获得了政府的认可。