There are many reasons people go vegan, from wanting to be healthier, to reducing their environmental footprint, to concerns about animal welfare.

　　人们吃素的原因有很多种，例如，想要变得更健康，减少对环境的影响，以及关注动物福祉。

　　No matter what the reason, many people find it difficult to meet the nutrient intaketargets for specific vitamins and minerals while on a vegan diet. These include vitamin B12, iron, calcium, and iodine.

　　不论大家吃素的原因是什么，许多人发现，吃素无法满足对特定维生素和矿物质的营养摄入量的需求，其中包括维生素B12、铁、钙和碘。

　　1.Vitamin B12

　　维生素B12

　　Vitamin B12, or cobalamin, is essential for making red blood cells, DNA (your genetic code), fatty acids located in myelin (which insulate nerves), and some neurotransmitters needed for brain function.

　　维生素B12也就是钴胺素，它是形成红细胞、DNA(你的基因序列)、髓磷脂(隔离神经的物质)中的脂肪酸以及发挥大脑机能所需的部分神经介质的必要物质。

　　Vitamin B12 is stored in the liver, so a deficiency probably won't happen in adults in the short term.

　　维生素B12可以贮存在肝脏中，所以成年人短期内不会出现维生素B12缺乏的症状。

　　2.Calcium

　　钙

　　Calcium is needed to develop and maintain the skeleton bones, and is stored in the teeth and bones. It is also essential for heart, muscle and nerve function.

　　钙是骨骼生长发育所需的元素，它可以贮存在牙齿和骨骼中。它也是发挥心脏、肌肉和神经功能的必要元素。

　　3.Iodine

　　碘

　　Iodine is needed to make thyroxine, a thyroid hormone used in normal growth, regulation of metabolic rate, and development of the central nervous system. Iodine is concentrated in the thyroid gland.

　　碘是合成甲状腺素所需的元素，这是一种甲状腺激素，可以控制并促进正常的新陈代谢，也有助于中枢神经系统的发育。碘主要贮存于甲状腺中。

　　4.Iron

　　铁

　　Iron is needed to make haemoglobin in red blood cells, which carries oxygen around your body.

　　铁是合成血红蛋白所需的元素，而血红蛋白是人体内运输氧的物质。

　　Iron is also needed for the production of energy in your muscles, and for concentration and a healthy immune system.

　　铁也是肌肉产生力量所需的元素，而且它可以提高人体免疫力并有助于维持免疫系统的健康。