这里有一篇文章研究烹调对叶酸含量的影响。看起来除了水煮会比较显著减少叶酸含量以外，其他烹调方式影响并不大。文章中的数据表明水煮蔬菜大约损耗一半左右的叶酸含量，我怀疑主要是溶解在水里丢失了，因为叶酸是水溶性的。蒸菜，炒菜等应该没太大关系。
那么说也不一定非要生吃蔬菜。
http://www.ncbi.nlm.nih.gov/pubmed/12493090
The effect of different cooking methods on folate retention in various foods that are amongst the major contributors to folate intake in the UK diet.
Folate intake is strongly influenced by various methods of cooking that can degrade the natural forms of the vitamin in foods. The aim of the present study was to determine the effect of different cooking methods on folate retention in various foods that contribute to folate intake in the UK diet. Typical purchasing and cooking practices of representative food folate sources were determined from a questionnaire survey of local shoppers (n 100). Total folate was determined by microbiological assay (Lactobacillus casei NCIMB 10463) following thermal extraction and tri-enzyme (alpha-amylase, protease and conjugase) treatment in raw foods and after typical methods of cooking. Boiling for typical time periods resulted in only 49 % retention of folate in spinach (191.8 and 94.4 microg/100 g for raw and boiled spinach respectively; P<0.005), and only 44 % in broccoli (177.1 and 77.0 microg/100 g for raw and boiled broccoli respectively, P<0.0001). Steaming of spinach or broccoli, in contrast, resulted in no significant decrease in folate content, even for the maximum steaming periods of 4.5 min (spinach) and 15.0 min (broccoli). Prolonged grilling of beef for the maximum period of 16.0 min did not result in a significant decrease in folate content (54.3 and 51.5 microg/100 g for raw and grilled beef respectively). Compared with raw values, boiling of whole potatoes (skin and flesh) for 60.0 min did not result in a significant change in folate content (125.1 and 102.8 microg/100 g for raw and boiled potato respectively), nor was there any effect on folate retention whether or not skin was retained during boiling. These current results show that the retention of folate in various foods is highly dependent both on the food in question and the method of cooking. Thus, public health efforts to increase folate intake in order to improve folate status should incorporate practical advice on cooking.
