Recipe: Buttermilk and fat free buttermilk substitutes

I found a cookbook called Fat-Free Holiday Recipes by Sandra Woodruff, RD on my cook's library shelves the other day. I was thrilled to say the least. It has many, many recipes I will be able to use. I found some information on buttermilk substitutes in it. It states that you can substitute equal parts of nonfat yogurt and skim milk for buttermilk or mix a tablespoon of vinegar or lemon juice with 1 cup of skim milk and let sit for five minutes before using. For a nondairy alternative it suggests mixing 1 tablespoon of vinegar or lemon jice with 1 cup of soymilk.