I have been reading so many good things about drinking kefir that I just had to try it. Kefir is a type of fermented dairy product, much like yogurt, but with many more probiotics. This makes it even healthier for you than your average yogurt. Even folks who have some problems digesting cow's milk (like me) can manage kefir. You can drink it plain, make it into smoothies, or use it in recipes.
Milk kefir grains can be obtained from friends or from the Internet. They look a bit like cauliflower or like tapioca. They are placed in a container of milk and they feed off the milk for the day. They grow and can be used again and again. You can use cow, goats, or sheep milk. Some people also use coconut milk, but this is less successful from what I read, and the grains really need to be fed milk to thrive. I may try to use coconut milk occasionally once my grains have grown a bit more.
I purchased my grains from Kefirshop in the UK for £12. I received a very small plastic pouch of grains with a bit of milk and instructions. I placed them in a jar. Now, this company suggests that you use plastic in case the whole thing explodes. But many websites suggest using a glass jar. To begin with, you need to use only a little milk---200 ml or so until they grow. It is also a good idea to only drink a small amount to get your body used to it. So you will increase your consumption over the weeks and the grains will also be producing more for you.
The most exciting thing for me was to discover that my Other Half loves it. In fact it is exactly like the fermented milk he grew up drinking in Tanzania. The fermented milk there is produced slightly differently in that the traditional way is to place the milk in a gourd which hangs in the kitchen. During the day this gourd is swung about to mix the milk. In the morning it is emptied, sugar added to the milk, and it is often served with maize porridge. The gourd is not washed, so the residue from the previous milk helps to ferment the next day's batch. (This is similar to how yogurt is made).
There is a lot of information about kefir available on the Internet. One useful site is The Healthy Home Economist. This includes a video on how to make it.