Dear SimonFerments, Please save yourself a lot of money. Good kefir will blow your pills and even homemade yogurt out of the water without any trouble whatsoever. One of your probiotic pills will have something like 8 billion wigglers in it, of limited variety. A 1/4 cup of kefir will have a trillion wigglers of more than 30 to 54 different species, depending upon whether you believe Marilyn Kefirlady or Dom.
I did yogurt for decades. Kefir is much cheaper, much simpler, and much more healthy.
I was also a pill popper for decades. I put a lot of people through college buying all of those pills. I had a box of pills to take every day. And frankly, it didn't even come close to the benefits that I can feel with paleo and fermented.
The pill popping is partialistic or fractional thinking, rather than holistic thinking. I even did the partialistic thinking when I knew it sucked, so don't take my observations as a criticism. My pill taking has dropped dramatically since I went paleo and more recently fermented. You are still going to need Vitamin D, but I even take fewer Vita. D because of my taking cod liver oil. Now, I take very few pills. It used to be dangerous for me to down all of my pills at once; now I look into the little pill jar and wonder where all the pills went.
Once you get started with kefir, and you treat your grains right, you will never have to spend another cent on dairy fermentation, and it will be much healthier than yogurt or any pills.