I have seen Kefir in the supermarkets and normally ignored them. Spoke to a few of my work colleagues and found out that they have been taking a lot of home made kefir products to keep their immune systems up. They say it works miracles on keeping them healthy when they are close to being sick. 

When you have kids, you are share the love and the sickness too...

What is Kefir? 

• A sour-tasting drink make from cow's milk fermented with certain bacteria. 
• Made from Milk Kefir grains mixed with milk (that has lactose - milk sugar) to allow the bacteria strains to grow.
• Can buy Kefir milk products from supermarkets and the cost is about 3.8 to 5 dollars for 1 L bottle   

What are Milk Kefir Grains?

• Milk kefir grains are a combination of live bacteria and yeasts that exist in a symbiotic matrix on a surface of a complex polysaccharide with a casein core. Kefir grain make-up can vary depending on culturing location and conditions, resulting in a highly variable community of lactic acid bacteria and yeasts. 
  
  Following is a list of bacteria and yeast strains found to comprise kefir grains from different regions and through 2 different scientific studies.* The strains listed may include numerous subspecies and variants. 
  
  

  Bacteria Strains Common to Milk Kefir Grains

  Lactobacillus acidophilus
  Lactobacillus brevis
  Lactobacillus casei
  Lactobacillus delbrueckii subsp. bulgaricus
  Lactobacillus delbrueckii subsp. delbrueckii
  Lactobacillus delbrueckii subsp. lactis
  Lactobacillus helveticus
  Lactobacillus kefiranofaciens subsp. kefiranofaciens
  Lactobacillus kefiri
  Lactobacillus paracasei subsp. paracasei
  Lactobacillus plantarum
  Lactobacillus rhamnosus
  Lactobacillus sake
  Lactococcus lactis subsp. cremoris
  Lactococcus lactis subsp. lactis
  Lactococcus lactis
  Leuconostoc mesenteroides subsp. cremoris
  Leuconostoc mesenteroides subsp. dextranicum
  Leuconostoc mesenteroides subsp. mesenteroides
  Pseudomonas
  Pseudomonas fluorescens
  Pseudomonas putida
  Streptococcus thermophilus 

  Yeast Strains Common to Milk Kefir Grains

  Candida humilis
  Kazachstania unispora
  Kazachstania exigua
  Kluyveromyces siamensis
  Kluyveromyces lactis
  Kluyveromyces marxianus
  Saccharomyces cerevisiae
  Saccharomyces martiniae
  Saccharomyces unisporus

Source Material: Link