Kerastase Nutritive is a line of shampoos and treatments for normal to slightly dry hair.
According to the manufacturer Bain Satin 1 is a shampoo that "creates a fast, velvety lather. It removes residues and prepares the hair for deep nutrition. Hair is infinitely light and nourished, with a brilliant finish."
My experience shows that this is partly true. The lather is very rich indeed, but it tends to turn my hair to one big tangle. I suppose it removes residues all right, and my ultra fine hair does feel light, but in practice it means it is unmanageable and just refuses to hang down. I don't feel my hair is nourished and has a brilliant finish, even after using the Lait Vital treatment. This conditioner is supposed to be left on hair for 2-3 minutes to turn hair silky soft and ultra light. I used this up way before the shampoo as I needed something to make it possible to comb through the tangle the shampoo created and definitely abused the conditioner.
All in all, after using this duo my hair was uncombable, and lacked any shine whatsoever. "Light" for me meant flyaways everywhere and lack of volume.
This is the third Kerastase shampoo and conditioner duo and for sure it's the poorest one. Spending money on them is money well wasted. Any drugstore shampoo will offer the same benefits (or lack of them) for a fraction of the price.