Hydration

As we age, our skin’s ability to self-moisturise is diminished. This is
an intrinsic ageing process (meaning it will happen irrespective of
environmental factors), but excessive sun exposure can also
accelerate moisture loss. 
 
Dry skin is characterized by a lack of intercellular lipids, natural skin
oils that sit in the intercellular spaces of the epidermis. These lipids
make skin feel smooth and soft. They also perform a vital protective
function, preventing bacteria, viruses and environmental chemicals
from working their way into the spaces between skin cells. When
intercellular lipids are diminished, skin can more easily become
irritated, and feel “tight” or inflamed.
 
Moisturisers rich in Intracellular Lipids (eg. ceramides, cholesterol
and triglycerides), Natural Moisturising Factors (eg. lactic acid,
sodium lactate and glycerin) and Sterols (eg. lanolin) supplement
the skin’s own moisturisers that are depleted by sun and intrinsic
ageing. 
 
Daily use of cosmeceutical vitamins and minerals helps to restore
the skin’s moisture balance, alleviating feelings of sensitivity,
tightness and dryness. Vitamin E is an excellent moisture binder,
while Vitamin B3 (niacinamide) can be used to calm inflammation
caused by dryness. People who are prone to dry skin should be
careful to avoid detergent-based or foaming cleansers, which strip
the skin’s lipid layer leaving the skin dry and exposed.