Shea butter is the fat pressed from the nut of the shea tree, which grows across the dry belt of West and East Africa. On an ingredient list it appears as Butyrospermum parkii butter. It is one of the better-supported plant fats in skincare, and the list of things it is said to do is much longer than the list of things it does.
What is in it
Most of it is stearic and oleic acid. That mix is why it is solid in the jar and melts against skin.
What sets it apart from other plant fats is an unusually large fraction that does not turn into soap when processed: triterpenes, plant sterols and some vitamin E. Those compounds are behind its reputation for calming irritated skin, and laboratory work supports some anti-inflammatory activity.
What it does
It softens and it seals. The fats fill the gaps between dry surface cells so skin feels smooth, and they slow the rate at which water leaves.
That makes it good for dry, rough, winter skin, and for the places that dry out first: elbows, knees, shins, hands and heels. Small studies on dry and eczema-prone skin found that shea-based moisturisers eased dryness and itch.
Like any fat, it adds no water. It works best over damp skin or in a formula that also contains a humectant such as glycerin.
Raw and refined
Unrefined shea butter is ivory to yellow, smells nutty and slightly smoky, and keeps more of the minor compounds. It also varies from batch to batch and can turn rancid.
Refined shea is white and has no smell. It is more consistent, and it is what most lotions use. Inside a finished lotion, shea is one fat among several, and the formula around it decides how the product feels far more than the grade does.
Claims that do not hold
Sun protection. Shea butter absorbs a small amount of ultraviolet light in laboratory tests. The amount is nowhere near what a sunscreen provides, and using it as one leads to a tan or a burn.
Skin lightening. There is no mechanism and no evidence. Dry skin looks ashy and dull, and it looks better once moisturised. That improvement is real, and it is a change in surface, not in tone.
Stretch marks. Shea keeps stretching skin comfortable. It does not prevent the marks or fade them, for the reasons set out in the stretch marks post.
On the face
Shea ranks lower than coconut oil on the comedogenic scale, though it is still a heavy fat. Dry facial skin usually tolerates it. Oily and acne-prone skin often does not, and coconut oil on the face describes the same problem with a different fat.
This is also why body lotion on the face is hit and miss. Body formulas carry more of these richer fats than most faces want.
Allergy
The shea nut is a tree nut. Refined shea butter contains almost no protein, which is the part that triggers nut allergy, and reactions to it are rarely reported. Anyone with a severe tree nut allergy should still check with their doctor before using it, and a patch test costs nothing.
Where the Cham range fits
The Brightening Body Lotion lists shea butter alongside glycerin, ceramide NP and niacinamide. It is there to do the softening and sealing described above. No other Cham product contains it.
For how a lotion differs from a thicker butter or cream in the first place, cream and lotion compared covers the ratio of water to fat that separates them.
