These natural ingredients are labeled as such because they
consist of extracts derived directly from plants or animal products;
however, unlike some products marketed as “organicâ€,
their constituents have been dermatologically tested for the
pharmacology grade purity, efficacy, and safety demanded
from modern medicine.1,2
Colloidal Oatmeal
Derived from the common or wild oat (Avena sativa), colloidal
oatmeal has a long history of traditional folk use dating back to
2000 BC in Egypt and the Arabian peninsula. Oats have been
used internally and externally for various conditions, most
prominently skin ailments. Oatmeal baths were popular even
in the 19th century for pruritic and irritant dermatoses. Colloidal
oatmeal stands out among the natural products since it has even
been officially recognized by the FDA for its anti-pruritic and skinsoothing
properties in the context of eczema and contact allergy.
It stems from dehulled oat kernels that are ground into a very
fine powder that is readily dispersible in water. Most of the constituents
of the powder are less than 75 microns in particle size,
allowing for superior dispersion and permitting its formulation
as topical skin care and bath products. Colloidal oatmeal consists
of various oat fractions including 2% to 11% of lipids, up to
64% of sugars and amino acids, 12.5% to 18% of vitamins including
A, E, B, and saponins, flavonoids, prostaglandin inhibitors,
and just a very small fraction of 0.06% avenanthramides.
Ongoing research has provided new data on the function of
each of these subfractions. Colloidal oatmeal proteins have
been shown to be capable of buffering both acids and bases.
Oatmeal has many components that repair or preserve barrier
function. Its proteins and polysaccharides bind to the skin and
provide a protective barrier to external insults. The anti-pruritic
activity of colloidal oatmeal is generally attributed to its ability
to maintain barrier integrity and protect against external insults,
its ability to moisturize the skin and alleviate itching due
to lack of hydration and abnormal subcutaneous buildup arising
from abnormal desquamation, and its anti-inflammatory
components, such as linoleic acid, which have been shown to
reduce skin inflammation. It is able to bind to the skin and help
form a barrier that reduces TEWL and also helps prevent the entry
of environmental irritants. An additional barrier-protective
and anti-pruritic effect derives from oatmeal’s hydrocolloid effect,
which creates a film that stays on the skin.2-12
A newly discovered oat fraction, avenanthramides are the
principle polyphenolic antioxidants in oats and have been
shown to exert their anti-inflammatory properties via NF-ϰb
activation and inhibition of pro-inflammatory cytokines in
keratinocytes. In one study on mice, researchers were able
to demonstrate the ability of avenanthramides to block the
irritation associated with contact hypersensitivity in a dose
dependent response, with activity of the 3% avenanthramide
formulation comparable to 1% hydrocortisone. In a skin erythema
model, separated oat fractions were tested to further
explore the functional properties of various oat components.
Compared with other oat subfractions, the avenanthramide
fraction most effectively reduced ultraviolet (UV)-induced
erythema 24 hours after skin application. In preclinical models,
avenanthramides were found to decrease the stimulated
release of interleukin 8 (IL-8) from human epidermal keratinocytes.
Significant reductions of IL-8 release were obtained
with 1, 10, and 100 μg/mL avenanthramides (P<.05). Clinical
studies indicate that avenanthramides may be of particular
value in restoring the cutaneous barrier and reducing symptoms
of AD. It is therefore not surprising that clinical efficacy
of colloidal oatmeal has been demonstrated in such varied
skin conditions as AD, contact dermatitis, fungal infections,
seborrheic dermatitis, burns, and postchemotherapy dermatologic
toxicity.7-12
New focus has been shifted onto the various lipid components
within the oat subfractions. When fractionated, whole
oat oil is composed of a mixture of lipids, falling into 4 main
lipid classes: triglycerides, diacylglycerol, phospholipids, and
free fatty acids, with smaller amounts of sterols, phosphatidylethanolamine,
and other compounds. The buffering capacity of
colloidal oatmeal restores the pH of damaged skin to within the
normal range, a capacity that has been well documented in the
medical literature since the early 1950s.
In another early clinical study, colloidal oatmeal was used as
a bath and a cleanser for 3 months by 139 patients aged 21
to 91 years with various pruritic dermatoses, and was able to
achieve complete or marked relief in more than 71% of these
patients.5 It has also been used successfully in the treatment
of burn patients, promoting skin healing.7 More recently, colloidal
oatmeal has been shown to provide symptomatic relief
of the dermatologic side effects of chemotherapy, specifically
in the treatment of the acneiform eruption induced by epidermal
growth factor receptor and multiple tyrosine-kinase
inhibitors.8 Similarly it has been effective in controlling the
pruritus caused by erlotinib.9
Infants and children aged 2 months to 6 years suffering from
AD, contact dermatitis, or seborrheic dermatitis were treated
with a colloidal oatmeal cream and cleanser for 4 weeks. Dermatologist
evaluation at weeks 2 and 4 showed significant