Taxonomic class

Poaceae

Common Trade Names

Aveeno Cleansing Bar, Aveeno Colloidal, Aveeno Dry, Aveeno Lotion, Aveeno Oilated Bath, Aveeno Regular Bath, Oats and Honey, Oat Bran, Oat Straw Tea, Quaker Oat Bran

Common Forms

Tablets: 850 mg, 1,000 mg

Whole grains, cereals, wafers: 750 mg

Also available as bath preparations, gels, lotions, powders, soaps, and teas.

Source

Oat extracts are derived from the grains of Avena sativa. Oats are cultivated mainly in the United States, Russia, Canada, and Germany.

Chemical Components

Oats contain saponins, carotenoids, gluten, polyphenols, monosaccharides, oligo saccharides, various minerals (such as iron, manganese, and zinc), fiber, and cellulose.

Actions

Oat products have emollient properties when applied topically to dry and pruritic skin. Oat bran cereals and oatmeal contain significant quantities of soluble and insoluble fiber. Dietary fiber is believed to lower cholesterol levels by binding bile acids and cholesterol in the intestines, thus preventing their absorption. Although insoluble fiber is less effective, both forms of dietary fiber appear to reduce serum cholesterollevels.

Reported Uses

Oat extracts have long been used as topical treatments for minor skin irritations and pruritus associated with common skin disorders. Oat herb teas are claimed to be valuable as antigout agents and sedatives.

Several trials suggest that regular intake of dietary fiber from oats can lower serum cholesterol levels in patients with elevated or normal serum cholesterol levels. When combined with other fiberrich foods, these reductions are further increased . Four trials have provided additional clinical support for the value of oats or oat-derived products in treating hyperlipidemia. A randomized, controlled, 6-week comparison of rice bran and oat bran demonstrated statistically significant reductions in cholesterol and LDL levels of about 13% and 17%, respectively .

No beneficial effects were noted for triglyceride or HDL levels. Rice bran performed in a manner similar to that of oat bran but to a lesser degree. In a trial of both normal and hypercholesterolemic Mexican Illen an 8-week regimen of oat bran cookies produced a significant reduction in LDL levels of about 26%, as compared with that of a psyllium group (23%) and a control group (8%). Both active treatments were found to lower cholesterol levels in normal and hypercholesterolemic subjects. No effects were noted for HDL levels, but surprisingly, triglyceride levels were reduced about 28% by the oat bran cookies. Trials conducted by Onning and coworkers demonstrate cholesterol-reducing properties of a novel formulation of oat milk. It has been suggested that the beta-glucans present in oat milk are responsible for the beneficial effects on the lipid profile . These trials also failed to document a significant effect of oat products on serum triglyceride or HDL levels.

Epidemiologic evidence supports a relation between oat bran intake and CV risk as measured by body mass index, blood pressure, and HDL levels . Oat extracts and oat bran bread products also appear to lower blood glucose and insulin levels as well as cholesterol levels but the effects on glucose metabolism have not been consistently demonstrated.

Oat derivatives, such as green oat decoction (tea), may be useful in treating chemical addictions and the extract is being evaluated in smoking cessation programs .

Dosages

For lowering cholesterol, studies used 50 to 100 g of dietary fiber from oat bran P.O. daily.

For topical use, apply once or twice daily.

Interactions

None reported.

Adverse Reactions

GI: bloating, increased urgency of defecation flatulence, fullness, perianal irritation.

Skin: contact dermatitis (oat flour).

Contraindications and Precautions

Oats have been considered to be contraindicated in patients with celiac disease, as are wheat, rye, and barley. Some information suggests that this may not necessarily be the case . Certain oat products may be contaminated with wheat and, therefore, would remain contraindicated for patients with this disorder. Use cautiously in patients with bowel obstruction or other bowel dysmotility syndromes or constipation.

Special Considerations

Advise the patient taking oat bran to regulate bowel habits and drink plenty of fluids.

Advise the patient using colloidal oat products for baths to avoid contact with the eyes and acutely inflamed areas. The products should be washed off with water.

Inform the patient that increased bowel movements and flatulence can occur with ingestion of oat products.

Points of Interest

As with other grains, sometimes oats have been contaminated with aflatoxin, a fungal toxin linked with some cancers.

Commentary

Oats provide an important source of soluble dietary fiber and should be consumed (as with other grains and fibers) regularly as part of a healthy diet. Evidence supports the use of oat extracts and oat products as dietary supplement adjuncts to reduce CV risk factors, but long-term studies examining outcomes are needed. Beneficial effects on total cholesterol and LDL levels are small to moderate, and data on positive effects on HDL levels are lacking. Effects on glucose metabolism are inconsistent. Oatmeal baths may be useful for minor skin irritations, but clinical data supporting this therapeutic application are sparse.