Oats: Adverse Reactions. Interactions. Pregnancy Use.

Adverse Reactions

Excessive intake of fibre from oats or oat bran may cause flatulence and anal irritation.

Significant Interactions

Controlled studies are largely unavailable; therefore, interactions are based on evidence of activity and are largely theoretical and speculative.


Additive effects are theoretically possible; beneficial interaction is possible — observe. Patients taking oats, oat milk or oat bran should be monitored, as medication requirements may alter.


Additive effects are theoretically possible — beneficial interaction is possible. Patients taking oats, oat milk or oat bran should be monitored, as medication requirements may alter. Conversely, two case reports exist of a reduced effect of lovastatin in patients taking 50-100 g oatbran daily. As this is likely to be due to the fibre inhibiting absorption of the drug doses should be separated by 2-3 hours.

Clinical note — Do oats interfere with nutrient absorption?

Although the high phytate content of oats would indicate a potential for reduced absorption of trace elements such as zinc, calcium and iron, one clinical trial investigating the effects of oat bran on zinc absorption found no evidence of reduced absorption.

Contraindications and Precautions


Although oats are generally considered to be contraindicated in patients with coeliac disease, a moderate amount as part of an otherwise gluten-free diet may improve the nutritional value of the diet and is generally well tolerated by the majority of adults and children with coeliac disease. Both short- and longer-term studies have found no adverse immunological effects associated with the regular consumption of moderate amounts of oats in patients with coeliac disease, although some may experience intestinal discomfort, diarrhea, bloating and subtotal villous atrophy.

Dietary oats should not be used in cases of intestinal obstruction.

Pregnancy Use

Oral use is considered to be safe in pregnancy and lactation (NMCD 2003).