Summary
Oats can vary in size and color depending on the variety. The wild oat herb can be used both internally and externally to cure many ailments. Wild oat herbs can help with acute and chronic anxiety, kidney ailments, opium and tobacco withdrawal, and insomnia. It can also soothe abdominal fatigue in pregnant women. Oat herb can irritate people who are hypersensitive to gluten.
Description
Medicinal Parts
The medicinal parts are the fresh or dried above-ground plant, the ripe, dried fruits, and the dried, threshed leaf and stem.
Flower and Fruit
The spikelet has 2 to 3 flowers. The outer glume has no awn, is 18 to 30 mm long and has 7 to 11 ribs. The top glumes grow from 12 to 24 mm long, have 2 divisions and a dentate tip. They have 7 ribs and can either be awned or unawned. The awn is 15 to 40 mm long, upright, and rough. The double-ribbed husks are 10 to 20 mm long and are thickly ciliate on the short ridge. The 3 stamens are 2.5 to 4 mm long. The ovary has a pinnatifid stigma. The fruit is 7 to 12 mm long, narrowly elliptoid, and pubescent.
Leaves, Stem, and Root
Oat is a light-green annual grass with a bushy root. The stalks are 60 to 100 cm high, smooth, and glabrous. The linear-lanceolate, tapering, flat leaves are in double rows, and the leaf sheath is clasping. The ligula is short and ovate with triangular pointed teeth. The leaf blade is linear-lanceolate and is 45 cm long by 5 to 15 mm wide.
Habitat
Oats originated in England, France, Poland, Germany, and Russia, and are now cultivated worldwide.
Production
Wild oat herb consists of the fresh above-ground parts of Avena sativa, which are harvested shortly before the height of the flowering season and then quickly dried. Oats consist of the ripe, dried fruits of Avena sativa. Oat bran is taken from the outer layer of the husked fruit. To make rolled oats, the husked fruit is treated with steam, then crushed. Oat straw consists of the dried, threshed leaves and stems of Avena sativa, also harvested shortly before the height of the flowering season.
Other Names
Grain, Groats, Oatmeal, Straw
Actions & Pharmacology
Compounds: Oat Herb
Soluble oligo- and polysaccharides: including saccharose, kestose, neokestose, bifurcose, *beta;-glucans, galac-toarabinoxylans
Silicic acid (partially water-soluble)
Steroid saponins: avenacoside A and B
Unusual amino acids: avenic acid A and B
Flavonoids: including vitexin-, isovitexin-, apigenin-, isoorientin-, tricinglycosides
Effects: Oat Herb
In one poorly constructed experimental investigation, the drug was said to lower the uric acid level and to display an antihepatoxin effect in animal experiments. The mode of action was not explained.
Compounds: Oat Fruit
Starch
Soluble polysaccharides: in particular β-glucans and arabinoxylans
Proteic substances: including gliadin, avenin, avenalin
Peptides: alpha-avenothionine, *beta;-avenothionine
Steroid saponins: avenacoside A and B
Sterols: including β -sitosterol, delta-5-avenasterol
Fatty oil
Vitamins of the B-group
Amines: including gramine
Compounds: Oat Straw
Soluble oligo- and polysaccharides: including saccharose, kestose, neokestose, bifurcose, β -glucans, galac-toarabinoxylans
Silicic acid (partially water-soluble)
Steroid saponins: avenacoside A and B
Unusual amino acids: avenic acid A and B
Flavonoids: including vitexin-, isovitexin-, apigenin-, isoorientin-, tricinglycosides
Effects: Oat Straw
A positive monograph has been issued by Commission E (1987) concerning external use of oat straw with inflammatory and seborrheic skin disease, particularly with itching. The efficacy of the drug has not yet been documented in accordance with valid criteria for the clinical testing of medicinal drugs for the other areas of indication claimed.
Effects: Oat Fruit
Oats limit glycemic and insulin responses to food intake. Dehusked oats are, according to various studies, able to lower blood levels of total and LDL cholesterol in healthy individuals and those with elevated lipid levels. The latest research attributes the cholesterol-lowering effect to the water-soluble polysaccharides, in particular β -glucans. They are also said to hinder prostaglandin biosynthesis. One study has shown Oats to have a positive effect in smoking cessation (Anon, 1997).
Glycemic Control Effects: Providing soluble oat extract in the diet improved glucose and insulin responses to food intake in men and women with moderate hypercholesterolemia (Hallfrisch et al, 1995).
Hyperlipidemic Effects: Studies have demonstrated that the β -glucan content of oat products independently exerted a hypocholesterolemic effect in patients with elevated cholesterol, who follow a National Cholesterol Education Program step 1 diet (Davidson et al, 1991). Taking 40 g of oat bran daily for 14 days enhanced postprandial lipid responses in 6 men with initially normal blood lipid levels. Compared to a low-fiber control diet, 2 weeks on a diet supplemented with oat bran increased plasma levels of free cholesterol, LDL cholesterol, and HDL free cholesterol, and decreased concentrations of plasma esterified cholesterol and HDL esterified cholesterol (Dubois et al, 1995).
Clinical Trials
Cholesterol
A Cochrane Database review identified 10 randomized placebo-controlled trials of apparent quality that examined the effect of consumption of wholegrain foods on cardiovascular disease risk factors and related illness and death in adults. A meta-analysis of these 10 trials showed lower total cholesterol (-0.20 mmol/L; p= 0.0001) and LDL cholesterol (0.18 mmol/L, p<0.0001) resulting from consumption of oatmeal foods. The authors recommend caution in interpreting these seemingly positive effects, however, which typically accounted for risk factors for coronary heart disease but not actual death or coronary events or illness. Cholesterol-lowering and other coronary risk factors reported in these and other trials were recorded over a relatively short period of time (4 to 8 weeks in most cases), and were often small in size and therefore limited in the statistically significant conclusions they could draw. There is a need for adequate and longer randomized studies involving wholegrain foods and diets including whole grains other than oats (Kelly, 2007).
In this randomized, controlled, crossover study, 40 essentially healthy adults despite mildly elevated cholesterol levels were randomly assigned to receive one of three types of muesli cereal two times daily for four weeks. One provided 5 g control fiber from wheat (the control group). One provided 5 g oat B-glucan. The other provided 5 g oat B-glucan plus 1.5 g plant stanols (the “combination muesli”) group. Analysis revealed that consuming muesli enriched with B-Glucan effectively and significantly lowered LDL cholesterol concentrations. Importantly, the addition of plant stanol esters to the B-glucan—the combination muesli—significantly lowered LDL cholesterol concentrations as well (by 4.4%), but less than predicted. The authors hypothesize that this blunted effect may have been due to the impact of B-glucan or possibly the food matrix (Theuwissen, 2006).
A 2005 review examined the cholesterol-lowering powers of National Cholesterol Education Program-recommended combination therapies, one of which involved supplementing the diet with functional foods such as oat bran, plant sterols, and fish oil. Supplements containing these compounds, combined with exercise, decreased total cholesterol, low-density lipoprotein cholesterol, and triglyceride concentrations by 8-26%, 8-30%, and 12-39%, respectively, while increasing high-density lipoprotein cholesterol levels by 2-18%. The two oat bran studies included in the analysis also included exercise. In one, a four-week trial, 13 individuals ingested less than 30% total fat and the equivalent of 100 g of oat bran daily. In another trial, also four weeks long, 235 people ingested less than 30% in the diet and the equivalent of 35-50 g oat bran daily. Consistent and substantial decreases in plasma lipids were found. The authors note a minimal dose of 3 g of B-glucan daily with exercise as the effective regimen for decreasing total cholesterol and low-density lipoprotein cholesterol levels in people with high cholesterol (Varady, 2005).
Oat fiber extract containing a greater amount of β -glucan resulted in significantly lower total cholesterol levels than a low-β -glucan diet in 23 volunteer subjects whose baseline cholesterol levels were between the 50th and 75th percentiles for age and gender. For 7 days the participants received an oat fiber extract containing 1% or 10% soluble β -glucans by weight. This had the effect of replacing 5% of fat energy by an increase in energy from carbohydrate. Both total and LDL cholesterol decreased significantly from baseline levels regardless of the β -glucan content (p<0.0001). The total cholesterol was significantly lower after the 10% β -glucan diet than when subjects took the low-β -glucan diet (p<0.017). LDL cholesterol levels also were lower with the high-β -glucan diet, but the difference was not significant (Behall et al, 1997).
Celiac Disease
A randomized, double-blind, multicenter study was performed with 116 children with celiac disease who were randomized to one of two groups. One group was given a standard gluten-free diet (GFD). The other group was given a GFD with additional, wheat-free oat products over a one-year period. The results indicate that addition of moderate amounts of oats to a GFD does not interfere with clinical or small bowel mucosal healing, or prevent humoral immunological down-regulation in children with celiac disease, indicating that oats may be safely added to the diets of children with the condition (Hogberg et al, 2004).
Diabetes/Heart Disease Prevention
Consumption of a beverage containing oat β -glucans was shown to improve lipid and glucose metabolism in an 8-week, single-blind, controlled study with 5 parallel groups. 100 hypercholesterolemic subjects were recruited; 89 completed the study. During a three-week run-in period, all subjects consumed a control beverage. Over the following five weeks, four groups consumed a beverage with 5 g or 10 g β -glucans from oats or from barley, and one group continued with the control beverage. Compared to control, 5 g of β -glucans from oats significantly lowered total-cholesterol by 7.4% (P<0.01), and postprandial concentrations of glucose (30 min, P=0.005) and insulin (30 min, P=0.025). When compared to control, no statistically significant effects of the beverages with barley β -glucans were found (Biorklund et al, 2005).
Sixteen women and 7 men ranging in age from 38 to 61 years, received a standard diet for 1 week, followed by two 5-week periods of an oat diet or standard diet, using a crossover design. Oat extracts containing 1% or 10% soluble β -glucans replaced carbohydrate and fat in a variety of foods and contributed 10% of energy. At baseline most of the subjects had exaggerated insulin responses to glucose. Insulin scores were 15% lower after taking the 1% β -glucan diet and 24% lower with the 10% β - glucan diet. Insulin responses decreased as the intake of soluble fiber increased. Glucose responses to food intake were reduced by both extracts in both men and women. In women, the 10% extract provided the lowest responses. Glucagon responses to eating were lower after oat extract use in men only. The investigators believe that oat extract can be usefully substituted for fat energy in those who are at risk of diabetes or heart disease (Hallfrisch et al, 1995).
Hypertension
To examine the effect of dietary fiber intake on blood pressure (BP), a randomized, double-blind, placebo-controlled trial was conducted. Subjects (n=110) were recruited who had untreated, but higher than optimal BP or stage-1 hypertension. Participants were randomly assigned to receive 8 g/day of water-soluble fiber from oat bran or a control intervention. Differences were not significant, although oat fibers demonstrated a moderate BP-lowering effect (He et al, 2004).
Skin Disorders
A topical preparation of oat straw, consisting of dried leaves and stems of Avena sativa and containing silicic acid, is used in bath form to relieve itching from inflammatory and seborrheic skin disorders. A dose of 100 g serves for one full bath (Blumenthal, 1998). Severe itching caused by dry skin may be treated symptomatically using a variety of bath products including colloidal oatmeal mixtures, bath soaps and gels, and powders containing oat extracts (Anonym, 1997).
Smoking Cessation
A blinded study suggested that Oats may help smokers to cut down their cigarette use. The 26 smokers participating in the trial received either an alcohol extract of oats or a placebo for 4 weeks. Average daily cigarette use declined from 20 at baseline to 6 at the end of the treatment period, whereas control subjects continued to smoke an average of 17 cigarettes each day. The difference was statistically significant, and responders continued to smoke less, 2 months after treatment ended. These results could not be replicated in a 12-week blinded trial of oat extract (Anonym, 1997).
Indications & Usage
Oat Herb
Unproven Uses
Wild oat herb preparations are used for many purposes, including acute and chronic anxiety, atonia of the bladder and connective tissue, connective tissue deficiencies, excitation, gout, kidney ailments in Kneipp therapy, neurasthenic and pseudoneurasthenic syndromes, old age symptoms, opium and tobacco withdrawal treatment, rheumatism, skin diseases, sleeplessness, stress, weakness of the bladder, and as a tonic and roborant. The efficacy for the claimed applications is not documented.
Homeopathic Uses
Oats are used in homeopathy for exhaustion and insomnia.
Oat Fruit
Unproven Uses
Oat preparations are used for diseases and complaints of the gastrointestinal tract, gallbladder and kidneys, for cardiovascular disorders, constipation, diabetes, diarrhea, physical fatigue, rheumatism, and as a gruel for chest and throat complaints. The claimed efficacy has not been fully substantiated.
Oat Straw
Approved by Commission E:
- Inflammation of the skin
- Warts
The drug is employed externally for seborrheic skin disorders, especially those accompanied by itch.
Unproven Uses
Oat straw is used for abdominal fatigue, bladder and rheumatic disorders, eye ailments, frostbite, gout, impetigo, and metabolic diseases. It is used in foot baths for chronically cold or tired feet. It is also used as a tea for flu and coughs.
Contraindications
Persons with celiac disease should avoid oats.
Precautions & Adverse Reactions
Oat Herb, Fruit, and Straw
No health hazards or side effects are known in conjunction with the proper administration of designated therapeutic dosages. Oats may pose a risk to the rare individual who is hypersensitive to the gluten they contain. Toxic effects of oats, given in moderate amounts, have not been observed in patients with dermatitis herpetiformis, but it remains possible that only large amounts are harmful. Until toxicity is conclusively ruled out and oat products are labeled as being gluten-free, gluten-sensitive patients should be advised to avoid oats (Parnell et al, 1998). Like most fiber products, oat bran products should be taken with large amounts of water to assure that the fiber is well dispersed in the bowel (Anonym, 1997). Contact dermatitis has been reported in persons consuming oat flour.
Atherogenesis
An increase in triglyceride-rich lipoprotein (TRL) secondary to chronic oat bran intake could pose a risk of increased atherogenesis. Not all TRLs have cholesterol-loading properties, and cholesterol ester enrichment was not observed in either large or small TRLs in this study. The postprandial increase in TRL concentration was transient (Dubois et al, 1995).
Drug Interactions
Moderate Risk
Statins
Oat bran may impair absorption and effectiveness of HMG-CoA reductase inhibitors as illustrated by 2 case reports of patients taking lovastatin with oat bran. Low-density lipoprotein (LDL) cholesterol significantly increased in 2 patients taking lovastatin 80 milligrams and oat bran fiber 50 to 100 grams daily for hypercholesterolemia after 4 weeks. When oat bran was discontinued, LDL decreased to baseline levels (Richter et al, 1991). Clinical Management: Administer oat bran two hours before or four to six hours after an HMG CoA reductase inhibitor. If this is not possible, separate administration times as much as possible.
Dosage
Oat Herb
Mode of Administration
The herb is used in combination therapy, as a tea for internal use, and in homeopathic mother tinctures and dilutions.
How Supplied
- Liquid – 1000 mg/mL
Preparation
To make a tea, 3 g drug is boiled in 250 mL water, which is strained after cooling.
Daily Dosage
The tea is taken repeatedly throughout the day and shortly before going to bed.
Homeopathic Dosage
5 to 10 drops, 1 tablet, or 5 to 10 globules 1 to 3 times daily or 1 mL injection solution twice weekly sc (HAB1).
Storage
The herb should be protected from light and moisture.
Oat Fruit
Mode of Administration
The fruit is used in homeopathy and in combination preparations.
Oat Straw
Mode of Administration
As a comminuted herb for decoctions and other galenic preparations as teas and bath additives.
Preparation
To make oat straw bath, 100 g chopped drug is boiled with 3 liters water for 20 minutes and the decoction is added to the bath.
Daily Dosage
100 g of herb is used for one full bath.
