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Food as Medicine: Oat (Avena sativa, Poaceae)

Editor’s Note: Each month, HerbalEGram highlights a conventional food and briefly explores its history, traditional uses, nutritional profile, and modern medicinal research. We also feature a nutritious recipe for an easy-to-prepare dish with each article to encourage readers to experience the extensive benefits of these whole foods. With this series, we hope our readers will gain a new appreciation for the foods they see at the supermarket and frequently include in their diets. We would like to acknowledge ABC Chief Science Officer Stefan Gafner, PhD, for his contributions to this project.

By Hannah Bauman

Overview

Woven baskets hold green oat pods

Avena sativa is a member of the grass (Poaceae) family and an annual with tall, hollow stems that can grow up to 1.2 meters (approximately four feet) in height.1,2 The stems produce flat, bladelike leaves and loosely branched inflorescences, or panicles, that produce golden seeds. These seeds, or groats, are the main part of the plant used commercially, though all of the above-ground parts have been used traditionally. When unripe, the seeds are referred to as “green” or “milky” oats. Ripened seeds are dried and often processed into flakes for human consumption.

Oats are native to the Eurasian continent, with a range that covers the Mediterranean, North Africa, Europe, and Northern Central Asia, and have been cultivated by humans for 2,000-5,000 years.2,3 Avena sativa is thought to be descended from wild red oat (A. fatua). It grows well in cool, damp climates but is adaptable and tolerates soil with high salinity.

Historical and Commercial Uses

Traditionally, both dried and fresh oats have been used for a wide variety of conditions including anxiety, stress, skin diseases, bladder disorders, blood vessel and lung ailments, and gastrointestinal disorders.1 In the modern Western herbal tradition, oats are considered a nervine, relaxant, antispasmodic, antidepressant, demulcent, and restorative.4 In the US Eclectic medical tradition of the 19th and early 20th centuries, oats were used, in the words of physician Finley Ellingwood, MD, as a “remedy of great utility in loss of nerve power and in muscular feebleness from lack of nerve force.”5

Milky oats have also been used, particularly in Indian medicinal practices, as a therapy for opium and tobacco (Nicotiana tabacum, Solanaceae) addiction and to ease the symptoms of withdrawal.3 In traditional Persian medicine, oats were used topically for their emollient effects and added to baths, poultices, and creams to soothe inflamed or itchy skin and other skin disorders.6 In a survey of men and women in northwest Pakistan, A. sativa was among the top 12 most commonly identified plants used in medicinal practice, where oats were fried in ghee (clarified butter) and milk to make a paste that was used as an aphrodisiac and general body tonic.7

Botanical illustration of the oat plant, 1880Though oats were used in traditional medicinal practices, they were most often cultivated as a source of food for livestock and humans. The top oat-producing countries are Russia, Canada, the United States, and Poland.2 Oat ranks sixth after corn (Zea mays, Poaceae), rice (Orzya sativa, Poaceae), wheat (Triticum aestivum, Poaceae), barley (Hordeum vulgare, Poaceae), and sorghum (Sorghum bicolor, Poaceae) in world grain production, though oat production has increased significantly since the 1990s.8 The oat plant accumulates calcium and magnesium and is often used as a cover crop to regenerate soil.4

As a food product, oat seeds are dried and sold as either whole groats (“Scottish-style” oatmeal), flattened into flakes (rolled oats), or flattened and pulverized for “instant” oatmeal. Oatmilk is growing in popularity as a dairy-free alternative for those who are lactose intolerant or vegan. Oats can also be used in the grain mash to make beer.

Several standards-setting organizations have recognized the positive effects of oat and its constituents on human health. The European Food Safety Authority (EFSA), an agency of the European Union, allows foods with oat ingredients that contain at least six grams of fiber per 100 grams to use the health claim that “Oat grain fiber contributes to an increase in fecal bulk.”9 In addition, foods containing at least four grams of oat-derived beta-glucans (also written as “β-glucans”) per 30 grams of carbohydrates can use the following language: “Consumption of β-glucans from oats as part of a meal contributes to the reduction of the blood glucose rise after that meal.” EFSA also concluded that “oat beta-glucan has been shown to lower/reduce blood cholesterol. Blood cholesterol lowering may reduce the risk of (coronary) heart disease.”10 The US Food and Drug Administration approved a health claim for oat-derived beta-glucan for the reduction of plasma cholesterol levels and risk of heart disease and the United Kingdom Joint Health Claims initiative also allowed a cholesterol-lowering health claim for oats.2 Oat and oat extract are common ingredients in modern skin care products such as body lotion due to their soothing, anti-inflammatory properties.

Phytochemicals and Constituents

Oat groats are a good source of dietary fiber, which contributes to healthy gastrointestinal function and can help prevent disorders including colonic diverticulitis and constipation.9 Oat also contains macronutrients including protein, B vitamins such as thiamin, vitamin E in the form of alpha-tocopherol, and minerals such as manganese, magnesium, and phosphorous.2 Among cereal grains, oat is notable for having a high protein content, ranging from 15%–20% of the groat by weight.8

Beta-glucans are a type of polysaccharide, which is a form of dietary fiber. Intake of oat beta-glucans is associated with reductions in blood pressure and cholesterol levels, which in turn lowers the risk of cardiovascular disease (CVD). Beta-glucans are a soluble dietary fiber, which ferments in the colon and aids with carbohydrate and lipid metabolism. Beta-glucans also have potential cytotoxic properties.9 Rolled oats contain approximately 4% beta-glucan.2

Oat also contains avenanthramides, antioxidant phenolic compounds that were first identified in oat. Avenanthramides have been shown to exhibit anti-inflammatory, antiproliferative, and anti-itching activities, which correlates to oat’s traditional uses for skin care and gut health. Avenanthramides also have potential cancer preventive activities and may help with degenerative conditions such as atherosclerosis and osteoporosis.11

Table 1. Compounds Found in Oat Groats2,12,13

Compound Type

Compounds

Activities

Polysaccharides

Arabinoxylan, beta-glucans

Anti-inflammatory, blood glucose regulation, cytotoxic

Polyphenols

Apigenin, kaempferol, luteolin, quercetin 3-O-rutinoside, sinapoylquinic acid

Aids glucose and lipid metabolism, antimicrobial, antioxidant, neuroprotective

Tocols

Alpha-tocopherol

Antioxidant

 

Modern Research and Potential Health Benefits

Much of the current literature on oat focuses on oat-derived beta-glucans, though extracts of green oat have also been investigated based on their traditional uses. Clinical trials have become more prevalent, though most are small. More robust studies are needed to confirm the benefits of oat and its constituents.

Antimicrobial Activity

Oat extract exhibited a high degree of antifungal activity against Penicillium roqueforti, a common contaminant in commercial foodMature, brown oat pods on yellowed stems processing, and is safe to use directly on the surface of food to prevent colony formation.14 This antifungal activity is attributed to the presence of class I chitinase in cereal grains; however, oat seed extract contains 10 times more of this compound compared to wheat, barely, and rye seed extracts. Ethanolic extracts of oat also showed activity against gram positive and negative bacteria and fungal strains such as Candida albicans.

Cardiovascular Health

Numerous studies have been performed to observe the effects of oat consumption in a variety of forms, including oat-derived beta-glucans, on cardiovascular health markers including cholesterol levels, blood pressure measurements, endothelial function, and vasodilation. All these factors contribute to the development of CVD. Broadly, daily oat supplementation is associated with significant reductions in total cholesterol and low-density lipoprotein (LDL) cholesterol levels, and blood pressure, and enhanced production of nitric oxide, which can aid in the prevention of atherosclerosis.2,15-17 These results were observed in healthy adults as well as adults who had mild to moderate hypertension. Dose, length of intervention, and disease severity impacted outcomes, suggesting that daily supplementation over a long period of time would produce the most encouraging results.15 Oat consumption has also been correlated with a greater reduction in body mass of overweight adults compared to placebo; these participants also showed improvements in hepatic function.2 A dose of 3–3.5 grams of beta-glucans is considered the active dose.

Cognition and Mood

Animal studies have correlated green oat extract with enhancements in stress response and the activity of certain brain enzymes associated with mental health and behavior. Preclinical studies have also confirmed that oat interacts with neurotransmitters associated with cognition, memory, and motivation. In humans, both green and dried oat showed antidepressant and antianxiety activity, especially in participants with menopause, and a large dose of oat extract improved attention and concentration in older adults.2

Based on this history of use and documented evidence, some companies have developed proprietary green oat extracts and conducted clinical trials on their efficacy. One such extract, Neuravena® (Frutarom; Haifa, Israel), was tested on a small group of healthy adults. Compared to placebo, acute Neuravena supplementation was associated with superior performance and less mental tiredness.18 A different green oat extract, cognitaven® (Anklam Extrakt GmbH; Anklam, Germany), found that both acute and chronic supplementation was associated, in a dose-dependent manner, with significantly improved performance on a working memory task and a multitasking task in comparison to placebo.20

A text on the use of oat for opium addiction, 1882

Dermatology

Studies on the topical use of oat and oat extracts have shown that oat preparations are useful in treating inflammatory conditions including acne, atopic dermatitis (or atopic eczema), and pruritis (itchy skin). Oatmeal preparations also showed mild protection against ultraviolet rays. Oat extract containing avenanthramides exhibited antihistamine and anti-inflammatory activities on the skin.2

Smoking Cessation and Addiction

Oat has a traditional history of use for both assisting with overcoming addiction and easing symptoms of withdrawal. Oat extract was found to improve opioid and tobacco withdrawal symptoms in animal studies.2,20 However, there have been few studies investigating this use in humans and the results are mixed. In open, uncontrolled studies, participants who used opium showed a varied response to supplementation with green oat extract, with some ceasing use entirely and some maintaining their current habit; in a study of participants who smoked cigarettes, a slight trend toward smoking cessation was noted, with a stronger effect seen in light smokers than for heavy smokers.2

Consumer Considerations

Oats are widely cultivated on a global commercial scale and are not considered threatened. Wild species of oat, including A. fatua and A. sterilis, are listed under the category of “Least Concern” according to the IUCN Red List.21,22

Oats are a popular source of fiber and carbohydrates for those who are gluten-intolerant. Though oats do not naturally contain gluten, many commercially available brands are processed in factories where cross-contamination may be present. Consumers with gluten intolerances should look for brands of oats that are specifically labeled “gluten-free” to ensure this.

Nutrient Profile23
Per 100 grams of oats

Macronutrient Profile:

389 calories
16.9 g protein
66.3 g carbohydrate
6.9 g fat

Secondary Metabolites:

Excellent source of:

Manganese: 4.92 mg (213.9% DV)
Copper: 630 mcg (70% DV)
Thiamin (Vitamin B1): 0.77 mg (64.2% DV)
Magnesium: 177 mg (42.1% DV)
Phosphorus: 523 mg (41.8% DV)
Dietary Fiber: 10.6 g (35.3% DV)
Pantothenic acid (Vitamin B5): 1.35 mg (27% DV)
Iron: 4.72 mg (26.2% DV)

Very good source of:

Folate (Vitamin B9): 56 mcg (14% DV)
Riboflavin (Vitamin B2): 0.14 mg (10.8% DV)

Good source of:

Potassium: 429 mg (9% DV)
Vitamin B6: 0.12 mg (7% DV)
Niacin (Vitamin B3): 0.96 mg (6% DV)

Also provides:

Vitamin E: 0.7 mg (4.7% DV)
Calcium: 54 mg (4.2% DV)

DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000-calorie diet.

 

Recipe: Molasses-Tahini Granola
From Rise and Run24

Ingredients:

  • 3 1/2 cups rolled oats
  • 1 cup raw mixed nuts, chopped (almonds, cashews25, Brazil nuts26, walnuts, pecans27)
  • 1/2 cup raw sunflower or pumpkin28 seeds
  • 1/4 cup raw sesame29 seeds
  • 2 teaspoons ground cinnamon
  • 1 teaspoon ground ginger30 or cardamom
  • 1 teaspoon fine sea salt
  • 1/4 cup tahini
  • 1/4 cup extra-virgin olive oil
  • 1/4 cup blackstrap molasses
  • 1/4 cup honey

Directions:

  1. Heat the oven to 275°F. Line a rimmed baking sheet with parchment paper.
  2. In a large bowl, stir together the oats, nuts, seeds, cinnamon, ginger, and salt.
  3. In a small bowl, combine the tahini, olive oil, molasses, and honey. Stir thoroughly until smooth. Add the wet ingredients to the dry ingredients and mix well. The mixture will seem dry at first.
  4. Spread the mixture over the prepared baking sheet. Bake for 20 minutes, stir, and bake for 20 minutes more. The granola will still be moist and have a dark color at the end of baking. Cool completely before breaking into clusters and storing.
  5. Store in a lidded glass jar at room temperature. The granola will stay fresh for several weeks.

 

Image Credits:

All photos: Avena sativa ©2022 Steven Foster Group
Botanical Illustration: from Medicinal Plants by Robert Bentley and Henry Trimen; 1880.
Paper: The Opium Habit; Its Successful Treatment by the Avena Sativa by EHM Sell, MD. Presented February 9, 1882.

References

  1. American Botanical Council website. Available at: www.herbalgram.org/resources/healthy-ingredients/oat/. Accessed June 2, 2022.
  2. Al-Snafi AE. The nutritional and therapeutic importance of Avena sativa — an overview. International Journal of Phytotherapy. 2015;5(1):48-56.
  3. Alaoui SB. Avena sativa. Ecoport Project. June 3, 2017. Available at: http://ecoport.org/ep?Plant=481&entityType=PL****&entityDisplayCategory=full. Accessed July 11, 2022.
  4. Pacheco L. Oats (Avena sativa). HerbRally website. Available at: www.herbrally.com/monographs/oats. Accessed July 11, 2022.
  5. Ellingwood F, Lloyd JU. American Materia Medica, Therapeutics and Pharmacognosy. Chicago, IL: Ellingwood’s Therapeutist; 1915.
  6. Parvizi MM, Salami MH, Jazani AM, Javaheri R, Jaladat AM, Handjani F. Complementary and integrative remedies in the treatment of chronic pruritus: A review of clinical trials. J Cosmet Dermatol. May 2022. In press. Available at: https://onlinelibrary.wiley.com/doi/10.1111/jocd.15094. Accessed July 12, 2022.
  7. Sher H, Aldosari A, Ali A, de Boer HJ. Indigenous knowledge of folk medicines among tribal minorities in Khyber Pakhtunkhwa, northwestern Pakistan. J Ethnopharmacol. 2015;166:157-167.
  8. Bao-Luo M, Zheng Z, Ren C. Oat. In: Sadras VO, Calderini DF, eds. Crop Physiology Case Histories for Major Crops. New York, NY: Academic Press; 2021:222-248.
  9. Ciudad-Mulero M, Fernández-Ruiz V, Matallana-González MC, Morales P. Dietary fiber sources and human benefits: The case study of cereal and pseudocereals. Advances in Food and Nutrition Research. 2019;90:83-134.
  10. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific opinion on the substantiation of a health claim related to oat beta glucan and lowering blood cholesterol and reduced risk of (coronary) heart disease pursuant to Article 14 of Regulation (EC) No 1924/2006. EFSA Journal. 2010 Dec;8(12):1885.
  11. Yu Y, Zhou L, Li X, et all. The progress of nomenclature, structure, metabolism, and bioactivities of oat novel phytochemical: Avenanthramides. J Agric Food Chem. 2022 Jan;70(2):446-457.
  12. Dapčević-Hadnađev T, Hadnađev M, Pojić. The Healthy Components of Cereal By-Products and Their Functional Properties. In: Galanakis CM, ed. Sustainable Recovery and Reutilization of Cereal Processing By-Products. Cambridge, UK: Woodhead Publishing; 2018:27-61.
  13. Aparicio-Fernández X, Reynoso-Camacho R, Ramos-Gómez M, Mendoza-Sánchez M, Mora O, Pérez-Ramírez IF. Polyphenols and avenanthramides extracted from oat (Avena sativa) grains and sprouts modulate genes involved in glucose and lipid metabolisms in 3T3 L1 adipocytes. J Food Biochem. 2021 June;45(6):e13738.
  14. Sørensen HP, Madsen LS, Petersen J, Andersen JT, Hansen AM, Beck HC. Oat (Avena sativa) seed extract as an antifungal food preservative through the catalytic activity of a highly abundant class I chitinase. Appl Biochem Biotechnol. 2010 Mar;160(6):1573-1584.
  15. Yu J, Xia J, Yang C, et al. Effects of oat beta-glucan intake on lipid profiles in hypercholesterolemic adults: A systematic review and meta-analysis of randomized controlled trials. Nutrients. 2022 May;14(10):2043.
  16. Ho HVT, Sievenpiper JL, Zurbau A, et al. The effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: A systematic review and meta-analysis of randomised-controlled trials. Br J Nutr. 2016 Oct;116(8):1369-1382.
  17. Othman RA, Moghadasian MH, Jones PJ. Cholesterol-lowering effects of oat β-glucan. Nutr Rev. 2011 June;69(6):299-309.
  18. Martinez-Horta S, Ivanir E, Perrinjaquet-Moccetti T, Keuter MH, Kulisevsky J. Effects of a green oat herb extract on cognitive performance and neurophysiological activity: A randomized double-blind placebo-controlled study. Front Neurosci. 2021;15:748188.
  19. Kennedy DO, Bonnländer B, Lang SC, et al. Acute and chronic effects of green oat (Avena sativa) extract on cognitive function and mood during a laboratory stressor in healthy adults: A randomised, double-blind, placebo-controlled study in healthy humans. Nutrients. 2020 May;12(6):1598.
  20. Ebrahimie M, Bahmani M, Shirzad H, Rafieian-Kopaei M, Saki K. A review study on the effect of Iranian herbal medicines on opioid withdrawal syndrome. J Evid Based Complementary Altern Med. 2015 Oct; 20(4):302-309.
  21. Rhodes L, Bradley I, Zair W, Maxted N. Avena fatua. The IUCN Red List of Threatened Species. 2016:e.T172049A19394581. Available at: https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T172049A19394581.en. Accessed July 14, 2022.
  22. Rhodes L, Bradley I, Zair W, Maxted N. Avena sterilis. The IUCN Red List of Threatened Species. 2016:e.T172204A19395364. Available at: https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T172204A19395364.en. Accessed July 14, 2022.
  23. Oats (including foods for USDA’s Food Distribution Program). FoodData Central. United States Department of Agriculture Agricultural Research Service website. Available at: https://fdc.nal.usda.gov/fdc-app.html#/food-details/169705/nutrients. Accessed July 14, 2022.
  24. Flanagan S, Kopecky E. Rise and Run: Recipes, Rituals, and Runs to Fuel Your Day. New York, NY: Rodale; 2021.
  25. Perez J. Food as Medicine: Cashew (Anacardium occidentale, Anacardiaceae). HerbalEGram. 2020;17(10). Available at: www.herbalgram.org/resources/herbalegram/volumes/volume-17/number-10-october-2020/food-as-medicine-cashew/food-as-medicine-cashew/. Accessed July 14, 2022.
  26. Bauman H, Moser J. Food as Medicine: Brazil Nuts (Bertholletia excelsa, Lecythidaceae). HerbalEGram. 2019;16(5). Available at: www.herbalgram.org/resources/herbalegram/volumes/volume-16/number-5-may/food-as-medicine-brazil-nut-bertholletia-excelsa-lecythidaceae/food-as-medicine/. Accessed July 14, 2022.
  27. Bauman H, Royer H. Food as Medicine: Pecan (Carya illinoinensis, Juglandaceae). HerbalEGram. 2017;14(11). Available at: www.herbalgram.org/resources/herbalegram/volumes/volume-14/number-11-november/food-as-medicine-pecan-carya-illinoinensis-juglandaceae/food-as-medicine-pecan/. Accessed July 14, 2022.
  28. Perez J. Food as Medicine Update: Pumpkin (Cucurbita pepo, Cucurbitaceae). HerbalEGram. 2019;16(10). Available at: www.herbalgram.org/resources/herbalegram/volumes/volume-16/number-10-october/food-as-medicine-update-pumpkin/food-as-medicine-update-pumpkin/. Accessed July 14, 2022.
  29. Bauman H, Carrigg L. Food as Medicine: Sesame (Sesamum indicum, Pedaliaceae). 2017;14(1). Available at: www.herbalgram.org/resources/herbalegram/volumes/volume-14/number-1-january/food-as-medicine-sesame/food-as-medicine-sesame/. Accessed July 14, 2022.
  30. Bauman H, Hill K. Food as Medicine: Ginger (Zingiber officinale, Zingiberaceae). HerbalEGram. 2015;12(3). Available at: www.herbalgram.org/resources/herbalegram/volumes/volume-12/number-3-march/food-as-medicine-ginger-zingiber-officinale-zingiberaceae/food-as-medicine-ginger/. Accessed July 14, 2022.
References