1.Oats
Oat, which is the most produced after wheat and barley among the cool climate cereals in the world, has an important place in the diet and feed industry due to the nutrients it contains. Oats were cultivated in the 1st century AD and spread to the whole world from Europe in the 5th century. Especially in Seljuk and Ottoman periods, oats were used as bread grain in times of famine. Today, the usage areas in human nutrition (bread, biscuits, probiotic drinks, baby food and oat flakes thanks to its satiating feature) are diversifying and increasing day by day as a result of the acceleration of the demand for adequate and balanced nutrition in the eyes of the consumer [1]. However, the oat gluten relationship arouses curiosity.
1.1. Nutritional Composition of Oats
Oats come to the fore in the diet thanks to their protein quality, high unsaturated fat and fiber content, and antioxidant richness. It is recommended to be consumed as a whole grain, especially since there are vitamins and minerals in both the shell and the embryo of the oat grain.
- Among the cereals, the oil content in dry matter varies between 3-12% and the average oil content is reported as 6.9% (around 11% for husked oat grain) in oats containing the highest amount of oil per grain. Although the physicochemical properties of oat and wheat oil are similar, oats contain more unsaturated fatty acids, linoleic and oleic acids. In addition, although the oil content in other grains is found in the germ, it is spread throughout the whole grain in oats.
- The protein amount of oats can vary between 10-24% depending on the variety and environmental conditions. The World Health Organization (WHO) has reported that the quality of oat protein is equivalent to soy protein. Oats contain more lysine, an essential amino acid, compared to other cereals, and also contain amino acids isoleucine, leucine and arginine, which are essential for babies.
- Vitamins E and B are abundant in oats, while vitamins A, C and D are found in trace amounts.
- Oat grain is very rich in terms of phosphorus, iron, magnesium, calcium and selenium, which is involved in DNA regeneration in the body, and has a high nutritional value.
- Oat is one of the main sources of fiber since the husk is not physically separated from the grain and is generally consumed directly (whole grain). Oats, which have both soluble and insoluble fibers, contain soluble fibers in the form of β-glucan and insoluble fibers are in the form of arabinoxylan and cellulose [1].
1.2. Some Roles of Oats on Human Health and the Relationship between Oat and Gluten
- Oats have the highest content of avenanthramide among all grain groups. Avenanthramide, a phenolic antioxidant group, has shown that it may have anti-inflammatory and antidiabetic properties in some preliminary studies on the cardiovascular system. They also play a role in controlling blood pressure, as they produce nitric oxide, which dilates blood vessels.
- Soluble fiber β-glucans, which are abundant in oats, show immune system-supportive effects by binding to special surfaces on white blood cells, which are the first defense of the immune system. In addition, β-glucans, due to their sticky nature, have the ability to retain cholesterol and even acids in the blood, helping to remove these substances from the body. In this way, it lowers the blood cholesterol level and keeps the blood sugar in balance.
- When consumed with oats, vitamin C and E supplements, it lowers blood pressure and improves the endothelial layer [1].
2. Does Oats Contain Gluten?
In grains such as wheat, rye, barley and oats, most of the protein (about 80%) is gluten protein, which consists of a combination of two different fractions, gliadin and glutenin. Therefore, gluten-free foods should not contain wheat, barley, rye, and arguably oats [2]. Although many celiac patients consume oats, it cannot be said that oats are gluten-free according to current food regulations. These differences in toxicity are due to differences in the structure and amino acid sequence of different prolamins in different grains. For this reason, it has been suggested that oats may also be toxic for individuals with gluten sensitivity, since oats contain relatively low amounts of prolamin in the grain and oat prolamins are similar to wheat prolamins, even if slightly. Studies have shown that oat consumption of 50 g/day will not be toxic for celiac patients.
The amount of gluten in oat grains is lower compared to other grains. Although it is claimed that there is no negative effect on the intestinal mucosa when celiac patients consume oats and its derivatives, it has not been confirmed that gluten-sensitive people can definitely use oats in the USA. However, it is thought that it can be evaluated by limiting the amount of consumption (about half a glass of dry whole grain oatmeal per day). This may vary depending on the patient’s individual tolerance, nutritional dynamics and the course of the disease. Therefore, celiac patients should make this decision in the presence of their physician, taking into account the differences of opinion among experts [3].
In the United States and Canada, the gluten-free diet includes only foods that contain no gluten at all. On the contrary, wheat starch is allowed in products with gluten-free label in the UK. The gluten-free food standard of the Turkish Standards Institute is defined in two parts; In foods defined as “reduced gluten”, the gluten content should not be more than 200 mg/kg dry matter (DM). In “gluten-free” foods, the gluten content should not exceed 20 mg/kg DM [4].
In addition, it is possible for oats to be contaminated (contaminated) with wheat, barley and rye prolamins in the processes (harvesting, storage, milling, etc.) before they reach the consumer. Therefore, this possibility should be taken into account by people with gluten sensitivity who prefer oats.
Source
[1] Karaman, R., Akgün, İ., Türkay, C. (2020). Alternative Food Source in Human Nutrition: Oats. Turkish Journal of Science and Engineering, 2(2): 78-85.
[2] Doğu-Baykut, E. (2021). Nutritional Content and Use in Food Industry of Some Cereal-Like Products. European Journal of Science and Technology, 23: 89-98.
[3] Aide, E., Ertaş, N. (2013). Composition of Oats, Usage Areas in Grain Industry and Effects on Human Health. Journal of Food and Feed Science – Technology, 13:41-50.
[4] İşleroğlu, H., Dirim, S.N., Ertekin, F.K. (2009). Gluten-Free, Cereal-Based Alternative Product Formulations and Production Technologies. FOOD, 34(1): 29-36.
