**2. High antioxidant grains**

generally categorized as phenolic acids, flavonoids, stilbenes, coumarines and tannins [4]. The most abundant phenolic compounds found in whole grains are phenolic acids and flavonoids

**Wheat Rye Barley Corn Oats Rice Buckwheat Millet Sorghum**

Phosphorus 1170 3010 2460 990 4110 1030 1550 2400 350 Potassium 1550 4380 3290 1200 4000 1500 2420 2200 240 Magnesium 250 930 670 470 1170 350 1010 1000 188 Calcium 170 330 270 60 530 60 110 100 27 Sodium 20 50 40 10 40 20 10 NA 5 Zinc 8 28 13 5 30 17 25 34 3 Iron 12 28 24 11 38 12 15 48 11 Manganese 5 22 13 NA 58 9 15 7 1 Copper 1 3 1 NA 2 2 6 5 0.2

According to the FDA, a whole grain food is said to meet the whole grain health claim when it contains 51% whole grain flour by weight of its final product. It is also said to meet the whole grain health claims when it contains all components of the intact grain, has about 1.7 g of dietary fibre and also contains 16 g whole grain per serving [5]. *In vitro* minerals (Table 1) and phytochemicals in grains can act as antioxidants and used as nutraceuticals when consumed, by providing the body with protection against cardiovascular, anticancer, antidiabetics and

(Figure 1).

**Figure 1.** Structures of common phenolic compounds

168 Antioxidant-Antidiabetic Agents and Human Health

**Minerals mg/kg Whole grains**

NA not available. Source: [8,9].

**Table 1.** Mineral content of whole grains

Whole cereal grains contain a wide range of bioactive components with antioxidant effect [10] such as dietary fibre (DF) and phytochemicals [11,12] that are beneficial against diabetes, colon cancer and cardiovascular disease (CVD) [13,6,14]. Antioxidants present in whole grain cereals act in defense to remove the reactive oxygen species (ROS) thereby preventing and curing oxidative stress-related diseases. In [15], it was reported that vitamin E, folates, polyphenols, minerals, trace elements, carotenoids, phytic acid, lignin and alkylresorcinols are the bioactive compounds available in cereal grains. Polyphenols that are predominant in cereals are hydroxycinnamic, ferulic, gallic, vanillic and ρ-coumaric acids, of which, ferulic acid is the most potent. Phenolic compounds [16] are said to be present in cereal grains in free and bound form, as conjugates with sugars, fatty acids or as proteins. These polyphenols have several biological functions such as antioxidant, anti-inflammatory and anti-cancer activities that can protect the human body, which is constantly exposed to endogenous and exogenous free radicals [17]. Plant sterols, also called phytosterols, found in plants, have been clinically shown to lower low-density lipoprotein (LDL) cholesterol by about 8 to 15% as part of a heart-healthy diet. Also, wholegrains that serve as source of DF are useful in the prevention and treatment of constipation, CVD and hypertension [8,12].

Grains can be classified as typical and pseudo-cereals. Typical cereals include sorghum, wheat, rice, barley, millet, rye, oat, maize, buckwheat, triticale, fonio, canary grass. Pseudo-cereals include amaranth, buckwheat, quinoa, kaniwa, and pitseed. Cereals reported with high antioxidant capacity include sorghum, wheat, barley, millet and amaranth. It has also been reported that bioactive substances occur in grains at different concentrations and identities depending on genotypes and phenotypes [9]. Sorghum, millet and barley adapted to the UAE environment, were found to contain reasonable levels of DF and antioxidant properties [9]. Experimental evidence has shown that certain cereals such as sorghum are rich in antioxidants that are comparable to those in fruits and vegetables [19]. Varieties of sorghum such as black sorghum, have been shown to contain significant amount of antioxidants; condensed tannins, anthocyanins (Figure 2 and 3) and other phytochemicals with properties that complement the phytochemicals present in fruits and vegetables [19]. Whole wheat and wheat bran-based ready-to-eat breakfast cereals have also been reported to be an important source of dietary antioxidants [20]. It has been shown [21] that buckwheat constitutes high amount of total phenolics, with the highest DPPH radical scavenging activity and capacity for Fe3+ reduction. Phenolic acids from breakfast cereals exhibit strong antioxidant activity *in vitro* at concentra‐ tions that can be obtained from a normal serving of whole wheat cereal [20]. Available data from the literature also reveals that sorghum is a significant source of phytosterols (tocopherols, tocotrienols) and policosanol, while rice has been shown to be rich in oryzanols [22].

tissues against oxidative reactions through its ability to sequester and inactivate pro-oxidative transition metals [25,20]. In addition, acid conditions and enzymic hydrolysis has been reported to increase the solubility and activity of wheat phenolics, suggesting that the digestive process could be important in altering the antioxidant potential of wheat-based foods [20]. Simulated gastrointestinal pH treatment and enzymatic hydrolysis also increase the antioxi‐ dant activity of wheat and wheat-based breakfast cereal extracts, suggesting that the digestive process could be important in further enhancing the antioxidant potential of wheat-based foods [20]. However, it is still unclear if the consumption of cereal causes better health or

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Processed products from cereals contain different antioxidant contents at varying amounts (Table 2). The cereals containing most antioxidants include barley, millet, maize and oats. Notably, polished rice and refined wheat, which are the main cereals eaten by humans globally are among the cereals with the lowest content of antioxidants [28]. In contrast, common millet and sorghum, which are important in particular regions in sub-Saharan Africa, South America and Asia, contains medium to high concentrations of antioxidants. The predominant types of antioxidants in corn are ferulic acid, anthocyanins, catechin and ρ-caomaric acid. Wheat is high in β-glucan, β-cryptoxanthin, catechins, lutein, zeaxanthin and phytosterols. Barley is rich in tocopherols, tocotrienols and ferulic acids. Millet is high in tricin, luteolin and serotonin, whilst buckwheat contains rutin and catechins. Oats and rice are rich in avertramidin, catechins,

In the case of whole grains, corn, wheat, rice and oats are regarded as grains with high antioxidant activities. Corn has the highest total antioxidant activity compared to the other three grain types, followed by wheat and then oats. Rice has the lowest antioxidant activity compared to corn, wheat and oats [29]. Corn shows the highest total phenolic content at 1560 ± 60 μmol gallic acid equivalents/100 g, followed by wheat at 800 ± 40 μmol gallic acid equivalents/100 g, oats at 650 ± 20 μmol gallic acid equivalents/100 g and rice at 560 ± 20 μmol gallic acid equivalents/100 g. A study designed to investigate the complete phytochemical profiles in free, soluble conjugated, and insoluble bound forms, as well as their antioxidant activities in uncooked whole grains [30] showed that corn had the highest total antioxidant activity (181.42 ± 0.86 μmol of vitamin C equivalent/g of grain), followed by wheat (76.70 ± 1.38 μmol of vitamin C equivalent/g of grain), oats (74.67 ± 1.49 μmol of vitamin C equivalent/ g of grain), and rice (55.77 ± 1.62 μmol of vitamin C equivalent/g of grain). Bound phytochem‐ icals were the major contributors to the total antioxidant activity; 90% in wheat, 87% in corn, 71% in rice and 58% in oats. Bound phytochemicals can survive stomach and intestinal digestion to reach the colon. This may partly explain the mechanism of grain consumption in the prevention of colon cancer, other digestive cancers, breast cancer and prostate cancer as supported by epidemiological studies. Antioxidant activity of methanolic extracts from some grains consumed in Korea [31] revealed that the methanolic extracts prepared from red sorghum and black rice showed significantly higher antioxidant activities and contained higher polyphenolic contents than other grains such as white rice, brown rice, mungbean, foxtail millet, prosomillet, barley and adlay. Polyphenolic compounds were found to be the major naturally occurring antioxidants in grains. Antioxidant activity of small grain cereals

whether it is a case of health status influencing food choice [26,27,23].

proanthocyanidins and anthocyanins [3].

**Figure 2.** Condensed tannin

**Figure 3.** Chemical structure of anthocyanin

Cereals naturally contain a wide variety of polyphenols such as the hydroxycinnamic, ferulic, vanillic, and ρ-coumaric acids [20], which show a strong antioxidant power and may help to protect oxidative stress thus decreasing the risk of contracting several diseases [23,24]. Whole grains including wheat, contains several essential compounds that impact on the oxidative stability of cells. These compounds include selenium, β-carotene, vitamins C and E, phytate, proteins, polysaccharides, phenolics, lignans and tocopherols [20]. Phytic acid can protect tissues against oxidative reactions through its ability to sequester and inactivate pro-oxidative transition metals [25,20]. In addition, acid conditions and enzymic hydrolysis has been reported to increase the solubility and activity of wheat phenolics, suggesting that the digestive process could be important in altering the antioxidant potential of wheat-based foods [20]. Simulated gastrointestinal pH treatment and enzymatic hydrolysis also increase the antioxi‐ dant activity of wheat and wheat-based breakfast cereal extracts, suggesting that the digestive process could be important in further enhancing the antioxidant potential of wheat-based foods [20]. However, it is still unclear if the consumption of cereal causes better health or whether it is a case of health status influencing food choice [26,27,23].

from the literature also reveals that sorghum is a significant source of phytosterols (tocopherols,

Cereals naturally contain a wide variety of polyphenols such as the hydroxycinnamic, ferulic, vanillic, and ρ-coumaric acids [20], which show a strong antioxidant power and may help to protect oxidative stress thus decreasing the risk of contracting several diseases [23,24]. Whole grains including wheat, contains several essential compounds that impact on the oxidative stability of cells. These compounds include selenium, β-carotene, vitamins C and E, phytate, proteins, polysaccharides, phenolics, lignans and tocopherols [20]. Phytic acid can protect

tocotrienols) and policosanol, while rice has been shown to be rich in oryzanols [22].

**Figure 2.** Condensed tannin

170 Antioxidant-Antidiabetic Agents and Human Health

**Figure 3.** Chemical structure of anthocyanin

Processed products from cereals contain different antioxidant contents at varying amounts (Table 2). The cereals containing most antioxidants include barley, millet, maize and oats. Notably, polished rice and refined wheat, which are the main cereals eaten by humans globally are among the cereals with the lowest content of antioxidants [28]. In contrast, common millet and sorghum, which are important in particular regions in sub-Saharan Africa, South America and Asia, contains medium to high concentrations of antioxidants. The predominant types of antioxidants in corn are ferulic acid, anthocyanins, catechin and ρ-caomaric acid. Wheat is high in β-glucan, β-cryptoxanthin, catechins, lutein, zeaxanthin and phytosterols. Barley is rich in tocopherols, tocotrienols and ferulic acids. Millet is high in tricin, luteolin and serotonin, whilst buckwheat contains rutin and catechins. Oats and rice are rich in avertramidin, catechins, proanthocyanidins and anthocyanins [3].

In the case of whole grains, corn, wheat, rice and oats are regarded as grains with high antioxidant activities. Corn has the highest total antioxidant activity compared to the other three grain types, followed by wheat and then oats. Rice has the lowest antioxidant activity compared to corn, wheat and oats [29]. Corn shows the highest total phenolic content at 1560 ± 60 μmol gallic acid equivalents/100 g, followed by wheat at 800 ± 40 μmol gallic acid equivalents/100 g, oats at 650 ± 20 μmol gallic acid equivalents/100 g and rice at 560 ± 20 μmol gallic acid equivalents/100 g. A study designed to investigate the complete phytochemical profiles in free, soluble conjugated, and insoluble bound forms, as well as their antioxidant activities in uncooked whole grains [30] showed that corn had the highest total antioxidant activity (181.42 ± 0.86 μmol of vitamin C equivalent/g of grain), followed by wheat (76.70 ± 1.38 μmol of vitamin C equivalent/g of grain), oats (74.67 ± 1.49 μmol of vitamin C equivalent/ g of grain), and rice (55.77 ± 1.62 μmol of vitamin C equivalent/g of grain). Bound phytochem‐ icals were the major contributors to the total antioxidant activity; 90% in wheat, 87% in corn, 71% in rice and 58% in oats. Bound phytochemicals can survive stomach and intestinal digestion to reach the colon. This may partly explain the mechanism of grain consumption in the prevention of colon cancer, other digestive cancers, breast cancer and prostate cancer as supported by epidemiological studies. Antioxidant activity of methanolic extracts from some grains consumed in Korea [31] revealed that the methanolic extracts prepared from red sorghum and black rice showed significantly higher antioxidant activities and contained higher polyphenolic contents than other grains such as white rice, brown rice, mungbean, foxtail millet, prosomillet, barley and adlay. Polyphenolic compounds were found to be the major naturally occurring antioxidants in grains. Antioxidant activity of small grain cereals


pound present in the wheat and rye fractions was ferulic acid but small quantities of diferulic acids, sinapic acid, ρ-coumaric acid and benzoic acid derivatives were also present. The largest proportions of these phenolic compounds were found as covalently bound (esters) in the insoluble pellet but between 10% and 30% of the total compounds were solubilized, mostly in water. Most of the antioxidant capacity was found in the water extracts from all the cereal fractions. Overall, buckwheat and wheat germ products exhibited the highest antioxidant capacity whereas the rye products had the lowest antioxidant values, an indication that the consumption of buckwheat and wheat germ could be an important source of antioxidants

**Grains Tocopherols Tocotrienols**

Wheat 10 7 NA NA 4 28 NA NA Rye 16 4 NA NA 15 8 NA NA Barley 8.6 0.9 5.6 0.7 40.3 8.7 10.4 0.9 Oats 14.9 3.0 0.4 NA 56.4 5.4 NA NA Maize 3.7 0.2 45.0 1.0 5.3 NA 11.3 0.4 Rice 14.6 1.0 1.3 0.1 8.7 NA 11.9 0.5

**α β γ δ α β γ δ**

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The phytochemical content and antioxidant activity of six diverse varieties of whole wheat as reported in [34] showed free phenolic content ranging from 255 (KanQueen) to 499 (Roane) 1mol gallic acid equivalents/100 g DW. The bound phenolic content ranged from 582 (Roane) to 662 (Cham1) 1mol gallic acid equivalents/100 g DW. The bound fraction contributed 53.8 - 69.7% of the total phenolic content of the wheat varieties analysed. Ferulic acid was the predominant phenolic acid found in whole wheat. Total ferulic acid content ranged from 310.8 (Caledonia) to 496.1 (KanQueen) 1mol ferulic acid/100 g DW. The percentage of ferulic acid found in the insoluble-bound fraction ranged from 87.4% (Caledonia) to 97.2% (KanQueen). Other phenolic acids, ρ-coumaric acid, syringic acid, vanillic acid, and caffeic acid were also detected. Lutein was the predominant carotenoid found in the whole wheat varieties ana‐ lysed. Zeaxanthin, β-carotene, and β-cryptoxanthin were also detected. Mainly α- and βtocopherols and α- and β-tocotrienols were found in all varieties of whole wheat though δtocopherol was detected in all but two varieties. β-tocotrienol was the predominant form of vitamin E found in all varieties of whole wheat (Table 3). The antioxidant activity was as‐ sessed using the oxygen radical absorbance capacity (ORAC) assay. The ORAC of the free fraction ranged from 1958 to 3749 1mol Trolox equivalents/100 g DW. The ORAC of the bound fraction ranged from 3190 to 5945 1mol Trolox equivalents/100 g DW. Total phenolic content

phytochemicals found in whole grains may be responsible for the health benefit derived from

= 0.810; p < 0.001). They concluded that

required for healthy living.

NA = not available. Source: [35-37].

**Table 3.** Vitamin E content of whole grains flour mg/kg dry matter

whole grain consumption.

correlated with oxygen radical absorbance capacity (R2

**Table 2.** Total antioxidant concentration of cereals.

caused by phenolics and lipid soluble antioxidants as investigated in [32] showed a general considerable variation in antioxidant activities and phytochemical contents between cereals. A higher DPPH radical scavenging ability and reducing power were detected in hull-less barley, followed by rye and hull-less oat and durum and bread wheat, indicating that small grain species have different major antioxidants with different properties. Hull-less barley was found to have the highest content of total free phenols, flavonoids, PVPP bound phenolics and contained flavan-3-ols, not found in other species. Hull-less oat had the highest content of tocopherols, very high content of yellow pigments and PVPP bound phenolics. Ferulic acid was the major free phenolic acid in small grain cereals tested. A study designed to determine the composition in hydroxycinnamic acids and the antioxidant properties of soluble extracts from wheat, rye and buckwheat [33] revealed that the highest levels of total hydroxycinnamic acids and derivatives were found in the wheat bran and rye bran fractions whereas the buckwheat flours had only trace quantities of these compounds. The most abundant com‐


**Table 3.** Vitamin E content of whole grains flour mg/kg dry matter

caused by phenolics and lipid soluble antioxidants as investigated in [32] showed a general considerable variation in antioxidant activities and phytochemical contents between cereals. A higher DPPH radical scavenging ability and reducing power were detected in hull-less barley, followed by rye and hull-less oat and durum and bread wheat, indicating that small grain species have different major antioxidants with different properties. Hull-less barley was found to have the highest content of total free phenols, flavonoids, PVPP bound phenolics and contained flavan-3-ols, not found in other species. Hull-less oat had the highest content of tocopherols, very high content of yellow pigments and PVPP bound phenolics. Ferulic acid was the major free phenolic acid in small grain cereals tested. A study designed to determine the composition in hydroxycinnamic acids and the antioxidant properties of soluble extracts from wheat, rye and buckwheat [33] revealed that the highest levels of total hydroxycinnamic acids and derivatives were found in the wheat bran and rye bran fractions whereas the buckwheat flours had only trace quantities of these compounds. The most abundant com‐

**Cereals Botanical name Family Amount present in cereals**

Barley, whole meal flour *Hordeum vulgare Poaceae* 1.09 Common millet, wholemeal flour *Pennisetum glaucum Poaceae* 0.82 Maize, white flour *Zea mays Poaceae* 0.62 Oats, rough oatmeal *Avena sativa Poaceae* 0.59 Barley, white flour *Hordeum vulgare Poaceae* 0.58 Rye, wholemeal flour *Secale cereal Poaceae* 0.47 Wheat, wholemeal flour *Triticum aestivum Poaceae* 0.33 Oats, white flour *Avena sativa Poaceae* 0.32 Bulgur wheat, wholemeal flour *Triticum aestivum Poaceae* 0.31 Sorghum, wholemeal flour *Sorgum bicolor Poaceae* 0.30 Common millet, white flour *Pennisetum glaucum Poaceae* 0.25 Rye, white flour *Secale cereal Poaceae* 0.23 Rice, grains *Oryza sativa Poaceae* 0.17 Wheat, white flour *Triticum aestivum Poaceae* 0.13 Durum wheat, white flour *Triticum durum Poaceae* 0.05 Rice, white flour *Oryza sativa Poaceae* 0.04

Buckwheat, wholemeal flour *Fagopyrum esculentum Polygonaceae* 1.99 Buckwheat, white flour *Fagopyrum esculentum Polygonaceae* 1.23

Pseudo-cereals

Adapted from [28].

**Table 2.** Total antioxidant concentration of cereals.

172 Antioxidant-Antidiabetic Agents and Human Health

**mmol/100 g**

pound present in the wheat and rye fractions was ferulic acid but small quantities of diferulic acids, sinapic acid, ρ-coumaric acid and benzoic acid derivatives were also present. The largest proportions of these phenolic compounds were found as covalently bound (esters) in the insoluble pellet but between 10% and 30% of the total compounds were solubilized, mostly in water. Most of the antioxidant capacity was found in the water extracts from all the cereal fractions. Overall, buckwheat and wheat germ products exhibited the highest antioxidant capacity whereas the rye products had the lowest antioxidant values, an indication that the consumption of buckwheat and wheat germ could be an important source of antioxidants required for healthy living.

The phytochemical content and antioxidant activity of six diverse varieties of whole wheat as reported in [34] showed free phenolic content ranging from 255 (KanQueen) to 499 (Roane) 1mol gallic acid equivalents/100 g DW. The bound phenolic content ranged from 582 (Roane) to 662 (Cham1) 1mol gallic acid equivalents/100 g DW. The bound fraction contributed 53.8 - 69.7% of the total phenolic content of the wheat varieties analysed. Ferulic acid was the predominant phenolic acid found in whole wheat. Total ferulic acid content ranged from 310.8 (Caledonia) to 496.1 (KanQueen) 1mol ferulic acid/100 g DW. The percentage of ferulic acid found in the insoluble-bound fraction ranged from 87.4% (Caledonia) to 97.2% (KanQueen). Other phenolic acids, ρ-coumaric acid, syringic acid, vanillic acid, and caffeic acid were also detected. Lutein was the predominant carotenoid found in the whole wheat varieties ana‐ lysed. Zeaxanthin, β-carotene, and β-cryptoxanthin were also detected. Mainly α- and βtocopherols and α- and β-tocotrienols were found in all varieties of whole wheat though δtocopherol was detected in all but two varieties. β-tocotrienol was the predominant form of vitamin E found in all varieties of whole wheat (Table 3). The antioxidant activity was as‐ sessed using the oxygen radical absorbance capacity (ORAC) assay. The ORAC of the free fraction ranged from 1958 to 3749 1mol Trolox equivalents/100 g DW. The ORAC of the bound fraction ranged from 3190 to 5945 1mol Trolox equivalents/100 g DW. Total phenolic content correlated with oxygen radical absorbance capacity (R2 = 0.810; p < 0.001). They concluded that phytochemicals found in whole grains may be responsible for the health benefit derived from whole grain consumption.

Rice is rich in phytochemicals that are present in lipophilic, hydrophilic and insoluble forms. In reference [38], it was indicated that tocopherols, tocotrienols (Figure 4) and ץ-oryzanol, are major lipophilic fractions of whole grain rice and are beneficial to human health. It also contains tricin, ferulic acid, caffeic acid and methoxycinnamic acid which are hydrophilic phenolic compounds reported to have cancer protective potential. Barley grains contain DFs, β-glucans, arabinoxylans and polyphenols [39,40]. β-glucans and arabinoxylans present in barley are critical nutrients that determine wort viscosity, foam stability and beer filtration rates, thus playing a significant role in beer brewing process [41,42]. Barley β-glucans also plays health beneficial roles in the reduction of blood cholesterol level, glucose level and helps in weight loss by increasing satiety, thereby reducing susceptibility to heart disease and type-2 diabetes [40]. Oats and psyllium husk which contains fibres have also been implicated in the reduction of homocysteine, cholesterol and risk of CVD [43]. Millets are rich source of DF, phytochemi‐ cals, micronutrients, nutraceuticals, and could be rightly termed as nutricereals.

**3. Grains and human health**

Dietary antioxidants are food compounds that impede the deleterious effects of reactive oxygen species, reactive nitrogen species, or both, on the normal physiological function in humans [44,27]. Dietary antioxidants include ascorbate, tocopherols, carotenoids and bioactive plant phenols. ROS; oxygen ions, free radicals, and peroxides and reactive nitrogen species (RNS); nitrous anhydride, peroxynitrite, and nitrogen dioxide radicals, causes oxidation, nitration, halogenation and deamination of biomolecules of all types, including lipids, proteins, carbohydrates, and nucleic acids, with the resultant formation of toxic and mutagenic products [45,46]. Biological systems control these oxidative factors by a variety of antioxidative mechanisms that restrict the reactivity of ROS and RNS and oxidation catalysts [20]. In human cells, *de novo* antioxidant production is much more limited and oxidative damage resulting from excess production of free radicals has been reported to initiate the pathogenesis of most chronic degenerative diseases such as brain stroke, diabetes mellitus, rheumatoid arthritis, Parkinson's disease, Alzheimer's disease, and cancer [27,28]. The production of ROS and RNS are speedily formed in cells as a consequence of disease processes (e.g. inflammation), tobacco smoke, environmental pollutants, ingestion of oxidized foods, ischemia, drugs, ethanol and radiations. If unchecked, such cellular event can promote a chain of chemical reactions that form free radicals, peroxides and secondary oxidation breakdown products which in turn reacts with and cause damage to cellular membranes, proteins and nucleic acids [20,23].

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Phenolic compounds present in whole grains are known to be effective in protecting against CVDs and some cancer (Table 4). This protective effect is thought to be mediated through their action as antioxidants to prevent oxidative damage induced by ROS to some biomolecules (DNA, lipids and proteins) under pathological conditions [47]. In reference [48], it was reported that phenolic compounds could be responsible for chelating metals as well as inhibiting the free radicals capitation by limiting the action of the lipoxygenase enzyme. Phytate compounds on the other hand may exert antioxidant activity by complexing with iron, reducing the formation of free radicals and peroxidation of membranes, which could provide anticarcino‐ genic power. Lignans on their part are a group of dietary phytoestrogen found in a variety of plant foods like corn, oats, rye, wheat, flaxseeds, legumes, fruits and vegetables. These plant lignans when consumed are converted to the mammalian lignans, enterodiol and enterolac‐ tone which have strong antioxidant activity. β-glucan is mostly found in cell walls of oats, barley and wheat. Its major biological effects include lowering of blood cholesterol level, controlling blood sugar, promotion of weight management, encouraging the growth of beneficial gut microflora and enhancing the immune system. This is probably due to its high viscosity property as a soluble fibre to bind cholesterol and bile acids and facilitate their elimination from the body. It has been [93] indicated that β-glucan had an effect in controlling blood sugar in diabetes subjects, and was helpful in reducing the elevation in blood sugar levels after a meal. The authors further indicated that this is probably as a result of delaying gastric emptying, allowing dietary sugar to be absorbed more gradually, as well as by possibly increasing the tissue sensitivity to insulin. The United States Food and Drug Administration (FDA) is allowing whole grain barley products that can supply β-glucan at levels of 0.75 g per serving or 3 g per day to carry a claim that they reduce the risk of coronary heart disease [49].

**Figure 4.** Tocopherols and tocotrienols in grains
