Article

The potential role of phytochemicals in wholegrain cereals for the prevention of type-2 diabetes

Nutrition Journal (Impact Factor: 2.6). 05/2013; 12(1):62. DOI: 10.1186/1475-2891-12-62
Source: PubMed

ABSTRACT

Diets high in wholegrains are associated with a 20-30% reduction in risk of developing type-2 diabetes (T2D), which is attributed to a variety of wholegrain components, notably dietary fibre, vitamins, minerals and phytochemicals. Most phytochemicals function as antioxidants in vitro and have the potential to mitigate oxidative stress and inflammation which are implicated in the pathogenesis of T2D. In this review we compare the content and bioavailability of phytochemicals in wheat, barley, rice, rye and oat varieties and critically evaluate the evidence for wholegrain cereals and cereal fractions increasing plasma phytochemical concentrations and reducing oxidative stress and inflammation in humans. Phytochemical content varies considerably within and among the major cereal varieties. Differences in genetics and agro-climatic conditions explain much of the variation. For a number of the major phytochemicals, such as phenolics and flavanoids, their content in grains may be high but because these compounds are tightly bound to the cell wall matrix, their bioavailability is often limited. Clinical trials show that postprandial plasma phenolic concentrations are increased after consumption of wholegrain wheat or wheat bran however the magnitude of the response is usually modest and transient. Whether this is sufficient to bolster antioxidant defences and translates into improved health outcomes is still uncertain. Increased phytochemical bioavailability may be achieved through bio-processing of grains but the improvements so far are small and have not yet led to changes in clinical or physiological markers associated with reduced risk of T2D. Furthermore, the effect of wholegrain cereals and cereal fractions on biomarkers of oxidative stress or strengthening antioxidant defence in healthy individuals is generally small or nonexistent, whereas biomarkers of systemic inflammation tend to be reduced in people consuming high intakes of wholegrains. Future dietary intervention studies seeking to establish a direct role of phytochemicals in mediating the metabolic health benefits of wholegrains, and their potential for mitigating disease progression, should consider using varieties that deliver the highest possible levels of bioavailable phytochemicals in the context of whole foods and diets. Both postprandial and prolonged responses in systemic phytochemical concentrations and markers of inflammation and oxidative stress should be assessed along with changes related to health outcomes in healthy individuals as well as those with metabolic disease.

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Available from: Damien P Belobrajdic
    • "Eugenio Garza Sada 2501 On the other hand, it is known that a controlled postharvest abiotic stress can increase the synthesis of phytochemicals with health-promoting properties (Jacobo-Velázquez and others 2011; Guajardo-Flores and others 2014; Moses and others 2014). Most phytochemicals found in cereals and pulses have the potential to diminish oxidative stress, inflammation, and prevent different diseases like Type-2 diabetes (Belobrajdic and Bird 2013 ), coronary heart disease (Truswell 2002), or cancer (Guajardo-Flores and others 2013). Although selenium is not an essential nutrient for plants, this mineral has been used as a chemical stress technique during grain germination to increase Se-containing amino acids, which are considered as potent nutraceuticals (Lintschinger and others 2000). "
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    ABSTRACT: Pseudocereal Chenopodium berlandieri spp. (huauzontle) was evaluated to determine saponin composition. Saponins were evaluated in raw and germinated grains subjected to chemical stress induced by sodium selenite. Analysis by liquid chromatography coupled with ELSD detector revealed the presence of 12 saponins, identified according to compounds previously assayed in Chenopodium quinoa. Saponins found at the highest concentrations in raw grains were derived from oleanolic and phytolaccagenic acids. Total saponin concentration significantly decreased in germinated compared to raw grains due to the significant loss of 90.1% and 95.7% of the phytolaccagenic acid without and with chemical selenium stress, respectively. The most abundant saponin in germinated sprouts decreased during normal germination. Interestingly, the concentration of this particular saponin significantly increased during the Se-induced stress germination. Chemical stress with selenium salts proved to change the saponin composition in geminated Chenopodium berlandieri spp. grains, therefore affecting their potential use as ingredient in the food industry.
    No preview · Article · Dec 2015 · Journal of Food Science
    • "The Se associated with bread has been particularly well retained by various body tissues (Hart et al. 2011; Thiry et al. 2012). Subjects consuming brown or whole wheat bread containing high levels of Se increased blood GPx levels by 10% (Thomson et al. 1985, cited by Belobrajdic and Bird 2013). Health Implications of Consumption of Se-Enriched Breads. "
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    ABSTRACT: Bread is among the three top foods that provide most of the dietary selenium (Se) for most of the world population. Selenomethionine present in flour and bread is the major organic moiety (>65%). The Se concentration assayed in wheat kernels is mainly affected by agronomic factors such as soil fertility. The dry milling of wheat to produce refined flour and the technology to produce leavened breads also greatly affect Se concentration and bioavailability. The supranutritional intakes of inorganic and mainly organic Se have long been linked to the prevention of cancer, oxidative stress, and cardiovascular diseases. This review provides an overview of the different Se sources and agronomic, milling, and processing factors that affect Se concentration and bioavailability in yeast-leavened and sourdough breads and the nutritional and health implications that have been documented by food, medical, and nutrition scientists.
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    • "alkylresorcinols (AR), phenolic acids, phytosterols, and tocols, are generally more concentrated in the bran and germ than in the endosperm, and are removed during the refining process. These phytochemicals may contribute importantly to the putative health benefits associated with increased consumption of whole wheat products (Belobrajdic & Bird, 2013; Okarter & Liu, 2010). AR consist of a phenolic ring with two hydroxyl moieties in the meta position and an odd numbered alkyl chain attached to carbon 5 (C5) in the benzene ring. "
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    ABSTRACT: Abstract Whole wheat contains an array of phytochemicals. We quantified alkylresorcinols (AR), phenolic acids, phytosterols, and tocols in six whole wheat products and characterized their antioxidant capacity and ability to induce quinone reductase activity (QR). Total AR content ranged from 136.8 to 233.9 µg/g and was correlated with whole wheat content (r = 0.9248; p = 0.0083). Ferulic acid (FerA) was the dominant phenolic at 99.9-316.0 µg/g and mostly bound tightly to the wheat matrix. AR-C21 and total FerA predicted the whole wheat content in each product (R(2 )= 0.9933). Total phytosterol content ranged from 562.6 to 1035.5 µg/g. Total tocol content ranged from 19.3 to 292.7 µg/g. Phytosterol and tocol contents were independent of whole wheat content. Whole wheat biscuits and pasta were the most potent products to induce QR in Hepa1c1c7 cells. This study provides a platform to characterize the relationship between the phytochemical composition of whole wheat and products formulated with this whole grain.
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