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METABOLIC PROPERTIES OF RYE PRODUCTS Focusing on insulinaemia, glycaemic profile and appetite regulation in healthy subjects

Rosén, Liza LU (2011)
Abstract (Swedish)
Popular Abstract in Swedish

Förekomsten av välfärdssjukdomar såsom diabetes och hjärt-kärlsjukdomar ökar kraftigt och det finns därför ett stort behov av preventiva åtgärder. Ett förstadium till dessa allvarliga sjukdomar är insulinresistens syndromet (IRS), även känt som det metabola syndromet. IRS utgör ett kluster av flera metabola störningar såsom bukfetma, högt blodtryck, förhöjda blodfetter och förhöjt blodsocker. IRS kan förebyggas genom lämplig kost och livsmedel innehållande fullkorn respektive livsmedel som gynnar ett lågt blodsocker och insulinsvar efter måltid (lågt GI och II) har visats vara skyddande. Egenskaper hos råg är av intresse i detta sammanhang, då råg ofta äts som fullkorn och ger ett lågt... (More)
Popular Abstract in Swedish

Förekomsten av välfärdssjukdomar såsom diabetes och hjärt-kärlsjukdomar ökar kraftigt och det finns därför ett stort behov av preventiva åtgärder. Ett förstadium till dessa allvarliga sjukdomar är insulinresistens syndromet (IRS), även känt som det metabola syndromet. IRS utgör ett kluster av flera metabola störningar såsom bukfetma, högt blodtryck, förhöjda blodfetter och förhöjt blodsocker. IRS kan förebyggas genom lämplig kost och livsmedel innehållande fullkorn respektive livsmedel som gynnar ett lågt blodsocker och insulinsvar efter måltid (lågt GI och II) har visats vara skyddande. Egenskaper hos råg är av intresse i detta sammanhang, då råg ofta äts som fullkorn och ger ett lågt insulinsvar. I avhandlingen har rågprodukter studerats med avseende på insulin och blodsockersvar samt påverkan på mättnad.

Fullkornsrågprodukter, både hela kokta kärnor och bröd samt rågbröd och gröt gjort av vitt rågmjöl har i denna avhandling visats ge ett lågt insulinsvar samt ett välreglerat blodsockersvar, med lägre maximal stigning och med mindre blodsockerfall i den sena fasen efter måltid än motsvarande produkter gjorda på vitt vetemjöl. Det låga insulin- och blodsockersvaren beror troligen på en kombination av en hög andel lösliga fibrer, närvaro av bioaktiva komponenter såsom fenolsyror samt en tät livsmedelsstruktur. Dessa faktorer har förmågan att sänka spjälknings- och/eller upptagningshastigheten för kolhydrater från tarmen och därmed ge ett mer välkontrollerat blodsockersvar efter måltid.

Rågprodukter och då främst kokta rågkärnor, visade sig ge en bra mättnadskänsla, både direkt efter måltid och vid en efterföljande måltid. En frukost bestående kokta rågkärnor sänkte således energiintaget vid en efterkommande lunchmåltid med i genomsnitt 16 energiprocent. Mekanismen bakom denna effekt tros vara en hög andel mättande fibrer samt de välkontrollerade insulin och glukossvaren som dämpade halten av hungerhormonet ghrelin i den sena fasen efter frukostmåltiden. Kostfiber i rågprodukter var snabbt åtkomliga för tarmflorans bakterier, och ett samband erhölls mellan bildning av en metabolit från denna fermentering (vätgas i utandningsluft) och gynnsamma effekter på blodsockerreglering respektive mättnadskänsla.

Val av rågsort och produkt-processning visade sig påverka blodsockersvar, insulinbehov samt mättnad efter måltid. Produkter baserade på hela kokta kärnor och bröd av fullkorn och vitt rågmjöl gav lägre insulin- och blodglukossvar än rågmjölsgrötar, medan rågmjölsgrötarna och de hela kokta kärnorna var mest mättande.

Resultaten antyder att flera komponenter i råg sannolikt bidrar till rågprodukters gynnsamma effekter på blodsockerreglering och mättnad. En mekanism tycks vara kopplad till rågprodukternas innehåll av lättfermenterbara kostfiber.



(Less)
Abstract
The prevalence of metabolic disorders, such as type 2 diabetes, cardiovascular diseases and the insulin resistance syndrome (IRS) are increasing worldwide. However, disturbances in the metabolic status can be prevented by changing the daily diet towards more whole grains, vegetables, legumes and dairy products. Also the dietary glycaemic- and insulinaemic indices of foods may play a role. Rye products are interesting in this context as they are usually consumed in wholegrain form and have been demonstrated to induce low insulin responses, with or without a simultaneous lowering of the glycaemic index (GI). The objective of this thesis was to evaluate the possible cause of low postprandial insulin response to rye, and to elucidate potential... (More)
The prevalence of metabolic disorders, such as type 2 diabetes, cardiovascular diseases and the insulin resistance syndrome (IRS) are increasing worldwide. However, disturbances in the metabolic status can be prevented by changing the daily diet towards more whole grains, vegetables, legumes and dairy products. Also the dietary glycaemic- and insulinaemic indices of foods may play a role. Rye products are interesting in this context as they are usually consumed in wholegrain form and have been demonstrated to induce low insulin responses, with or without a simultaneous lowering of the glycaemic index (GI). The objective of this thesis was to evaluate the possible cause of low postprandial insulin response to rye, and to elucidate potential effects of processing condition, extraction rate and rye variety. Insulin response as well as glycaemic response and course of glycaemia were evaluated in the postprandial phase. Additionally a marker of colonic fermentation was analysed in the postprandial phase (breath hydrogen) and appetite regulating properties were investigated using subjective ratings, analysis of plasma ghrelin, and quantification of voluntary food intake at a subsequent meal.

Wholegrain rye products, ingested as boiled kernels and breads as well as endosperm rye (sifted rye) bread and porridge, induced low insulin responses and also a well regulated course of glycaemia, noted as blood glucose curves with lower incremental peaks, remaining above fasting for a longer time. However, some rye varieties were devoid of benefits on course of glycaemia and insulin economy. Two measurements of the course of glycaemia were introduced, the GP and GP2, defined as the duration for incremental postprandial glycaemic response divided by the glucose incremental peak or squared glucose incremental peak, respectively. The GP and GP2 of the products were correlated to the insulin response, as well as to late subjective satiety, suggesting that they are good predictors of postprandial events. Suggested mechanism for the lowered glycaemic and insulinaemic responses were a high content of viscous fibres, bioactive components, e.g. phenolic acids and a dense food structure, contributing to a lowered digestion and uptake of carbohydrates in the small intestines. Furthermore, rye products induced early colonic fermentation, already in the postprandial phase, possibly explained by the presence of arabinoxylans, fructans, and other dietary fibre compounds of low molecular weight. The increase in colonic fermentation, measured as increase in breath H2, correlated with lower late postprandial concentration of FFA and the GP and GP2 of the products, suggesting increased glucose tolerance already in the postprandial phase after rye products.

Rye products, in particular boiled rye kernels induced high postprandial subjective satiety and promoted satiety also at a subsequent voluntary meal. The rye kernel breakfast lowered the voluntary energy intake at a second meal with 16%. The mechanism behind this satiating effect of rye was suggested to be the high content of dietary fibres (DF) and high water content introducing a bulking effect. Also, high content of viscous and fermentable DF can lower gastric emptying rate. The low postprandial glycaemia and insulinaemia seen with several rye products appears to contribute to a lowered rebound of the hunger peptide ghrelin prior to the second meal.

Rye products made from whole kernels and wholegrain- and endosperm rye bread induced lower postprandial insulinaemia and glycaemia than wholegrain- and endosperm rye porridges, while porridges and whole kernels induced higher subjective satiety. Boiled rye kernels also supressed the desire to eat to a greater extent than boiled wheat kernels in the later postprandial phase (tAUC 210–270 min). Several components are suggested to contribute to the observed lowered insulinaemia, well regulated glycaemia and improved satiating effects of certain rye products. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Profesor Riccardi, Gabriele, Department of Clinical and Experimental Medicine, Frederico II University, Naples, Italy.
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Rye, glycaemia, insulin resistance, type 2 diabetes, wholegrain, obesity
pages
167 pages
defense location
Lecture hall B, Center of Chemistry and Chemical Engineering, Getingevägen 60, Lund University Faculty of Engineering
defense date
2011-06-01 09:15
ISBN
978-91-7422-272-2
language
English
LU publication?
yes
id
9f9a919f-ed3b-40c8-b02e-369be9e057f6 (old id 1940076)
date added to LUP
2011-05-05 14:27:15
date last changed
2016-09-19 08:45:15
@misc{9f9a919f-ed3b-40c8-b02e-369be9e057f6,
  abstract     = {The prevalence of metabolic disorders, such as type 2 diabetes, cardiovascular diseases and the insulin resistance syndrome (IRS) are increasing worldwide. However, disturbances in the metabolic status can be prevented by changing the daily diet towards more whole grains, vegetables, legumes and dairy products. Also the dietary glycaemic- and insulinaemic indices of foods may play a role. Rye products are interesting in this context as they are usually consumed in wholegrain form and have been demonstrated to induce low insulin responses, with or without a simultaneous lowering of the glycaemic index (GI). The objective of this thesis was to evaluate the possible cause of low postprandial insulin response to rye, and to elucidate potential effects of processing condition, extraction rate and rye variety. Insulin response as well as glycaemic response and course of glycaemia were evaluated in the postprandial phase. Additionally a marker of colonic fermentation was analysed in the postprandial phase (breath hydrogen) and appetite regulating properties were investigated using subjective ratings, analysis of plasma ghrelin, and quantification of voluntary food intake at a subsequent meal. <br/><br>
Wholegrain rye products, ingested as boiled kernels and breads as well as endosperm rye (sifted rye) bread and porridge, induced low insulin responses and also a well regulated course of glycaemia, noted as blood glucose curves with lower incremental peaks, remaining above fasting for a longer time. However, some rye varieties were devoid of benefits on course of glycaemia and insulin economy. Two measurements of the course of glycaemia were introduced, the GP and GP2, defined as the duration for incremental postprandial glycaemic response divided by the glucose incremental peak or squared glucose incremental peak, respectively. The GP and GP2 of the products were correlated to the insulin response, as well as to late subjective satiety, suggesting that they are good predictors of postprandial events. Suggested mechanism for the lowered glycaemic and insulinaemic responses were a high content of viscous fibres, bioactive components, e.g. phenolic acids and a dense food structure, contributing to a lowered digestion and uptake of carbohydrates in the small intestines. Furthermore, rye products induced early colonic fermentation, already in the postprandial phase, possibly explained by the presence of arabinoxylans, fructans, and other dietary fibre compounds of low molecular weight. The increase in colonic fermentation, measured as increase in breath H2, correlated with lower late postprandial concentration of FFA and the GP and GP2 of the products, suggesting increased glucose tolerance already in the postprandial phase after rye products.<br/><br>
Rye products, in particular boiled rye kernels induced high postprandial subjective satiety and promoted satiety also at a subsequent voluntary meal. The rye kernel breakfast lowered the voluntary energy intake at a second meal with 16%. The mechanism behind this satiating effect of rye was suggested to be the high content of dietary fibres (DF) and high water content introducing a bulking effect. Also, high content of viscous and fermentable DF can lower gastric emptying rate. The low postprandial glycaemia and insulinaemia seen with several rye products appears to contribute to a lowered rebound of the hunger peptide ghrelin prior to the second meal.<br/><br>
Rye products made from whole kernels and wholegrain- and endosperm rye bread induced lower postprandial insulinaemia and glycaemia than wholegrain- and endosperm rye porridges, while porridges and whole kernels induced higher subjective satiety. Boiled rye kernels also supressed the desire to eat to a greater extent than boiled wheat kernels in the later postprandial phase (tAUC 210–270 min). Several components are suggested to contribute to the observed lowered insulinaemia, well regulated glycaemia and improved satiating effects of certain rye products.},
  author       = {Rosén, Liza},
  isbn         = {978-91-7422-272-2},
  keyword      = {Rye,glycaemia,insulin resistance,type 2 diabetes,wholegrain,obesity},
  language     = {eng},
  pages        = {167},
  title        = {METABOLIC PROPERTIES OF RYE PRODUCTS Focusing on insulinaemia, glycaemic profile and appetite regulation in healthy subjects},
  year         = {2011},
}