Effect of dietary protein on lipid and glucose metabolism: implications for metabolic health

A. Rietman

Research output: Thesisinternal PhD, WU

Abstract

Abstract

Background: Diet is an important factor in the development of the Metabolic Syndrome (Mets) and type 2 Diabetes Mellitus. Accumulation of intra hepatic lipid (IHL) can result in non-alcoholic fatty liver disease (NAFLD), which is sometimes considered the hepatic manifestation of Mets. Manipulation of the dietary macronutrient composition – altering either fat or simple carbohydrates – has the potential to change lipid storage in the liver. Protein also has this ability, however human data is scarce. Moreover, high dietary protein intake is linked with an increased type 2 Diabetes risk. Therefore, it is essential to study the metabolic consequences of changes in macronutrient composition focussing on altering dietary protein quantity.

Objective: In this thesis the effects of dietary protein on metabolic health focusing on lipid and glucose metabolism were investigated in both observational studies as well as in a human dietary intervention trial.

Methods: In an observational study (n=1283), Fatty Liver Index (FLI) was calculated and related to macronutrient consumption from dietary assessment data. In a controlled dietary intervention, participants (n=27) were assigned to either a control-diet for 4 weeks, or a high-fat, hypercaloric diet, with either a high-protein or a normal-protein content for two weeks, and vice versa. Measurements of IHL (1H-MRS) and blood plasma glucose and lipid concentrations were performed, both in the fasting state and following a meal.

Results: In the observational study, the prevalence of fatty liver as indicated by an FLI>60, was 22.0%. Compared to persons with a normal FLI score of <30, protein intake was positively related with high FLI score >60 (OR: 1.26 per 1 en%, 95%CI 1.16-1.37). This was in particular the case for protein intake from animal sources. In the dietary intervention study, the high-protein diet compared to the normal-protein diet resulted in lower IHL and plasma TG concentrations (IHL: 0.35 ± 0.04 % vs. 0.51 ± 0.08 %; p=0.08; TG: 0.65 ± 0.03 vs. 0.77 ± 0.05 mmol/L; p=0.07). Furthermore, after the meal challenge the free fatty acids (FFA) response was significant different between all three intervention diets (p=0.03). Moreover, the postprandial glucose response was significantly lower after adaptation to NP compared with HP (p=0.03), without differences in the postprandial insulin responses (p=0.37).

Conclusions: From data of the intervention study and observational studies reported in this thesis, it can be concluded that dietary protein intake is associated with alterations in metabolic profile, with both favourable and potential unfavorable health outcomes. On the short term increasing dietary protein in healthy subjects improved lipid metabolism, as seen by lower TG and IHL levels, but not glucose metabolism. On the long term, however, a high-protein intake was related to a fatty liver, and associated to insulin resistance.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Kok, Frans, Promotor
  • Tomé, D., Promotor, External person
  • Mensink, Marco, Co-promotor
Award date11 Sep 2015
Place of PublicationWageningen
Publisher
Print ISBNs9789462573482
Publication statusPublished - 2015

Fingerprint

Dietary Proteins
Lipid Metabolism
Fatty Liver
Lipids
Glucose
Liver
Health
Observational Studies
Diet
Proteins
Type 2 Diabetes Mellitus
Meals
Aptitude
Metabolome
High Fat Diet
Nonesterified Fatty Acids
Insulin Resistance
Blood Glucose
Fasting
Healthy Volunteers

Keywords

  • nutrition and health
  • metabolic disorders
  • protein intake
  • diet
  • metabolism
  • lipids
  • glucose
  • macronutrients

Cite this

Rietman, A.. / Effect of dietary protein on lipid and glucose metabolism: implications for metabolic health. Wageningen : Wageningen University, 2015. 160 p.
@phdthesis{7582a92471c1413584133f028a5fc969,
title = "Effect of dietary protein on lipid and glucose metabolism: implications for metabolic health",
abstract = "Abstract Background: Diet is an important factor in the development of the Metabolic Syndrome (Mets) and type 2 Diabetes Mellitus. Accumulation of intra hepatic lipid (IHL) can result in non-alcoholic fatty liver disease (NAFLD), which is sometimes considered the hepatic manifestation of Mets. Manipulation of the dietary macronutrient composition – altering either fat or simple carbohydrates – has the potential to change lipid storage in the liver. Protein also has this ability, however human data is scarce. Moreover, high dietary protein intake is linked with an increased type 2 Diabetes risk. Therefore, it is essential to study the metabolic consequences of changes in macronutrient composition focussing on altering dietary protein quantity. Objective: In this thesis the effects of dietary protein on metabolic health focusing on lipid and glucose metabolism were investigated in both observational studies as well as in a human dietary intervention trial. Methods: In an observational study (n=1283), Fatty Liver Index (FLI) was calculated and related to macronutrient consumption from dietary assessment data. In a controlled dietary intervention, participants (n=27) were assigned to either a control-diet for 4 weeks, or a high-fat, hypercaloric diet, with either a high-protein or a normal-protein content for two weeks, and vice versa. Measurements of IHL (1H-MRS) and blood plasma glucose and lipid concentrations were performed, both in the fasting state and following a meal. Results: In the observational study, the prevalence of fatty liver as indicated by an FLI>60, was 22.0{\%}. Compared to persons with a normal FLI score of <30, protein intake was positively related with high FLI score >60 (OR: 1.26 per 1 en{\%}, 95{\%}CI 1.16-1.37). This was in particular the case for protein intake from animal sources. In the dietary intervention study, the high-protein diet compared to the normal-protein diet resulted in lower IHL and plasma TG concentrations (IHL: 0.35 ± 0.04 {\%} vs. 0.51 ± 0.08 {\%}; p=0.08; TG: 0.65 ± 0.03 vs. 0.77 ± 0.05 mmol/L; p=0.07). Furthermore, after the meal challenge the free fatty acids (FFA) response was significant different between all three intervention diets (p=0.03). Moreover, the postprandial glucose response was significantly lower after adaptation to NP compared with HP (p=0.03), without differences in the postprandial insulin responses (p=0.37). Conclusions: From data of the intervention study and observational studies reported in this thesis, it can be concluded that dietary protein intake is associated with alterations in metabolic profile, with both favourable and potential unfavorable health outcomes. On the short term increasing dietary protein in healthy subjects improved lipid metabolism, as seen by lower TG and IHL levels, but not glucose metabolism. On the long term, however, a high-protein intake was related to a fatty liver, and associated to insulin resistance.",
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author = "A. Rietman",
note = "WU thesis 6120",
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language = "English",
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Rietman, A 2015, 'Effect of dietary protein on lipid and glucose metabolism: implications for metabolic health', Doctor of Philosophy, Wageningen University, Wageningen.

Effect of dietary protein on lipid and glucose metabolism: implications for metabolic health. / Rietman, A.

Wageningen : Wageningen University, 2015. 160 p.

Research output: Thesisinternal PhD, WU

TY - THES

T1 - Effect of dietary protein on lipid and glucose metabolism: implications for metabolic health

AU - Rietman, A.

N1 - WU thesis 6120

PY - 2015

Y1 - 2015

N2 - Abstract Background: Diet is an important factor in the development of the Metabolic Syndrome (Mets) and type 2 Diabetes Mellitus. Accumulation of intra hepatic lipid (IHL) can result in non-alcoholic fatty liver disease (NAFLD), which is sometimes considered the hepatic manifestation of Mets. Manipulation of the dietary macronutrient composition – altering either fat or simple carbohydrates – has the potential to change lipid storage in the liver. Protein also has this ability, however human data is scarce. Moreover, high dietary protein intake is linked with an increased type 2 Diabetes risk. Therefore, it is essential to study the metabolic consequences of changes in macronutrient composition focussing on altering dietary protein quantity. Objective: In this thesis the effects of dietary protein on metabolic health focusing on lipid and glucose metabolism were investigated in both observational studies as well as in a human dietary intervention trial. Methods: In an observational study (n=1283), Fatty Liver Index (FLI) was calculated and related to macronutrient consumption from dietary assessment data. In a controlled dietary intervention, participants (n=27) were assigned to either a control-diet for 4 weeks, or a high-fat, hypercaloric diet, with either a high-protein or a normal-protein content for two weeks, and vice versa. Measurements of IHL (1H-MRS) and blood plasma glucose and lipid concentrations were performed, both in the fasting state and following a meal. Results: In the observational study, the prevalence of fatty liver as indicated by an FLI>60, was 22.0%. Compared to persons with a normal FLI score of <30, protein intake was positively related with high FLI score >60 (OR: 1.26 per 1 en%, 95%CI 1.16-1.37). This was in particular the case for protein intake from animal sources. In the dietary intervention study, the high-protein diet compared to the normal-protein diet resulted in lower IHL and plasma TG concentrations (IHL: 0.35 ± 0.04 % vs. 0.51 ± 0.08 %; p=0.08; TG: 0.65 ± 0.03 vs. 0.77 ± 0.05 mmol/L; p=0.07). Furthermore, after the meal challenge the free fatty acids (FFA) response was significant different between all three intervention diets (p=0.03). Moreover, the postprandial glucose response was significantly lower after adaptation to NP compared with HP (p=0.03), without differences in the postprandial insulin responses (p=0.37). Conclusions: From data of the intervention study and observational studies reported in this thesis, it can be concluded that dietary protein intake is associated with alterations in metabolic profile, with both favourable and potential unfavorable health outcomes. On the short term increasing dietary protein in healthy subjects improved lipid metabolism, as seen by lower TG and IHL levels, but not glucose metabolism. On the long term, however, a high-protein intake was related to a fatty liver, and associated to insulin resistance.

AB - Abstract Background: Diet is an important factor in the development of the Metabolic Syndrome (Mets) and type 2 Diabetes Mellitus. Accumulation of intra hepatic lipid (IHL) can result in non-alcoholic fatty liver disease (NAFLD), which is sometimes considered the hepatic manifestation of Mets. Manipulation of the dietary macronutrient composition – altering either fat or simple carbohydrates – has the potential to change lipid storage in the liver. Protein also has this ability, however human data is scarce. Moreover, high dietary protein intake is linked with an increased type 2 Diabetes risk. Therefore, it is essential to study the metabolic consequences of changes in macronutrient composition focussing on altering dietary protein quantity. Objective: In this thesis the effects of dietary protein on metabolic health focusing on lipid and glucose metabolism were investigated in both observational studies as well as in a human dietary intervention trial. Methods: In an observational study (n=1283), Fatty Liver Index (FLI) was calculated and related to macronutrient consumption from dietary assessment data. In a controlled dietary intervention, participants (n=27) were assigned to either a control-diet for 4 weeks, or a high-fat, hypercaloric diet, with either a high-protein or a normal-protein content for two weeks, and vice versa. Measurements of IHL (1H-MRS) and blood plasma glucose and lipid concentrations were performed, both in the fasting state and following a meal. Results: In the observational study, the prevalence of fatty liver as indicated by an FLI>60, was 22.0%. Compared to persons with a normal FLI score of <30, protein intake was positively related with high FLI score >60 (OR: 1.26 per 1 en%, 95%CI 1.16-1.37). This was in particular the case for protein intake from animal sources. In the dietary intervention study, the high-protein diet compared to the normal-protein diet resulted in lower IHL and plasma TG concentrations (IHL: 0.35 ± 0.04 % vs. 0.51 ± 0.08 %; p=0.08; TG: 0.65 ± 0.03 vs. 0.77 ± 0.05 mmol/L; p=0.07). Furthermore, after the meal challenge the free fatty acids (FFA) response was significant different between all three intervention diets (p=0.03). Moreover, the postprandial glucose response was significantly lower after adaptation to NP compared with HP (p=0.03), without differences in the postprandial insulin responses (p=0.37). Conclusions: From data of the intervention study and observational studies reported in this thesis, it can be concluded that dietary protein intake is associated with alterations in metabolic profile, with both favourable and potential unfavorable health outcomes. On the short term increasing dietary protein in healthy subjects improved lipid metabolism, as seen by lower TG and IHL levels, but not glucose metabolism. On the long term, however, a high-protein intake was related to a fatty liver, and associated to insulin resistance.

KW - voeding en gezondheid

KW - stofwisselingsstoornissen

KW - eiwitinname

KW - dieet

KW - metabolisme

KW - lipiden

KW - glucose

KW - macronutriënten

KW - nutrition and health

KW - metabolic disorders

KW - protein intake

KW - diet

KW - metabolism

KW - lipids

KW - glucose

KW - macronutrients

M3 - internal PhD, WU

SN - 9789462573482

PB - Wageningen University

CY - Wageningen

ER -