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Dietary starch intake modifies the relation between copy number variation in the salivary amylase gene and BMI

Rukh, Gull LU ; Ericson, Ulrika LU ; Andersson-Assarsson, Johanna; Orho-Melander, Marju LU and Sonestedt, Emily LU (2017) In American Journal of Clinical Nutrition 106(1). p.256-262
Abstract

Background: Studies have shown conflicting associations between the salivary amylase gene (AMY1) copy number and obesity. Salivary amylase initiates starch digestion in the oral cavity; starch is a major source of energy in the diet. Objective: We investigated the association between AMY1 copy number and obesity traits, and the effect of the interaction between AMY1 copy number and starch intake on these obesity traits. Design: We first assessed the association between AMY1 copy number (genotyped by digital droplet polymerase chain reaction) and obesity traits in 4800 individuals without diabetes (mean age: 57 y; 60% female) from the Malmö Diet and Cancer Cohort. Then we analyzed interactions between AMY1 copy number and energyadjusted... (More)

Background: Studies have shown conflicting associations between the salivary amylase gene (AMY1) copy number and obesity. Salivary amylase initiates starch digestion in the oral cavity; starch is a major source of energy in the diet. Objective: We investigated the association between AMY1 copy number and obesity traits, and the effect of the interaction between AMY1 copy number and starch intake on these obesity traits. Design: We first assessed the association between AMY1 copy number (genotyped by digital droplet polymerase chain reaction) and obesity traits in 4800 individuals without diabetes (mean age: 57 y; 60% female) from the Malmö Diet and Cancer Cohort. Then we analyzed interactions between AMY1 copy number and energyadjusted starch intake (obtained by a modified diet history method) on body mass index (BMI) and body fat percentage. Results: AMY1 copy number was not associated with BMI (P = 0.80) or body fat percentage (P = 0.38). We observed a significant effect of the interaction between AMY1 copy number and starch intake on BMI (P-interaction = 0.007) and body fat percentage (P-interaction = 0.03). Upon stratification by dietary starch intake, BMI tended to decrease with increasing AMY1 copy numbers in the low-starch intake group (P = 0.07) and tended to increase with increasing AMY1 copy numbers in the high-starch intake group (P = 0.08). The lowest mean BMI was observed in the group of participants with a low AMY1 copy number and a high dietary intake of starch. Conclusions: Our findings suggest an effect of the interaction between starch intake and AMY1 copy number on obesity. Individuals with high starch intake but low genetic capacity to digest starch had the lowest BMI, potentially because larger amounts of undigested starch are transported through the gastrointestinal tract, contributing to fewer calories extracted from ingested starch. Am J Clin Nutr 2017;106:256-62.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cohort, Copy number variation, Gene-diet interaction, Obesity, Salivary amylase, Starch
in
American Journal of Clinical Nutrition
volume
106
issue
1
pages
7 pages
publisher
American Society for Clinical Nutrition
external identifiers
  • scopus:85021809368
  • wos:000404593900032
ISSN
0002-9165
DOI
10.3945/ajcn.116.149831
language
English
LU publication?
yes
id
1d542739-c5a4-495a-b09f-48dd24a64a01
date added to LUP
2017-07-25 15:01:32
date last changed
2017-09-18 11:39:27
@article{1d542739-c5a4-495a-b09f-48dd24a64a01,
  abstract     = {<p>Background: Studies have shown conflicting associations between the salivary amylase gene (AMY1) copy number and obesity. Salivary amylase initiates starch digestion in the oral cavity; starch is a major source of energy in the diet. Objective: We investigated the association between AMY1 copy number and obesity traits, and the effect of the interaction between AMY1 copy number and starch intake on these obesity traits. Design: We first assessed the association between AMY1 copy number (genotyped by digital droplet polymerase chain reaction) and obesity traits in 4800 individuals without diabetes (mean age: 57 y; 60% female) from the Malmö Diet and Cancer Cohort. Then we analyzed interactions between AMY1 copy number and energyadjusted starch intake (obtained by a modified diet history method) on body mass index (BMI) and body fat percentage. Results: AMY1 copy number was not associated with BMI (P = 0.80) or body fat percentage (P = 0.38). We observed a significant effect of the interaction between AMY1 copy number and starch intake on BMI (P-interaction = 0.007) and body fat percentage (P-interaction = 0.03). Upon stratification by dietary starch intake, BMI tended to decrease with increasing AMY1 copy numbers in the low-starch intake group (P = 0.07) and tended to increase with increasing AMY1 copy numbers in the high-starch intake group (P = 0.08). The lowest mean BMI was observed in the group of participants with a low AMY1 copy number and a high dietary intake of starch. Conclusions: Our findings suggest an effect of the interaction between starch intake and AMY1 copy number on obesity. Individuals with high starch intake but low genetic capacity to digest starch had the lowest BMI, potentially because larger amounts of undigested starch are transported through the gastrointestinal tract, contributing to fewer calories extracted from ingested starch. Am J Clin Nutr 2017;106:256-62.</p>},
  author       = {Rukh, Gull and Ericson, Ulrika and Andersson-Assarsson, Johanna and Orho-Melander, Marju and Sonestedt, Emily},
  issn         = {0002-9165},
  keyword      = {Cohort,Copy number variation,Gene-diet interaction,Obesity,Salivary amylase,Starch},
  language     = {eng},
  month        = {07},
  number       = {1},
  pages        = {256--262},
  publisher    = {American Society for Clinical Nutrition},
  series       = {American Journal of Clinical Nutrition},
  title        = {Dietary starch intake modifies the relation between copy number variation in the salivary amylase gene and BMI},
  url          = {http://dx.doi.org/10.3945/ajcn.116.149831},
  volume       = {106},
  year         = {2017},
}