Featured Research

from universities, journals, and other organizations

Carbohydrate digestion and obesity strongly linked

Date:
March 30, 2014
Source:
Imperial College London
Summary:
New research indicates that obesity in the general population may be genetically linked to how our bodies digest carbohydrates. People usually have two copies of the gene AMY1, but in some regions of our DNA there can be variability in the number of copies a person carries, which is known as copy number variation. The number of copies of AMY1 can be highly variable between people, and it is believed that higher numbers of copies of the salivary amylase gene have evolved in response to a shift towards diets containing more starch since prehistoric times.

New research indicates that obesity in the general population may be genetically linked to how our bodies digest carbohydrates.
Credit: Rozmaryna / Fotolia

New research indicates that obesity in the general population may be genetically linked to how our bodies digest carbohydrates.

Published today in the journal Nature Genetics, the study investigated the relationship between body weight and a gene called AMY1, which is responsible for an enzyme present in our saliva known as salivary amylase. This enzyme is the first to be encountered by food when it enters the mouth, and it begins the process of starch digestion that then continues in the gut.

People usually have two copies of each gene, but in some regions of our DNA there can be variability in the number of copies a person carries, which is known as copy number variation. The number of copies of AMY1 can be highly variable between people, and it is believed that higher numbers of copies of the salivary amylase gene have evolved in response to a shift towards diets containing more starch since prehistoric times.

Researchers from Imperial College London, in collaboration with other international institutions, looked at the number of copies of the gene AMY1 present in the DNA of thousands of people from the UK, France, Sweden and Singapore. They found that people who carried a low number of copies of the salivary amylase gene were at greater risk of obesity.

The chance of being obese for people with less than four copies of the AMY1 gene was approximately eight times higher than in those with more than nine copies of this gene. The researchers estimated that with every additional copy of the salivary amylase gene there was approximately a 20 per cent decrease in the odds of becoming obese.

Professor Philippe Froguel, Chair in Genomic Medicine in the School of Public Health at Imperial College London, and one of the lead authors on the study, said: "I think this is an important discovery because it suggests that how we digest starch and how the end products from the digestion of complex carbohydrates behave in the gut could be important factors in the risk of obesity. Future research is needed to understand whether or not altering the digestion of starchy food might improve someone's ability to lose weight, or prevent a person from becoming obese. We are also interested in whether there is a link between this genetic variation and people's risk of other metabolic disorders such as diabetes, as people with a low number of copies of the salivary amylase gene may also be glucose intolerant."

Dr Mario Falchi, also from Imperial's School of Public Health and first author of the study, said: "Previous genetic studies investigating obesity have tended to identify variations in genes that act in the brain and often result in differences in appetite, whereas our finding is related to how the body physically handles digestion of carbohydrates. We are now starting to develop a clearer picture of a combination of genetic factors affecting psychological and metabolic processes that contribute to people's chances of becoming obese. This should ultimately help us to find better ways of tackling obesity."

Dr Julia El-Sayed Moustafa, another lead author from Imperial's School of Public Health, said: "Previous studies have found rare genetic variations causing extreme forms of obesity, but because they occur in only a small number of people, they explained very little of the differences in body weight we see in the population. On the other hand, research on more common genetic variations that increase risk of obesity in the general population have so far generally found only a modest effect on obesity risk. This study is novel in that it identifies a genetic variation that is both common and has a relatively large effect on the risk of obesity in the general population. The number of copies of the salivary amylase gene is highly variable between people, and so, given this finding, can potentially have a large impact on our individual risk of obesity."

The first step of the study involved the analysis of genetic data from a Swedish family sample of 481 participants, recruited on the basis of sibling-pairs where one was obese and the other non-obese. The researchers used these data to short-list genes whose copy number differences influence body mass index (BMI), and identified the gene coding for the enzyme salivary amylase (AMY1) as the one with the greatest influence on body weight in their analysis. They then investigated the relationship between the number of times the AMY1 gene was repeated on chromosome 1 in each individual and their risk of obesity, by studying approximately 5,000 subjects from France and the UK.

The researchers also expanded their study to include approximately 700 obese and normal-weight people from Singapore, and demonstrated that the same relationship between the number of copies of the AMY1 gene and the risk of obesity also existed in non-Europeans.

The study was funded by the Wellcome Trust and the Medical Research Council.


Story Source:

The above story is based on materials provided by Imperial College London. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. Falchi et al. Low copy number of the salivary amylase gene predisposes to obesity. Nature Genetics, 2014 DOI: 10.1038/ng.2939

Cite This Page:

Imperial College London. "Carbohydrate digestion and obesity strongly linked." ScienceDaily. ScienceDaily, 30 March 2014. <www.sciencedaily.com/releases/2014/03/140330151318.htm>.
Imperial College London. (2014, March 30). Carbohydrate digestion and obesity strongly linked. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2014/03/140330151318.htm
Imperial College London. "Carbohydrate digestion and obesity strongly linked." ScienceDaily. www.sciencedaily.com/releases/2014/03/140330151318.htm (accessed July 30, 2014).

Share This




More Health & Medicine News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Generics Eat Into Pfizer's Sales

Generics Eat Into Pfizer's Sales

Reuters - Business Video Online (July 29, 2014) Pfizer, the world's largest drug maker, cut full-year revenue forecasts because generics could cut into sales of its anti-arthritis drug, Celebrex. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Nigeria Ups Ebola Stakes on 1st Death

Nigeria Ups Ebola Stakes on 1st Death

Reuters - Business Video Online (July 29, 2014) Nigerian authorities have shut and quarantined a Lagos hospital where a Liberian man died of the Ebola virus, the first recorded case of the highly-infectious disease in Africa's most populous economy. David Pollard reports Video provided by Reuters
Powered by NewsLook.com
Running 5 Minutes A Day Might Add Years To Your Life

Running 5 Minutes A Day Might Add Years To Your Life

Newsy (July 29, 2014) According to a new study, just five minutes of running or jogging a day could add years to your life. Video provided by Newsy
Powered by NewsLook.com
Ebola Outbreak Poses Little Threat To U.S.: CDC

Ebola Outbreak Poses Little Threat To U.S.: CDC

Newsy (July 29, 2014) The Ebola outbreak in West Africa poses little threat to Americans, according to officials with the Centers for Disease Control and Prevention. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins