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Contributor: PR Newswire Europe
Friday, August 07 2020 - 03:55
Dietary cholesterol and phytosterols contribute directly to heart disease
REYKJAVIK, Iceland, August 6, 2020, /PRNewswire-AsiaNet/--

Genetic variability in cholesterol and phytosterol absorption affects 
cardiovascular disease risk

Scientists at deCODE genetics, a subsidiary of Amgen, and their collaborators 
from the Icelandic healthcare system, University of Iceland, the Copenhagen 
University Biobank and the Danish Blood Donor Study, recently published a study 
in European Heart Journal, with new findings that point to harmful effects of 
dietary cholesterol and phytosterols. 

It is well established that the "bad" cholesterol (also called non-HDL 
cholesterol and LDL cholesterol) directly affects the development of 
cardiovascular disease. Individuals who have high blood levels of bad 
cholesterol, or are at high risk of heart disease for other reasons, are 
generally advised to lower their cholesterol levels through lifestyle changes, 
and sometimes receive treatment with cholesterol-lowering drugs such as statins.

Blood levels of cholesterol are affected by both genetics and the environment, 
diet in particular, with the consumption of saturated fats, found primarily in 
red meat and high-fat dairy foods, increasing blood cholesterol. However, the 
importance of dietary cholesterol in the regulation of cholesterol levels in 
the blood and the risk of heart disease has been the subject of controversy for 
decades. Most foods that are rich in cholesterol are also high in saturated 
fats with some exceptions, including eggs and shellfish.

Phytosterols are cholesterol-like molecules found in small amount in all plant 
foods, including fruits, vegetables, nuts and legumes. Food enriched with high 
amounts of phytosterols, mainly margarine and dairy products, is commonly 
recommended as part of heart-healthy diet as it may decrease the absorption of 
dietary cholesterol.

The transporter proteins NPC1L1 and ABCG5/8 control the absorption of dietary 
cholesterol and phytosterols. NPC1L1 transports sterols from the intestinal 
lumen into enterocytes where ABCG5/8 excretes less than half of the cholesterol 
but most of the phytosterols back into the intestinal lumen. Thus, we generally 
absorb about 50-60% of the intestinal dietary cholesterol but only 5% of 
dietary phytosterols. 

The authors studied the effects of sequence variants that modulate the function 
of the ABCG5/8 transporter on blood levels of cholesterol and phytosterols and 
the risk of coronary artery disease in large sample sets from Iceland, Denmark 
and the UK Biobank. The effects of the sequence variants were measured in up to 
147 thousand patients with coronary artery disease and 922 thousand individuals 
without disease.

The study showed that individuals who harbor sequence variants that decrease 
the function of ABCG5/8 transporter have increased blood levels of both 
cholesterol and phytosterols and increased risk of heart disease. These results 
confirm that dietary cholesterol affects blood levels of cholesterol and risk 
of heart attacks. The results also demonstrate that people absorb variable 
amounts of the cholesterol they consume.

The study also showed that the effect of the ABCG5/8 variants, influencing both 
levels of cholesterol and phytosterol, on risk of heart disease, was greater 
than of other cholesterol variants that do not affect phytosterol levels. These 
results support the notion that phytosterols may contribute directly to 
atherogenesis, raising questions about the safety of supplementing food with 

In the accompanying Editorial, Oliver Weingärtner states that "The study by 
Helgadottir et al. is not only the best study so far to support the hypothesis 
that variations at the ABCG5/ABCG8 locus is mechanistically involved in 
atherosclerotic heart disease, but it also lends a strong impetus to study the 
role of xenosterols in this process too."

Based in Reykjavik, Iceland, deCODE is a global leader in analyzing and 
understanding the human genome. Using its unique expertise in human genetics 
combined with growing expertise in transcriptomics and population proteomics 
and vast amount of phenotypic data, deCODE has discovered risk factors for 
dozens of common diseases and provided key insights into their pathogenesis. 
The purpose of understanding the genetics of disease is to use that information 
to create new means of diagnosing, treating and preventing disease. deCODE is a 
wholly-owned subsidiary of Amgen (NASDAQ: AMGN).

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Thora Kristin Asgeirsdottir 
PR and Communications 
deCODE genetics 
+354 570 1909 
+354 894 1909

SOURCE: DeCODE Genetics Inc