Cholesterol levels drop in Western nations including New Zealand, but rise in Asia and some Pacific Island nations
posted by Research Admin 1 on 11 June 2020
National Science Challenge, June, 2020
Cholesterol levels are declining sharply in high income, western nations including New Zealand, but rising in low- and middle-income nations – particularly in Asia, suggests the largest ever study of global cholesterol levels. Levels are also very high in several Pacific Island nations, with Tokelau reported as having among the highest levels worldwide.
The new study, by hundreds of researchers from across the world was led by Professor Majid Ezzati of Imperial College London and has just been published in the journal Nature. The New Zealand contribution came from Healthier Lives researchers Professor Rod Jackson (University of Auckland) Professor Jim Mann (University of Otago, and Director of Healthier Lives). Professor Jackson was a member of the study design team and was also involved in the interpretation of the data and writing of the paper, Professor Mann provided cholesterol data from New Zealand and contributed to data interpretation.
The research used data from 102.6 million individuals and examined cholesterol levels in 200 countries, across a 39-year time period, from 1980 to 2018.
The work, which was funded by the Wellcome Trust and the British Heart Foundation, revealed that high cholesterol is responsible for about 3.9 million worldwide deaths. Half of these deaths happen in East, South and Southeast Asia.
Cholesterol is a waxy substance found in the blood. The body needs cholesterol to build healthy cells, but too much can lead to a build-up in the blood vessels. Cholesterol comes in different types. High-density lipoprotein (HDL) ‘good’ cholesterol, which should be 1mmol/L or above, is thought to have a protective effect against heart attack and stroke, by mopping up excess ‘bad’ cholesterol.
Non-HDL ‘bad’ cholesterol, which should be as low as possible, ideally around 2mmol/L, can block blood supply and lead to heart attacks and strokes. Levels tend to increase when individuals and populations increase their intake of saturated and trans fats, which are found in many processed foods, and decrease when saturated and trans fats are replaced by unsaturated plant-based oils, Statin drugs can appreciably lower non-HDL cholesterol.
The results of the new study revealed total and non-HDL cholesterol levels have fallen sharply in high income nations, particularly those in North-western Europe, North America and Australasia, while rising in low- and middle-income nations, particularly in East and Southeast Asia. China, which had some of the lowest levels of non-HDL cholesterol in 1980, had one of the largest rates of increase in non-HDL over the 39 year study period.
In New Zealand, population mean cholesterol decreased from 6.2 mmol/L in 1989 to 5.4 mmol/L in 2008/09. The change in several Pacific Island states was in the opposite direction.
“The fall in cholesterol in New Zealand is substantially larger than reported from many other high income countries. It has occurred in parallel with a reduction in dietary saturated fat, an increase in unsaturated fat, and a reduction in coronary disease mortality.
“Statin drugs will also have contributed to the fall in cholesterol and heart disease but the encouraging trend emerged before these drugs were widely available in New Zealand,” said Professor Mann.
“The challenge for us in this neck of the woods is to ensure recommendations and policies that will enable all New Zealanders to have and make food choices which will result in a further reduction in the bad non-HDL cholesterol levels. Although mortality rates have fallen, coronary heart disease remains the most common cause of death in middle-aged and older people and rates remain higher than those in Australia,” said Professor Jackson.
“Similar action is urgently required in those Pacific Island nations where cholesterol levels have increased and statin drugs need to be readily available wherever this is not the case.”
Professor Majid Ezzati, lead author of the research from Imperial’s School of Public Health, said: “For the first time, the highest levels of non-HDL cholesterol are outside of the Western World.” This suggests we now need to set into place, throughout the world, pricing and regulatory policies that shift diets from saturated to non-saturated fats, and to prepare health systems to treat those in needs with effective medicines. This will help save millions of deaths from high non-HDL cholesterol in these regions.”
Taddei, C., Zhou, B., Bixby, H. et al. Repositioning of the global epicentre of non-optimal cholesterol, Nature, 582, pages 73–77 (2020)
To read the full article, go to: https://doi.org/10.1038/s41586-020-2338-1