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‘Bad’ cholesterol linked with poorer cognitive performance

By Chukwuma Muanya, Assistant Editor (Head Insight Team, Science & Technology)
22 July 2016   |   3:32 am
A study, published this week in the journal Circulation, used a slightly different approach to investigate the interaction. Rather than the overall levels of ‘bad’ cholesterol that is Low Density Lipo-protein (LDL)...
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‘Bad cholesterol-lowering foods… Cholesterol levels are not static in an individual; they can rise and fall, dependent on factors such as exercise, diet, drugs, and impaired homeostasis due to age or disease. Each individual’s cholesterol levels ebb and flow to different degrees; some people’s levels are relatively static, others are more erratic. PHOTO CREDIT: google.com/search

* Eat more healthy fat to reduce type 2 diabetes risk
Previous research into the relationship between cholesterol levels and cognitive (thinking) function in older adults has been inconclusive. The relationship appears to be a complex one.

A study, published this week in the journal Circulation, used a slightly different approach to investigate the interaction. Rather than the overall levels of ‘bad’ cholesterol that is Low Density Lipo-protein (LDL), the team looked at the effects of cholesterol fluctuation on cognitive performance.

Cholesterol levels are not static in an individual; they can rise and fall, dependent on factors such as exercise, diet, drugs, and impaired homeostasis due to age or disease. Each individual’s cholesterol levels ebb and flow to different degrees; some people’s levels are relatively static, others are more erratic.Despite its bad name, cholesterol is essential to the normal functioning of the human body.

Human cell membranes are composed of around 30 percent cholesterol. It plays a vital role in building, maintaining, and keeping membranes functional.
Cholesterol cannot be dissolved in the blood; it is lipoproteins that carry it to the areas of the body where it is needed.Meanwhile, eating more unsaturated fats instead of carbohydrates decreases the risk of developing type 2 diabetes, says research published in PLOS Medicine.

Replacing carbohydrate and saturated fats with healthy fats, such as polyunsaturated fats, lowers blood sugar levels and improves insulin control, according to findings from a new meta-analysis.

Around the world, there has been a sharp increase in the rates of insulin resistance and type 2 diabetes. There are two types of lipoproteins: low-density (LDL) and high-density (HDL).LDL cholesterol is considered “bad” because it helps build a thick, hard plaque that can clog up arteries and stiffen them. This leads to an increased risk of heart attack and stroke.

HDL cholesterol is considered “good” because it helps ferry LDL cholesterol toward the liver where it is broken down.A team of investigators from Leiden University Medical Center in Leiden, Netherlands, set out to see if LDL cholesterol fluctuations had a measurable impact on the brain.

The study used 4,428 participants, aged 70-82, taken from the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). The individuals were from Scotland, the Netherlands, and Ireland.

PROSPER participants are all either at high risk of developing vascular disease or already had a vascular disease diagnosis.Researchers, led by Dr. Roelof Smit, assessed the individual’s LDL cholesterol variability before putting them through a raft of cognitive tests.

These cognitive tests involved a measure of attention that used colored words – an individual is asked to read the word of a color, written in a different color, for instance, the word “red” written in the color blue. They also used an assessment of information processing speed and two verbal memory tests measuring recall and delayed recall after 20 minutes.

Once the results had been analyzed, the team observed that participants with the highest cholesterol variability needed 2.7 seconds longer to finish the colored word test when compared with individuals with the lowest fluctuations.

This link was still significant when factors were taken into account, such as overall high LDL levels and the use of statin drugs, which lower cholesterol.
Although the effect size might seem small, as Smit said, it is “significant at a population level.”To treat existing diabetes, the experts urge people to eat healthily, exercise regularly, and use medications that reduce blood glucose levels. They also emphasize the need to reduce cardiovascular disease risk factors, such as high blood pressure and high lipid levels, and to avoid tobacco use.

Amid urgent calls for new ways to prevent type 2 diabetes, some research has focused on how different carbohydrates and dietary fats impact metabolic health.This has been controversial, and it has led to confusion regarding dietary guidelines and health priorities.

Senior author Dr. Dariush Mozaffarian, dean of the Friedman School of Nutrition Science and Policy at Tufts University in Medford, MA, and first author Fumiaki Imamura, of the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge, United Kingdom, led the meta-analysis.

They looked at data for 4,660 adults that had been collected in 102 studies. In the randomized, controlled trials, the adults were given meals containing various types and quantities of carbohydrate and fat.The researchers examined how these variations in diet impacted measures of metabolic health, and specifically, how saturated, monounsaturated and polyunsaturated fats and carbohydrates impact the development of type 2 diabetes.

The study focused on key biological markers of glucose and insulin control. These were blood sugar, blood insulin, insulin resistance and sensitivity, and how well the body was able to produce insulin in response to blood sugar.

Results suggested that consuming foods rich in monounsaturated fat or polyunsaturated fat had a positive effect on blood glucose control, compared with consumption of dietary carbohydrate or saturated fat.

For each five percent of dietary energy that was switched from carbohydrates or saturated fats to mono- or polyunsaturated fats, they found a drop of around 0.1 percent in HbA1c – a blood marker of long-term glucose control.Previous research has suggested that for each 0.1 percent decrease in HbA1c, the incidence of type 2 diabetes drops by 22 percent and the chance of developing cardiovascular diseases falls by 6.8 percent.

Imamura notes that replacing carbohydrates and saturated fats with polyunsaturated fats appears to be consistently beneficial.Imamura adds: “This is a positive message for the public. Don’t fear healthy fats.”This is the first time a team has systematically reviewed all the available evidence measuring the effects of carbohydrate and different kinds of fat in the diet.The authors hope that the results will help scientists, healthcare workers, and the public to set priorities that will help to combat the worldwide problem of type 2 diabetes.

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