How Fat Moves From Food To The Bloodstream
Fat and cholesterol cant dissolve in water or blood. Instead, the body packages fat and cholesterol into tiny, protein-covered particles called lipoproteins. Lipoproteins can transport a lot of fat they mix easily with blood and flow with it. Some of these particles are big and fluffy, while others are small and dense. The most important ones are low-density lipoproteins , high-density lipoproteins , and triglycerides.
- Low Density lipoproteins
Low-density lipoproteins carry cholesterol from the liver to the rest of the body. Cells latch onto these particles and extract fat and cholesterol from them. When there is too much LDL cholesterol in the blood, these particles can form deposits in the walls of the coronary arteries and other arteries throughout the body. Such deposits, called plaque, can narrow arteries and limit blood flow. When plaque breaks apart, it can cause a heart attack or stroke. Because of this, LDL cholesterol is often referred to as bad, or harmful, cholesterol.
- High-density lipoproteins
High-density lipoproteins scavenge cholesterol from the bloodstream, from LDL, and from artery walls and ferry it back to the liver for disposal. Think of HDL as the garbage trucks of the bloodstream. HDL cholesterol is often referred to as good, or protective, cholesterol.
In general, the lower your LDL and the higher your HDL, the better your chances of preventing heart disease and other chronic conditions.
Plant Sterols Can Lower Cholesterol Levels
Plant sterols are found naturally in plant foods including sunflower and canola seeds, vegetable oils and in nuts, legumes, cereals, fruit and vegetables. Some margarine and milks have concentrated plant sterols added to them. Margarines enriched with plant sterolslower LDL cholesterol in most people if the correct amount is eaten .
How Is High Cholesterol Diagnosed
There are usually no signs or symptoms that you have high cholesterol. There is a blood test to measure your cholesterol level. When and how often you should get this test depends on your age, risk factors, and family history. The general recommendations are:
For people who are age 19 or younger::
- The first test should be between ages 9 to 11
- Children should have the test again every 5 years
- Some children may have this test starting at age 2 if there is a family history of high blood cholesterol, heart attack, or stroke
For people who are age 20 or older::
- Younger adults should have the test every 5 years
- Men ages 45 to 65 and women ages 55 to 65 should have it every 1 to 2 years
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How Low Is Too Low
Cholesterol that is too low is bad for the brain. Whats considered normal? Normal total cholesterol levels are 135-200 mg/dL. However, be aware that several studies show that lowering total cholesterol levels below 160 mg/dL can increase the risk of depression, suicide, and homicide, so 160-200 mg/dL is optimal. Dont go too low.
Surprisingly, if you have cholesterol on the higher side of the healthy range later in life it could improve your cognitive performance, according to research in Psychosomatic Medicine. In fact, findings in the journal Neurology show that having higher levels of total cholesterol later in life decreases your risk of dementia.
According to Dr. Bowden, the typical cholesterol tests that simply measure total cholesterol, HDL, LDL, and triglycerides are obsolete, and theyre missing the most important numbers that matter for heart health. Whats important to understand is that cholesterol doesnt travel in the blood. Cholesterol has to be in a container, he says. Those containers are the lipoprotein. Lipoprotein is the ship cholesterol is the cargo. Its the number of boats in the water thats important, not the cargo.
When having your cholesterol levels tested, ask your healthcare professional to also test your lipoproteins and the particle size of your LDL cholesterol because larger particles are less toxic than smaller ones. If you want to find out more about cholesterol, read the revised and expanded editions of The Great Cholesterol Myth.
Cholesterol’s Effects On Cellular Membranes
- Virginia Tech
- New findings have far-reaching implications in the general understanding of disease, the design of drug delivery methods, and many other biological applications that require specific assumptions about the role of cholesterol in cell membranes.
For more than a decade, scientists have accepted that cholesterol — a key component of cell membranes — did not uniformly affect membranes of different types. But a new study led by Assistant Professor Rana Ashkar of the Virginia Tech Department of Physics finds that cholesterol actually does adhere to biophysical principles.
The findings, published recently in the Proceedings of the National Academy of Sciences, have far-reaching implications in the general understanding of disease, the design of drug delivery methods, and many other biological applications that require specific assumptions about the role of cholesterol in cell membranes.
“Cholesterol is known to promote tighter molecular packing in cell membranes, but reports about how it stiffens membranes have been so conflicting,” said Ashkar, who is a faculty member in the Virginia Tech College of Science. “In this work, we show that, at the nanoscale level, cholesterol indeed causes membrane stiffening, as predicted by physical laws. These findings affect our understanding of the biological function of cholesterol and its role in health and disease.”
Cholesterol’s impact on cell membranes at the molecular level
Proving her point
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Why Dietary Cholesterol Does Not Matter
High blood cholesterol levels are a known risk factor for heart disease.
For decades, people have been told that the dietary cholesterol in foods raises blood cholesterol levels and causes heart disease.
This idea may have been a rational conclusion based on the available science 50 years ago, but better, more recent evidence doesnt support it.
This article takes a close look at the current research on dietary cholesterol and the role it plays in blood cholesterol levels and heart disease.
What Is A Healthy Blood Cholesterol Level
For people who have plaque in their arteries or who have other factors that put them at risk for cardiovascular disease, doctors recommend an ideal LDL level well below 70 mg/dl. For those without risk factors who have an LDL level at or above 190 mg/dl, the recommendation is to get this level down to below 100 mg/dl. People age 40 to 75 who are living with diabetes and whose LDL is at 70 or above may need medication.
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Myth: Eating Foods With A Lot Of Cholesterol Will Not Make My Cholesterol Levels Go Up
Fact: It can be complicated. We know that foods with a lot of cholesterol usually also have a lot of saturated fat. Saturated fats can make your cholesterol numbers higher, so its best to choose foods that are lower in saturated fats. Foods made from animals, including red meat, butter, and cheese, have a lot of saturated fats.
Instead, aim to eat foods with plenty of fiber, such as oatmeal and beans, and healthy unsaturated fats, such as avocados, olive oil, and nuts. Learn more about healthy diets and nutrition at CDCs nutrition, physical activity, and obesity website.
Talk with your health care provider about ways to manage your cholesterol. Learn more about medicines to lower cholesterol.
The Difference Between Good And Bad Cholesterol
If cholesterol is so necessary, why is it sometimes described as “bad” and at other times as “good?”
Your liver packages cholesterol into so-called lipoproteins, which are combinations of lipids and proteins. Lipoproteins operate like commuter buses that carry cholesterol, other lipids like triglycerides, fat-soluble vitamins, and other substances through the bloodstream to the cells that need them.
- Low-density lipoproteins, sometimes called bad cholesterol, gets its bad reputation from the fact that high levels of it are associated with increasing your risk of heart disease. LDL contains more cholesterol than protein, making it lighter in weight. LDL travels through the bloodstream and carries cholesterol to cells that need it. When it becomes oxidized, LDL can promote inflammation and force lipids to accumulate on the walls of vessels in the heart and rest of the body, forming plaques. These plaques can thicken and may limit or completely block blood and nutrients to affected tissues or organs.
- HDLor high-density lipoproteinsis also commonly referred to as “good cholesterol.” HDL is heavier than LDL because it contains more protein and less cholesterol. HDL gets its good reputation from the fact that it takes cholesterol from the cells and brings it to the liver. Having higher levels of HDL may also help lower your risk of developing cardiovascular disease.
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How Fat And Cholesterol In Food Affect Blood Cholesterol Levels
The types of fat in the diet help determine the amount of total, HDL, and LDL cholesterol in the bloodstream. The types and amount of carbohydrate in the diet also play a role. Cholesterol in food matters, too, but not nearly as much.
- The discovery half a century ago that high blood cholesterol levels were strongly associated with an increased risk for heart disease triggered numerous warnings to avoid foods that contain cholesterol, especially eggs and liver. However, scientific studies show a weak relationship between the amount of cholesterol a person consumes and his or her blood cholesterol levels
- In studies of more than 80,000 female nurses, Harvard researchers found that consuming about an egg a day was not associated with higher risk of heart disease. However, people who have heart disease or diabetes should monitor egg consumption.
For most people, the amount of cholesterol eaten has only a modest impact on the amount of cholesterol circulating in the blood. For some people, though, blood cholesterol levels rise and fall very strongly in relation to the amount of cholesterol eaten. For these responders, avoiding cholesterol-rich foods can have a substantial effect on blood cholesterol levels. Unfortunately, at this point there is no way other than by trial and error to identify responders from non-responders to dietary cholesterol.
Other Functions Of Cholesterol
Vertebrates rely heavily on cholesterol for the digestion of fats. Cholesterol is a molecule that is made in the liver cells, and it is a precursor molecule used to manufacture bile acids. The bile acids are an essential part of the digestive process.
In humans, bile is produced in the liver and stored in the gallbladder. When a person eats something with fat in, the gallbladder contracts to squeeze bile into the small intestine where it helps to break down the large lipid molecules.
This then makes the role of the lipase enzyme easier by providing an increased surface area for the digestion of the fats into smaller molecules.
Cholesterol is also a precursor molecule of many of the steroid hormones including, for instance, estrogen and testosterone.
Cholecalciferol or vitamin D3 is manufactured in the skin from cholesterol molecules in the presence of sunlight. This is an important vitamin that we need to have in our bodies for healthy functioning.
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The Functions Of Cholesterol
Before looking at how cholesterol can be lowered, it is important to understand what it is. Cholesterol is a waxy like substance produced by the liver. Although Cholesterol is often considered a bad thing, there is a bright side to it as well. Cholesterol is important to your overall health and body functions. It is an important ingredient and helps in the growth of cell membrane and producing hormones and many other bodily functions. All the cells in the body are formed in varying degrees from cholesterol. Elevated levels of cholesterol could prove to be dangerous as it leads to more complicated cardiac problems.
Cholesterol works to repair cell membranes and produces hormones like estrogen and testosterone and bile acid which are proved to help in the digestion of fat.
If you have too much cholesterol in your body, the levels build-up in the blood and cause clogging of the arteries called atherosclerosis, which in turn raises the risk for heart disease and/or stroke.
Cholesterol is produced in your body while eating saturated foods made from animal-based foods such as dairy meat, eggs, which are essential components in the elevation of cholesterol. Fruits, vegetables, and grains do not contain cholesterol.
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Cholesterol In Health And Disease
Department of Medicine, and Department of Anatomy and Cell Biology, Columbia University, New York, New York, USA
Address correspondence to: Ira Tabas, Department of Medicine, Columbia University, 630 West 168th Street, New York, New York 10032, USA. Phone: 305-9430 Fax: 305-4834 E-mail: .
J Clin Invest.
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Effects Of High Cholesterol Levels
The liver is the main processing centre for cholesterol and dietary fat. When we eat animal fats, the liver transports the fat, together with cholesterol in the form of lipoproteins, into our bloodstream.
Too much cholesterol circulating within LDL in our bloodstream leads to fatty deposits developing in the arteries. This causes the vessels to narrow and they can eventually become blocked. This can lead to heart disease and stroke.
What Factors Affect Cholesterol Levels In Your Blood
Factors Affecting Blood Cholesterol Levels
- Heredity Your genes partly determine the amount of cholesterol your body makes, and high blood cholesterol can run in families.
- Diet There are two nutrients in the foods you eat that can increase your blood cholesterol level: saturated fat and cholesterol.
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Medication May Be Needed
For some people, diet and lifestyle changes are not enough. High blood cholesterol levels often have a genetic component. Some people inherit altered genes that cause high cholesterol and this cannot usually be changed sufficiently by lifestyle or diet.
If you are at risk of coronary heart disease and your LDL cholesterol level doesnt drop after scrupulous attention to diet, your doctor may recommend medications to force your blood LDL levels down. Cell cholesterol levels, however, remain normal, so lowering blood cholesterol has no effect on most cell metabolic processes.
Some people get muscle aches from statins, which are the most commonly used medication to lower blood cholesterol. However, diet and exercise will still be important, even if you are taking medication. Your doctor may also refer you to a specialist who treats cardiovascular disease.
Metabolism Recycling And Excretion
Cholesterol is susceptible to oxidation and easily forms oxygenated derivatives called oxysterols. Three different mechanisms can form these: autoxidation, secondary oxidation to lipid peroxidation, and cholesterol-metabolizing enzyme oxidation. A great interest in oxysterols arose when they were shown to exert inhibitory actions on cholesterol biosynthesis. This finding became known as the “oxysterol hypothesis”. Additional roles for oxysterols in human physiology include their participation in bile acid biosynthesis, function as transport forms of cholesterol, and regulation of gene transcription.
In biochemical experiments radiolabelled forms of cholesterol, such as tritiated-cholesterol are used. These derivatives undergo degradation upon storage and it is essential to purify cholesterol prior to use. Cholesterol can be purified using small Sephadex LH-20 columns.
Although cholesterol is a steroid generally associated with mammals, the human pathogen Mycobacterium tuberculosis is able to completely degrade this molecule and contains a large number of genes that are regulated by its presence. Many of these cholesterol-regulated genes are homologues of fatty acid-oxidation genes, but have evolved in such a way as to bind large steroid substrates like cholesterol.
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What Treatments Are Available For High Cholesterol
Treatment may include:
Addressing risk factors. Some risk factors that can be changed include lack of exercise and poor eating habits.
Cholesterol-lowering medicines. Medicines are used to lower fats in the blood, particularly LDL cholesterol. Statins are a group of medicines that can do this. The two most effective types are atorvastatin and rosuvastatin. Other medicines that lower cholesterol levels are ezetimibe and PCSK9 inhibitors.
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Checking Your Blood Cholesterol Level
A cholesterol screening is an overall look at the fats in your blood. Screenings help identify your risk for heart disease. It is important to have what is called a full lipid profile to show the actual levels of each type of fat in your blood: LDL, HDL, triglycerides, and others. Talk with your healthcare provider about when to have this test.
What’s Cholesterol Doing In There
Although cholesterol tends to get a bad rap, it also performs several important functions in the body:
- It plays a role in forming and maintaining cell membranes and structures. Cholesterol can insert between fat molecules making up the cell, making the membrane more fluid. Cells also need cholesterol to help them adjust to changes in temperature.
- Cholesterol is essential for making a number of critical hormones, including the stress hormone cortisol. Cholesterol is also used to make the sex hormones testosterone, progesterone, and estrogen.
- The liver also uses cholesterol to make bile, a fluid that plays a vital role in the processing and digestion of fats.
- Cholesterol is used by nerve cells for insulation.
- Your body also needs cholesterol to make vitamin D. In the presence of sunlight, cholesterol is converted into vitamin D.
What To Feed Your Brain
Low-fat diets are not good for your brain. Focus on healthy fats, such as avocados, nuts, seeds, and sustainable, clean fish. Fat is not the enemy. Good dietary fats are essential to your brain health. For example, omega-3 fatty acids have been found to reduce symptoms of depression.
In a study from the Mayo Clinic, people who ate a fat-based diet had a 42% lower risk of developing Alzheimers disease those who ate a protein-based diet had a 21% percent lower risk of developing Alzheimers but those who ate a simple carbohydrate-based diet had a 400% percent increased risk of developing Alzheimers. Its the sugar, and foods that turn to sugar, not the fat, thats the problem.
However, not all fats are equal. Avoid trans fats , which are associated with an increase in depression. Also skip fats that are higher in omega-6 fatty acids, such as many refined vegetable oils, which are associated with an increase in inflammation, which also has negative effects on brain health.
Memory problems, brain fog, depression, and other mental and cognitive health issues cant wait. During these uncertain times, your mental well-being is more important than ever and waiting until life gets back to normal is likely to make your symptoms worsen over time.
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