Cholesterol: Friend Or Foe?
Written by Natasha Campbell-McBride, MD 2008-May-04
The art of medicine consists in amusing the patient while nature cures the disease. --Voltaire
In our modern world, cholesterol has become almost a swear word. Thanks to the promoters of the diet-heart hypothesis, everybody "knows" that cholesterol is "evil" and has to be fought at every turn. If you believe the popular media, you would think that there is simply no level of cholesterol low enough. If you are over a certain age, you are likely to be tested for how much cholesterol you have in your blood. If it is higher than about 200 mg/100ml (5.1 mol/l), you may be prescribed a "cholesterol pill." Millions of people around the world take these pills, thinking that this way they are taking good care of their health. What these people don’t realize is just how far from the truth they are. The truth is that we humans cannot live without cholesterol. Let us see why.
Our bodies are made out of billions of cells. Almost every cell produces cholesterol all the time during all of our lives. Why? Because every cell of every organ has cholesterol as a part of its structure. Cholesterol is an integral and very important part of our cell membranes, the membranes that enclose each of our cells, and also of the membranes surrounding all the organelles inside the cell. What is cholesterol doing there? A number of things.
First of all, saturated fats and cholesterol make the membranes of the cells firm—without them the cells would become flabby and fluid. If we humans didn’t have cholesterol and saturated fats in the membranes of our cells, we would look like giant worms or slugs. And we are not talking about a few molecules of cholesterol here and there. In many cells, almost half of the cell membrane is made from cholesterol. Different kinds of cells in the body need different amounts of cholesterol, depending on their function and purpose. If the cell is part of a protective barrier, it will have a lot of cholesterol in it to make it strong, sturdy and resistant to any invasion. If a cell or an organelle inside the cell needs to be soft and fluid, it will have less cholesterol in its structure.
This ability of cholesterol and saturated fats to firm up and reinforce the tissues in the body is used by our blood vessels, particularly those that have to withstand the high pressure and turbulence of the blood flow. These are usually large or medium arteries in places where they divide or bend. The flow of blood pounding through these arteries forces them to incorporate a layer of cholesterol and saturated fat in the membranes, which makes it stronger, tougher and more rigid. These layers of cholesterol and fat are called fatty streaks. They are completely normal and form in all of us, starting from birth and sometimes even before we are born. Various indigenous populations around the world, who never suffer from heart disease, have plenty of fatty streaks in their blood vessels in old and young, including children. Fatty streaks are not indicative of the disease called atherosclerosis.
All the cells in our bodies have to communicate with each other. How do they do that? They use proteins embedded into the membrane of the cell. How are these proteins fixed to the membrane? With the help of cholesterol and saturated fats! Cholesterol and stiff saturated fatty acids form so-called lipid rafts, which make little homes for every protein in the membrane and allow it to perform its functions. Without cholesterol and saturated fats, our cells would not be able to communicate with each other or to transport various molecules into and out of the cell. As a result, our bodies would not be able to function the way they do. The human brain is particularly rich in cholesterol: around 25 percent of all body cholesterol is accounted for by the brain. Every cell and every structure in the brain and the rest of our nervous system needs cholesterol, not only to build itself but also to accomplish its many functions. The developing brain and eyes of the fetus and a newborn infant require large amounts of cholesterol. If the fetus doesn’t get enough cholesterol during development, the child may be born with a congenital abnormality called cyclopean eye.1
Human breast milk provides a lot of cholesterol. Not only that, mother’s milk provides a specific enzyme to allow the baby’s digestive tract to absorb almost 100 percent of that cholesterol, because the developing brain and eyes of an infant require large amounts of it. Children deprived of cholesterol in infancy may end up with poor eyesight and brain function. Manufacturers of infant formulas are aware of this fact, but following the anti-cholesterol dogma, they produce formulas with virtually no cholesterol in them.
Vital Brain Matter
One of the most abundant materials in the brain and the rest of our nervous system is a fatty substance called myelin. Myelin coats every nerve cell and every nerve fiber like the insulating cover around electric wires. Apart from insulation, it provides nourishment and protection for every tiny structure in our brain and the rest of the nervous system. People who start losing their myelin develop a condition called multiple sclerosis. Well, 20 percent of myelin is cholesterol. If you start interfering with the body’s ability to produce cholesterol, you put the very structure of the brain and the rest of the nervous system under threat.
The synthesis of myelin in the brain is tightly connected with the synthesis of cholesterol. In my clinical experience, foods with high cholesterol and high animal fat content are an essential medicine for a person with multiple sclerosis. One of the most wonderful abilities we humans are blessed with is the ability to remember things—our human memory. How do we form memories? By our brain cells establishing connections with each other, called synapses. The more healthy synapses a person’s brain can make, the more mentally able and intelligent that person is. Scientists have discovered that synapse formation is almost entirely dependent on cholesterol, which is produced by the brain cells in a form called apolipoprotein E. Without the presence of this factor we cannot form synapses, and hence we would not be able to learn or remember anything. Memory loss is one of the side effects of cholesterol-lowering drugs.
In my clinic, I see growing numbers of people with memory loss who have been taking cholesterol- lowering pills. Dr Duane Graveline, MD, former NASA scientist and astronaut, suffered such memory loss while taking his cholesterol pill. He managed to save his memory by stopping the pill and eating lots of cholesterol-rich foods. Since then he has described his experience in his book, Lipitor: Thief of Memory, Statin Drugs and the Misguided War on Cholesterol. Dietary cholesterol in fresh eggs and other cholesterol-rich foods has been shown in scientific trials to improve memory in the elderly. In my clinical experience, any person with memory loss or learning problems needs to have plenty of these foods every single day in order to recover.
Necessary Product Of The Body
These foods give the body a hand in supplying cholesterol so it does not have to work as hard to produce its own. What a lot of people don’t realize is that most cholesterol in the body does not come from food! The body produces cholesterol as it is needed. Scientific studies have conclusively demonstrated that cholesterol from food has no effect whatsoever on the level of our blood cholesterol. Why? Because cholesterol is such an essential part of our human physiology that the body has very efficient mechanisms to keep blood cholesterol at a certain level.
When we eat more cholesterol, the body produces less; when we eat less cholesterol, the body produces more. As a raw material for making cholesterol the body can use carbohydrates, proteins and fats, which means that your pasta and bread can be used for making cholesterol in the body. It has been estimated that, in an average person, about 85 percent of blood cholesterol is produced by the body, while only 15 percent comes from food. So, even if you religiously follow a completely cholesterol-free diet, you will still have a lot of cholesterol in your body. However, cholesterol-lowering drugs are a completely different matter! They interfere with the body’s ability to produce cholesterol, and hence they do reduce the amount of cholesterol available for the body to use.
Dangers Of Low Cholesterol
If we do not take cholesterol-lowering drugs, most of us don’t have to worry about cholesterol. However, there are people whose bodies, for whatever reason, are unable to produce enough cholesterol. These people are prone to emotional instability and behavioral problems. Low blood cholesterol has been routinely recorded in criminals who have committed murder and other violent crimes, people with aggressive and violent personalities, people prone to suicide and people with aggressive social behavior and low self-control.
I would like to repeat what the late Oxford professor David Horrobin warned us about: "Reducing cholesterol in the population on a large scale could lead to a general shift to more violent patterns of behavior. Most of this increased violence would not result in death but in more aggression at work and in the family, more child abuse, more wife-beating and generally more unhappiness."
People whose bodies are unable to produce enough cholesterol do need to have plenty of foods rich in cholesterol in order to provide their organs with this essential-to-life substance.
What else does our body need all that cholesterol for?
After the brain, the organs hungriest for cholesterol are our endocrine glands: adrenals and sex glands. They produce steroid hormones. Steroid hormones in the body are made from cholesterol: testosterone, progesterone, pregnenolone, androsterone, estrone, estradiol, corticosterone, aldosterone and others. These hormones accomplish a myriad of functions in the body, from regulation of our metabolism, energy production, mineral assimilation, brain, muscle and bone formation to behavior, emotions and reproduction. In our stressful modern lives we consume a lot of these hormones, leading to a condition called "adrenal exhaustion." This condition is diagnosed very often by naturopaths and other health practitioners. There are many herbal preparations on the market for adrenal exhaustion. However, the most important therapeutic measure is to provide your adrenal glands with plenty of dietary cholesterol.
Without cholesterol we would not be able to have children because every sex hormone in our bodies is made from cholesterol. A fair percentage of our infertility epidemic can be laid at the doorstep of the diet-heart hypothesis. The more eager we became to fight animal fats and cholesterol, the more problems with normal sexual development, fertility and reproduction we started to face. About a third of western men and women are infertile, and increasing numbers of our youngsters are growing up with abnormalities in their sex hormones. These abnormalities lead to many physical problems.
Recent research has "discovered" that eating full-cream dairy products cures infertility in women.2 Researchers found that women who drink whole milk and eat high-fat dairy products are more fertile than those who stick to low-fat products. Study leader Dr Jorge Chavarro, of the Harvard School of Public Health, emphasized: "Women wanting to conceive should examine their diet. They should consider changing low-fat dairy foods for high-fat dairy foods, for instance by swapping skimmed milk for whole milk and eating cream, not low-fat yoghurt."
The Liver And Vitamin Regulation
One of the busiest organs in terms of cholesterol production in our bodies is the liver, which regulates the level of our blood cholesterol. The liver also puts a lot of cholesterol into bile production. Yes, bile is made out of cholesterol. Without bile we would not be able to digest and absorb fats and fat-soluble vitamins. Bile emulsifies fats; in other words, it mixes them with water, so that digestive enzymes can get to them. After it completes its mission, most of the bile gets reabsorbed in the digestive system and brought back to the liver for recycling. In fact, 95 percent of our bile is recycled because the building blocks of bile, one of which is cholesterol, are too precious for the body to waste. Nature doesn’t do anything without good reason. This example of the careful recycling of cholesterol alone should have given us a good idea about its importance for the body!
Bile is essential for absorbing fat-soluble vitamins: vitamin A, vitamin D, vitamin K and vitamin E. We cannot live without these vitamins. Apart from ensuring that fat-soluble vitamins get digested and absorbed properly, cholesterol is the major building block of one of these vitamins: vitamin D. Vitamin D is made from the cholesterol in our skin when it is exposed to sunlight. In those times of the year when there isn’t much sunlight, we can get this vitamin from cholesterol-rich foods: cod liver oil, fish, shellfish, butter, lard and egg yolks. Our recent misguided fears of the sun and avoidance of cholesterol-rich foods have created an epidemic of vitamin D deficiency in the Western world.
Unfortunately, apart from sunlight and cholesterol-rich foods there is no other appropriate way to get vitamin D. Of course, there are supplements, but most of them contain vitamin D2, which is made by irradiating mushrooms and other plants. This vitamin is not the same as the natural vitamin D. It does not work as effectively and it is easy to get a toxic level of it. In fact, almost all cases of vitamin D toxicity ever recorded were cases where this synthetic vitamin D2 had been used. Toxicity is almost impossible with natural vitamin D obtained from sunlight or cholesterol-rich foods because the body knows how to deal with an excess of natural substances. What the body does not know how to deal with is an excess of synthetic vitamin D2.
Vitamin D has been designed to work as a team with another fat-soluble vitamin: vitamin A. That is why foods rich in one tend to be rich in the other. So, by taking cod liver oil, for example, we can obtain both vitamins at the same time. As we grow older, our ability to produce vitamin D in the skin under sunlight is considerably diminished. Taking foods rich in vitamin D is therefore particularly important for older people. For the rest of us, sensible sunbathing is a wonderful, healthy and enjoyable way of getting a good supply of vitamin D.
Skin cancer, blamed on sunshine, is not caused by the sun. It is caused by trans fats from vegetable oils and margarine and other toxins stored in the skin. In addition, some of the sunscreens that people use contain chemicals that have been proven to cause skin cancer3.
Immune System Health
Cholesterol is essential for our immune system to function properly. Animal experiments and human studies have demonstrated that immune cells rely on cholesterol in fighting infections and repairing themselves after the fight. In addition, LDL-cholesterol (low-density lipoprotein cholesterol), the so-called "bad" cholesterol, directly binds and inactivates dangerous bacterial toxins, preventing them from doing any damage in the body. One of the most lethal toxins is produced by a widely spread bacterium, Staphylococcus aureus, which is the cause of MRSA (Methicillin- resistant Staphylococcus aureus), a common hospital infection. This toxin can literally dissolve red blood cells. However, it does not work in the presence of LDL-cholesterol. People who fall prey to this toxin have low blood cholesterol. It has been recorded that people with high levels of cholesterol are protected from infections; they are four times less likely to contract AIDS, they rarely get common colds and they recover from infections more quickly than people with "normal" or low blood cholesterol.
People with low blood cholesterol are prone to various infections, suffer from them longer and are more likely to die from an infection. A diet rich in cholesterol has been demonstrated to improve these people’s ability to recover from infections. So, any person suffering from an acute or chronic infection needs to eat high-cholesterol foods to recover. Cod liver oil, the richest source of cholesterol (after caviar), has long been prized as the best remedy for the immune system. Those familiar with old medical literature will tell you that until the discovery of antibiotics, a common cure for tuberculosis was a daily mixture of raw egg yolks and fresh cream.
Varying Blood Cholesterol Levels
The question is, why do some people have more cholesterol in their blood than others, and why can the same person have different levels of cholesterol at different times of the day? Why is our level of cholesterol different in different seasons of the year? In winter it goes up and in the summer it goes down. Why is it that blood cholesterol goes through the roof in people after any surgery? Why does blood cholesterol go up when we have an infection? Why does it go up after dental treatment? Why does it go up when we are under stress? And why does it become normal when we are relaxed and feel well? The answer to all these questions is this: cholesterol is a healing agent in the body. When the body has some healing jobs to do, it produces cholesterol and sends it to the site of the damage. Depending on the time of day, the weather, the season and our exposure to various environmental agents, the damage to various tissues in the body varies. As a result, the production of cholesterol in the body also varies.
Since cholesterol is usually discussed in the context of disease and atherosclerosis, let us look at the blood vessels. Their inside walls are covered by a layer of cells called the endothelium. Any damaging agent we are exposed to will finish up in our bloodstream, whether it is a toxic chemical, an infectious organism, a free radical or anything else. Once such an agent is in the blood, what is it going to attack first? The endothelium, of course. The endothelium immediately sends a message to the liver. Whenever our liver receives a signal that a wound has been inflicted upon the endothelium somewhere in our vascular system, it gets into gear and sends cholesterol to the site of the damage in a shuttle, called LDL-cholesterol. Because this cholesterol travels from the liver to the wound in the form of LDL, our "science," in its wisdom calls LDL "bad" cholesterol. When the wound heals and the cholesterol is removed, it travels back to the liver in the form of HDLcholesterol (high-density lipoprotein cholesterol). Because this cholesterol travels away from the artery back to the liver, our misguided "science" calls it "good" cholesterol. This is like calling an ambulance travelling from the hospital to the patient a "bad ambulance," and the one travelling from the patient back to the hospital a "good ambulance."
But the situation has gotten even more ridiculous. The latest thing that our science has "discovered" is that not all LDL-cholesterol is so bad. Most of it is actually good. So, now we are told to call that part of LDL the "good bad cholesterol" and the rest of it the "bad bad cholesterol."
Marvelous Healing Agent
Why does the liver send cholesterol to the site of the injury? Because the body cannot clear the infection, remove toxic elements or heal the wound without cholesterol and fats. Any healing involves the birth, growth and functioning of thousands of cells: immune cells, endothelial cells and many others. As these cells, to a considerable degree, are made out of cholesterol and fats, they cannot form and grow without a good supply of these substances. When the cells are damaged, they require cholesterol and fats to repair themselves. It is a scientific fact that any scar tissue in the body contains good amounts of cholesterol.4
Another scientific fact is that cholesterol acts as an antioxidant in the body, dealing with free radical damage.5 Any wound in the body contains plenty of free radicals because the immune cells use these highly reactive molecules for destroying microbes and toxins. Excess free radicals have to be neutralized, and cholesterol is one of the natural substances that accomplishes this function.
When we have surgery, our tissues are cut and many small arteries, veins and capillaries get damaged. The liver receives a very strong signal from this damage, so it floods the body with LDL-cholesterol to clean and heal every little wound in our blood vessels. That is why blood cholesterol goes high after any surgical procedure. After dental treatment, in addition to the damage to the tissues, a lot of bacteria from the tooth and the gums finish up in the blood, attacking the inside walls of our blood vessels. Once again, the liver gets a strong signal from that damage and produces lots of healing cholesterol to deal with it, so the blood cholesterol goes up.
The same thing happens when we have an infection: LDL-cholesterol goes up to deal with the bacterial or viral attack.
Apart from the endothelium, our immune cells need cholesterol to function and to heal themselves after the fight with the infection.
Our stress hormones are made out of cholesterol in the body. Stressful situations increase our blood cholesterol levels because cholesterol is being sent to the adrenal glands for stress hormone production. Apart from that, when we are under stress, a storm of free radicals and other damaging biochemical reactions occur in the blood. So the liver works hard to produce and send out as much cholesterol as possible to deal with the free radical attack. In situations like this, your blood cholesterol will test high. In short, when we have a high blood cholesterol level, it means that the body is dealing with some kind of damage. The last thing we should do is interfere with this process! When the damage has been dealt with, the blood cholesterol will naturally go down. If we have an ongoing disease in the body that constantly inflicts damage, then the blood cholesterol will be permanently high. So, when a doctor finds high cholesterol in a patient, what this doctor should do is to look for the reason. The doctor should ask, "What is damaging the body so that the liver has to produce all that cholesterol to deal with the damage?" Unfortunately, instead of this sensible procedure, our doctors are trained to attack the cholesterol.
Many natural herbs, antioxidants and vitamins have an ability to reduce our blood cholesterol. How do they do that? By helping the body remove the damaging agents, be they free radicals, bacteria, viruses or toxins. As a result, the liver does not have to produce so much cholesterol to deal with the damage. At the same time, vitamins, minerals, antioxidants, herbs and other natural remedies help to heal the wound. When the wound heals there is no need for high levels of cholesterol anymore, so the body removes it in the form of HDL-cholesterol or so-called "good" cholesterol. That is why herbs, vitamins, antioxidants and other natural remedies increase the level of HDL-cholesterol in the blood.
In conclusion, cholesterol is one of the most important substances in the body. We cannot live without it, let alone function well. The pernicious diet-heart hypothesis has vilified this essential substance. Unfortunately, this hypothesis has served many commercial and political interests far too well, so they ensure its long survival. However, the life of the diet-heart hypothesis is coming to an end as we become aware that cholesterol has been mistakenly blamed for the crime just because it was found at the scene.
Dietary Sources Of Cholesterol
Caviar is the richest source; it provides 588 mg of cholesterol per 100 grams. Obviously, this is not a common food for the majority of us, so let us have a look at the next item on the list.
Cod liver oil follows closely with 570 mg of cholesterol per 100 grams. There is no doubt that the cholesterol element of cod liver oil plays an important role in all the well-known health benefits of this time-honored health food.
Fresh egg yolk takes third place, with 424 mg of cholesterol per 100 gram. I would like to repeat: fresh egg yolk, not chemically mutilated egg powders (they contain chemically mutilated cholesterol)!
Butter provides a good 218 mg of cholesterol per 100 gram. We are talking about natural butter, not butter substitutes.
Cold-water fish and shellfish, such as salmon, sardines, mackerel and shrimps, provide good amounts of cholesterol, ranging from 173 mg to 81 mg per 100 gram. The proponents of low-cholesterol diets tell you to replace meats with fish. Obviously, they are not aware of the fact that fish is almost twice as rich in cholesterol as meat.
Lard provides 94 mg of cholesterol per 100 gram. Other animal fats follow.
Vitamin D Deficiency
What does it mean for our bodies to be deficient in vitamin D? A long list of suffering:
Diabetes, as vitamin D is essential for blood sugar control
Auto-immune illness, such as rheumatoid arthritis, lupus, inflammatory bowel disease and multiple sclerosis
Rickets and osteomalacia
Muscle weakness and poor neuro-muscular coordination
High blood pressure
Poor immunity and susceptibility to infections
Hyperparathyroidism, which manifests itself as osteoporosis, kidney stones, depression, aches and pains, chronic fatigue, muscle weakness and digestive abnormalities
Strauss E. One-eyed animals implicate cholesterol in development. Science. 1998 Jun 5;280(5369):1528-9.
Chavarro JI and others. A prospective study of dairy foods intake and anovulatory infertility. Human Reproduction, Issue 28, Feb 2007.
According to one theory, trans fats interfere in the metabolism of omega-3 fats, making them ineffective in producing their derivative eicosanoids, which leads to many types of cancers, including skin cancer. Trans fats also interfere with enzyme systems that help protect the body against cancer. References for the relationship of trans fats to skin cancer include:
Alberts et al. Molecular Biology of the Cell: fourth edition, NY: Garland Science, 2002; _An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation._
Cancer. 2002 Mar 15;94(6):1867-75; _Beneficial effects of sun exposure on cancer mortality._
Prev Med. 1993 Jan;22(1):132-40.
Review; Berg JM, Tymoczko JL and Stryer L. Biochemistry, 2006; _Does sunlight prevent cancer? A systematic review._
Eur J Cancer. 2006 Sep;42(14):2222-32. Epub 2006 Aug 10. Review; _Does sunlight have a beneficial influence on certain cancers?_
Prog Biophys Mol Biol. 2006 Sep;92(1):132-9. Epub 2006 Feb 28. Revew; _Ecologic studies of solar UVB radiation and cancer mortality rates._
Recent Results Cancer Res. 2003;164:371-7. Review; _Geographic patterns of prostate cancer mortality. Evidence for a protective effect of ultraviolet radiation._
Cancer. 1992 Dec 15;70(12):2861-9; Skrabanek P, McCormick J. Follies and fallacies in medicine.
Tarragon Press, Glasgow, 1989; _Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease._
Am J Clin Nutr. 2004 Dec;80(6 Suppl):1678S-88S. Review; _UV radiation and cancer prevention: what is the evidence?_
Anticancer Res. 2006 Jul–Aug;26(4A):2723-7. Review; _Vitamin D and cancer._
Anticancer Res. 2006 Jul-Aug;26(4A):2515-24. Review; Epstein SS. Unreasonable risk. 2001. Published by
Environmental Toxicology, PO Box 11170, Chicago, USA.
Pfohl M and others. Upregulation of cholesterol synthesis after acute myocardial infarction--is cholesterol a positive acute phase reactant? Atherosclerosis. 1999 Feb;142(2):389-93.
Enig, MG. Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol. Bethesda Press, Silver Spring, MD, 2000.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Fall 2007.
About the Author
Natasha Campbell-McBride, MD, MMedSci (neurology), MMedSci (nutrition), graduated with honors as a medical doctor in 1984 from Bashkir Medical University in Russia. In the following years she gained a postgraduate degree in neurology.After practicing for five years as a neurologist and three years as a neurosurgeon, she started a family and moved to the UK. Fairly shortly after that her son was diagnosed autistic, which prompted an intensive study into causes and treatments of autism. It was during this time that Dr. Campbell-McBride developed her theories on the relationship between neurological disorders and nutrition. She then completed a second postgraduate degree in human nutrition at Sheffield University, UK.
Having successfully treated her son, Dr. Campbell-McBride has returned to practice in 2000 and runs the Cambridge Nutrition Clinic. She has specialized in using nutritional approach as a treatment, and has become recognized as one of the world’s leading experts in treating children and adults with learning disabilities and other mental disorders, as well as children and adults with digestive and immune disorders.
In 2004 she has published Gut and Psychology Syndrome: Natural Treatment Of Autism, ADHD, Dyslexia, Dyspraxia, Depression and Schizophrenia, in which she explores the connection between the patient's physical state and brain function. The book gives full details of the GAPS Nutritional Protocol, highly successful in treating patients with learning disabilities and other mental problems.
In her clinic, Dr Campbell-McBride works with many patients suffering from heart disease, high blood pressure, arrhythmia, stroke and other complications of atherosclerosis. She has become acutely aware of the existing confusion about nutrition and these conditions, which spurred an intensive study into this subject. The result of this study is her new book Put You Heart In Your Mouth! What Really Is Heart Disease and What We Can Do To Prevent and Even Reverse It.
Dr Campbell-McBride is a keynote speaker at many professional conferences and seminars around the world. She frequently gives talks to health practitioners, patient groups and associations. She is a member of the Society of Authors and a regular contributing health editor to a number of magazines and newsletters.