The Whole Cholesterol Story
We've all heard about cholesterol - that evil waxy substance gunking up our arteries, but did you know that despite efforts to reduce saturated fats and cholesterol in our diet, heart disease is still one of the leading killers of men and women worldwide?
Cholesterol, although sometimes considered a bad guy, is actually vital to life. Studies show that having low cholesterol as we get older actually may increase risk of cognitive decline, depression and suicide (in men).
What does cholesterol actually do?
1. Cell membranes - Cholesterol is essential in keeping the membranes of cells from becoming too rigid or fluid. Like Goldilocks, we don't want cells that are too soft and squishy (unable to keep their shape) or too hard and rigid (which may interfere with cell function). Cells communicate through receptors and proteins in their membranes. Without cholesterol to anchor these receptors and proteins (in nifty gadgets called “lipid rafts”), cells couldn’t talk to one another. Cell to cell communication is one of the most important aspects of overall health, when communication breaks down, eventually pathology ensues.
2. Hormones - Cholesterol is the raw material from which the body makes sex hormones like estrogen, progesterone and testosterone. Aldosterone (regulates salt balance in the body) and cortisone/cortisol are also made from cholesterol. These steroid hormones have hundreds of important functions in the body. Women, whose total cholesterol fall below 160 mg/dl may have trouble with fertility and menstrual cycles as they may not have sufficient starting material from which to make hormones. As men age, if their cholesterol gets too low (usually the result of statin drug therapy), they may begin to feel depressed, lack drive and have issues in the bedroom, as they no longer have adequate starting material to make the hormone testosterone.
3. Vitamin D - Vitamin D is also made from cholesterol. It has important immune enhancing properties. Vitamin D is made when cholesterol in the skin reacts with UV light. Tip - most people require a minimum of 15-20 minutes of natural sunlight (without sunscreen), on a large part of their bodies daily, in order to maintain healthy vitamin D levels. If your Vitamin D level is under 70 ng/ml consider spending more time outside, supplementing Vitamin D, or testing your genetic ability to use and metabolize vitamin D.
4. Myelin, nervous system and the brain - Myelin is akin to the plastic covering on wires and the wires can be thought of like nerves. This important fat based insulating material is essential for signal and electrical conduction throughout the nervous system. Without myelin to cover neurons (nerve cells) the signal transmission would be too slow, and we would experience spasticity or issues with muscular. It is essential to proper nervous system functioning.
5. Fixing stuff – cholesterol is needed to help repair damage in the body. In order to make new cells, their membranes require cholesterol. That’s why when you have surgery, get injured or are stressed cholesterol levels in the blood increase.
6. Cholesterol is a powerful antioxidant - We have all heard about the antioxidants in berries, dark green vegetables and other foods – but cholesterol an antioxidant? Cholesterol has been shown to come to the rescue of cells damaged by free radicals and help repair damage done to the arteries.
So now we have an idea about why cholesterol is so important- why is it considered such a villain in the fight against heart disease?
Well, the simplified idea is that because LDL is the shuttle that takes cholesterol from the liver to damaged cells and HDL picks up cholesterol to bring it back to the liver; LDL is BAD and HDL is GOOD.
Arterial plaques begin when something damages blood vessel walls. LDL comes in to try and help, depositing cholesterol at the site of injury. However this is where it gets a bit complicated. LDL comes in different sizes. Big LDL particles cannot get into the artery wall to contribute to plaques. They are nice and fluffy and bounce around happily. Small ones can, but the catch is they are also (because of their composition) very delicate and prone to damage.
These small LDL’s that squeeze into the site of injury in a vessel wall and are damaged by the immune system crossfire known as oxidation (we will refer to these as oxidized LDL-oxLDL). Once LDL is damaged it looks very different to the body, and the immune system goes on the attack against these strange arterial invaders (are they native? bacteria? what the heck, definitely don't look like normal cholesterol!). The immune system on seeing these oxLDL molecules, calls in more and more immune cells to stop the "invasion" by this weird foreign looking cholesterol. This sets the stage for more and more inflammation and immune activation, and its exactly this, that lies at the root of heart disease. Arterial plaques continue to grow as immune cells consume cholesterol to become fatty foam cells. This is the process that leads to the narrowing of arteries, blood clots and cardiovascular complications.
To recap; the real problem here is not cholesterol alone, it's damaged and small LDL molecules and inflammation and things that trigger damage to the arterial walls. Things that damage the arteries include, high blood pressure, inflammation, high blood sugar, infections and toxicity (such as heavy metals-mercury and lead), and there are a variety of dietary, genetic and lifestyle factors that predispose people to making more of that funky-looking small or oxidized LDL.
Cholesterol is found at the scene of the crime, but is not the actual villain!!
Make sure to check out the next blog post, on how we can keep our cholesterol healthy and reduce our risk of heart disease.