“What should I do about my high cholesterol?” I was asked. I shall try to present an unbiased, evidence-based answer. I outline the main research, with linked references to look at, if you have time. I summarise what you need to know about cholesterol and its involvement in atherosclerosis, but please bear in mind that it’s not the whole story to cardiovascular disease management. I offer some private testing choices and non-pharmaceutical approaches to optimising healthy levels. If time is tight, just scan through the sub-titles to find the section you are most interested in.
You are probably aware of the mainstream medical view, the lipid hypothesis. It says that raised cholesterol is a primary cause of atherosclerosis (plaque deposits blocking the arteries) and cardiovascular disease. This originated from research by Ancel Keys and The Framingham Heart Study. A review of the history can be found here. Subsequently, there has been lot of published evidence affirming the relationship between low-density lipoprotein cholesterol (LDL-C) and cardiovascular disease. This is why doctors prescribe statins, which reduce LDL-C production by the liver.
However, some have challenged this perhaps over-simplistic view. In 2016 a meta-analysis was published in the British Medical Journal. It concluded that although there was an association (note – an “association” cannot say that it “causes” something) between total cholesterol and cardiovascular death, the risk actually decreased with age and became minimal after the age of 80. This finding is inconsistent with the lipid hypothesis (i.e. that LDL-C causes atherosclerosis).
Another turn around was in 2015, when the US dietary guidelines advisory committee reviewed all the research over the past 40 years and concluded that we should not be concerned about dietary cholesterol, arguing that it “is not a nutrient of concern”. They simultaneously lifted any previous recommendation to limit dietary cholesterol in our diets.
So, yes… the highly nutritious egg, once vilified, is now considered safe to consume.
What is cholesterol? Why do we need it?
Cholesterol is a fat molecule that’s found in every cell of the body. It is an essential part of our cell membranes, where it controls the movement of molecules into and out of the cell. It forms the chemical backbone of our adrenal hormones; sex hormones and vitamin D. Bile salts, made in the liver are also made of cholesterol. Bile salts help us emulsify (break down) fats into smaller absorbable molecules. It is said that we make approximately 75% of our own cholesterol in the liver and intestines. If dietary intake is low, our body makes more and dietary intake is high, the body makes less.
What are LDL-C and HDL-C?
Cholesterol molecules come in different shapes and sizes. They are carried in our bloodstreams by carrier proteins, because being a fat-soluble substance; cholesterol can’t mix with water in the bloodstream. The cholesterol molecules, together with their carrier proteins are called lipoproteins (meaning molecules of fat and protein). You will have heard of two (of 5) kinds of lipoproteins: low-density lipoproteins (LDL) and high-density lipoproteins (HDL). I am not going to call them “good” or “bad”, because scientists no longer think it’s that simple.
Cholesterol molecules can also be classified by their size, small and dense or large and fluffy. Some scientists believe that the small, dense LDL-C molecules are more damaging to our artery walls because they are small enough to squeeze through the artery walls and get lodged there. However, contrary to this, other doctors, like Dr. Malcolm Kendrick, argue that the LDL-C molecules are present as part of the arterial repair process, and they are not the actual cause at all. HDL cholesterol has gained interest as a more cardio protective molecule, but more research is still needed, as much is still under debate. Also, measuring molecule size has not been widely accepted in clinical practice yet.
Triglycerides and phospholipids are again molecules of fat in the bloodstream, which can either be burned for energy or stored as fat. They are often measured alongside cholesterol.
Cholesterol’s role in damaging the artery
Dr. John Campbell, cardiologist, describes the mainstream view of the cellular mechanisms of atherosclerosis in this Youtube video (48 mins).
It is believed that the body uses cholesterol like a “protective plaster” to the everyday normal chemical and physical damage that happens in the inner lining of our arteries as millions of blood cells, proteins and other molecules rush along. The body tries to repair this damage by laying down a protective layer of fat (cholesterol). This would seem like a good solution, but over time, the cholesterol can become oxidised, and this is where the trouble starts. One study reported that oxidized cholesterol was the strongest predictor of coronary artery events, compared to a conventional lipid panel test.
So, oxidised cholesterol is perceived by the body to be a foreign molecule, which needs to be removed. In response, the immune system brings in white blood cells called macrophages, to engulf or consume the oxidised cholesterol. In so doing, the macrophages become swollen cholesterol-laden “foam cells”. At this stage, we can see the fatty streaks under the microscope. Once full, the foam cells send out chemical SOS messages (cytokines) and the inflammatory response is initiated. The cytokine-mediated inflammation in the artery wall then triggers smooth muscle cells in the inner artery wall to produce collagen to help sure up the damage. This plaque gets ever bigger until it eventually ruptures, leading to the formation of a blood clot (thrombus), which can later block an artery and cause a heart attack. The diagram below illustrates this.
Formation of atherosclerosis
What determines the levels of cholesterol in our bloodstream?
The regulation of cholesterol in our body is a complex – believe me! Cell membrane receptors, enzyme feedback mechanisms and genetic factors all play a part. This heavyweight paper in 2002 states that there are over “30 genes dedicated to the synthesis and uptake of cholesterol, fatty acids, triglycerides and phospholipids”. More research is needed into how and why some of these control mechanisms may go awry.
High cholesterol has no symptoms. Taking a cholesterol test is therefore a logical place to start. A standard lipid panel includes total cholesterol, LDL-C, HDL-C and triglycerides. From these, you can calculate your lipid ratios, which also helps to assess your risk. Please be aware that reference ranges for optimum levels vary between different published sources. Heart UK – the cholesterol charity, gives the following ranges:
- Total Cholesterol (TC) – Ideally, 5 mmol/L or less (this is currently disputed)
- LDL-Cholesterol (LDL-C) – ideally, 3 mmol/L or less
- HDL-Cholesterol (HDL-C) – ideally, over 1mmol/L (men), over 1.2mmol/L (women).
- TC:HDL ratio – TC divided by HDL-C. > 6 is considered high risk – the lower the better.
- Triglyceride (TG) – Ideally, below 2.0 mmol/L (others say 1.7) on a fasting sample.
A straightforward home test (same as your GP would do) can now be performed with a finger prick test, Thriva’s Lifestyle test, which is £39. Alternatively, you can buy your own home self-testing kit for regular monitoring.
At the top end of the private testing market you will find Genova Diagnostics CV Health test. You might consider this test if you have a family history of heart disease, know that you have abnormal blood lipids, have obesity and/or diabetes, smoke and are physically inactive. Using state of the art technology, this comprehensive test measures a range of cardiovascular health markers (not just cholesterol). It measures the size and density of the cholesterol molecules, other important lipoproteins and inflammatory markers, homocysteine, fibrinogen and an insulin resistance score. This costs £240 and requires a full blood sample to be taken. Please don’t expect to get this on the NHS.
In addition, and particularly if you are overweight, have diabetes or metabolic syndrome you would be wise to ask your GP to test your fasting insulin level and fasting blood glucose level (normal is 4.0-5.9mmol/L), because both are indicators for heart disease.
The National Institute for Health and Care Excellence (NICE) guidelines state that improving diet and lifestyle should be considered for primary prevention, before statin treatment commences. They also acknowledge that people may well need help in making those changes. Ask me, your Nutritional Therapist or Mother Nature’s Diet. Here are some researched suggestions:
Foods to avoid and why
- Avoid hydrogenated and trans fats found in most processed foods, margarine, baked goods, fried foods, sauces and salad dressings. Read here and here for more information.
- Avoid refined plant oils – high in omega 6 fats. I know, against all the advice we were told two decades ago. So don’t use refined vegetable oil, sunflower oil, corn oil and rapeseed oil. Omega 6 fats are linked to an increased risk of death among patients with heart disease, according to a 2013 British Medical Journal study.
- Avoid oxidized cholesterol. Cholesterol can be oxidized outside and inside our bodies. So it makes sense, at least, to avoid oxidized cholesterol in food. This hamster study demonstrated that oxidized cholesterol was more atherogenic than non-oxidized cholesterol. Avoid factors known to oxidise cholesterol (make it go rancid) such as commercially cooked and refrigerated meats (this means processed meats, such as smoked sausages and formed luncheon meats), deep fried foods, charring or frying at high temperatures, sunlight, microwave radiation. Keep animal foods in the dark, sealed from the air and in the fridge. Cook them gently and slowly. Don’t brown them or burn them – like they’ve been advising in the news recently.
- Avoid highly refined carbohydrate foods, such as biscuits, cakes, pastry, sweets, crisps etc. which raise blood sugar (hyperglycemia). When blood sugar is high, insulin will rise and in turn this causes a rise in triglycerides. The same applies to large amounts of fructose (from fruit juices) and high-fructose corn syrup in processed foods – both increase your body’s triglyceride levels, lower HDL-C and raise LDL-C. We do now know that low-carbohydrate diets (compared with low-fat diets) improve insulin resistance, HDL-C, LDL-C, particle size and particle number. Equally importantly, low-carbohydrate diets reduce inflammation.
Foods to eat and why
- Eat plenty of polyphenols, which have antioxidant properties. These food help to reduce cholesterol oxidation that takes place in our bodies. Some of the richest sources are cloves, dried peppermint, star anise, cocoa powder, dried oregano, celery seeds, dark chocolate (yay!), flaxseeds, elderberries, blackcurrants, chestnuts, black olives.
- Use coconut oil, grass-fed butter or olive oil for frying & roasting because they are high in monosaturated or saturated fats and therefore more stable at higher temperatures and less likely to oxidize.
- Eat mixed nuts (one handful every day) and extra virgin olive oil drizzled over salads and vegetables. Both foods help to reduce plaque formation and dilate blood vessels.
- Eat foods high in soluble fibre because it helps reduce cholesterol absorption from the intestine. Try oats, psyllium (a fibre supplement), flaxseeds, vegetables, apples & pears, beans & lentils, nuts & seeds. Soluble fibre also decreases systolic and diastolic blood pressure. Aim for 25-40g/day.
- Eat foods high in natural plant sterols (2g/day). They are found in fruit and vegetables, e.g. whole grains, legumes, nuts and seeds. Sterols have a chemical structure similar to cholesterol and therefore compete with cholesterol for intestinal absorption. Studies show their effectiveness.
- Eat soya based foods, containing Isoflavones, which help to reduce LDL-C. Choose traditional soya products like tempeh, miso and soy sauce or tamari. Avoid GMO soy. Choose organic, non-GMO or fermented soy. Beware, too much soy foods may not be beneficial if you have thyroid problems.
- Eat more Omega 3 fats – Eating oily fish at least once a week can result in a 15% reduction in risk of cardiovascular disease (CVD) and a 36% reduction in CVD mortality. Try wild-caught salmon, trout, mackerel, sardines and anchovies. The NHS recognises the benefit of oily fish (around two oily–fish based meals a week can be beneficial for lowering triglycerides.
The Portfolio diet was designed by David Jenkins. Michael Moseley, of BBC fame, investigated the claims of the Portfolio diet to reduce cholesterol. The diet is a low-fat, mainly vegan (low dairy & egg) dietary approach combined with cholesterol-lowering plant foods. The results of his investigation were intriguingly mixed. In Dr Mosley’s trial, significant reductions in LDL-C were be obtained by simple dietary changes. The summary is written up nicely here. More details of the Portfolio diet can be found here. Another study supports the portfolio diet for reducing small LDL-C particle number and therefore supporting cardiovascular health.
- Limit alcohol to one unit a day for women and two units for men, advises the current European guidelines for cardiovascular disease.
- Exercise regularly – Studies show consistent, regular exercise can optimise cholesterol and triglyceride levels, lower blood glucose and help maintain a healthy weight.
- 3. Focus on quality sleep – Quality sleep stabilises high blood sugar, which we already know lowers cholesterol. Avoid night-time snacking which raises LDL-C and our risk of obesity.
We know that there is no one single cause for high cholesterol and we know that high LDL-C isn’t the whole answer to atherosclerosis. Otherwise we would be able to explain why many people have raised blood cholesterol but don’t develop heart disease, and vice versa, why many people with coronary artery disease don’t have high blood cholesterol.
Meanwhile, what should we do if we have high cholesterol? I suggest, follow the guidelines – first start with diet and lifestyle modifications, as outlined above. Consider your genetics. Consider your diet, smoking, alcohol, exercise and sleep habits. Remember, cholesterol is only part of the story. Please also consider your blood pressure, glycemic control, weight management and fitness to reduce cardiovascular risk.