Q: What is high cholesterol & why is it a threat to pilots?
Cholesterol is a type of fat (lipid) that is obtained from our diet (about 25%) & manufactured in the liver (about 75%), then transported in our blood by “courier” proteins (lipoproteins). While cholesterol is essential to maintain healthy cells & produce hormones (like testosterone & Vitamin D), high cholesterol increases our risk of coronary heart disease, heart attack, stroke & eye disease. This is because over time (with other risk factors like hypertension & diabetes) fatty-deposits build up in the small arteries (arterioles), reducing the flow of blood to the heart, brain or retina (in the eyes).
High cholesterol (hyperlipidaemia or hypercholesterolaemia) is defined as total cholesterol greater than 5.5 millimoles per litre (mmol/L), while disordered cholesterol (dyslipidaemia) is defined as an abnormal ratio of the “bad” to “good” cholesterol greater than 5.
Q: Why is high cholesterol relevant to pilots & aviation safety?
High cholesterol levels increase our risk of coronary artery disease (atherosclerosis), heart attack, stroke and eye disease all of which can temporarily or permanently ground us. CASA also requires commercial pilots with a class 1 medical to have blood fat tests (lipid studies) & cardiovascular disease (CVD) risk assessments throughout their career. If the CVD risk assessment score is greater than 14, CASA requires further tests (such as: exercise stress ECG or CT coronary angiogram) to exclude coronary artery disease.
Furthermore, inherent aspects of a career in aviation actually increase the risk of high cholesterol levels such as: shift work, trans-meridian flights, disruption of the sleep-wake cycle, poor diet & sedentary occupation. For all these reasons it is essential that pilots be proactive to monitor & maintain normal cholesterol levels.
By way of an aviation analogy, a pilot with high cholesterol levels is a bit like an aircraft that has been filled with a highly viscous type of engine oil that occludes the oil circulation system, resulting in reduced oil flow through the engine and a greater risk of damage or sudden failure.
Q: What are the symptoms & how is high cholesterol diagnosed?
Much like a microscopic crack in an airframe or fan-blade, there are usually no symptoms or signs of high cholesterol until coronary artery disease (atherosclerosis) is quite advanced. This is because fats silently build-up within the walls of our arteries & only tend to cause symptoms once the arteries have a 70% blockage (see figure above). Symptoms of coronary artery disease include: chest, throat/jaw or arm pain, shortness of breath, increased heart beat or palpitations, fatigue & decreased exercise tolerance.
High cholesterol (hypercholesterolaemia) is diagnosed on blood lipid studies when cholesterol is above 5.5 (mmol/L).
Q: What causes high cholesterol?
High cholesterol is mostly caused by genetic, dietary & lifestyle factors, such as: a diet high in sugars, animal fats & processed foods, overweight or obesity, sedentary lifestyle & shift-work (part of an aviation career), smoking, male gender & age. In some people family history & genetics plays a significant role in developing high cholesterol levels, for example: familial hypercholesterolaemia.
Q: What types of blood cholesterol & fats (lipids) are there?
Blood fat tests (lipid studies) measure our Total Cholesterol and other lipids circulating in our blood, which is made up of:
HDL “Good Cholesterol” -High Density Lipoproteins pick up excess cholesterol and carry it to the liver for removal - HDL lowers the risk of heart disease, heart attack & stroke.
LDL “Bad Cholesterol” - Low Density Lipoproteins carry cholesterol around the body but tend to build up in the walls of our arteries, narrowing them and increasing the risk of heart disease, heart attack & stroke.
Triglycerides - provide an energy source and are the most common type of fat in our body - but high levels increase the risk of heart disease & stroke
Q: Can I fly with high cholesterol & how does it affect my medical certificate?
In the short to medium term, pilots with elevated or high cholesterol (in the absence of other risk factors for heart disease) will be able to continue flying. However, over the course of a flying career it is likely that elevated cholesterol levels (together with other risk factors such as hypertension, diabetes or abnormal fasting glucose) will impact a pilot’s medical certificate at some point. Therefore, it is critical that pilots work with their GP or cardiologist to get their cholesterol and blood lipid levels within the target ranges.
Q: What are the target ranges?
High cholesterol levels are treated by modifying a pilot’s lifestyle in conjunction with taking cholesterol lowering medications to achieve cholesterol within the healthy target ranges:
Depending on a pilot’s specific risk factors (hypertension, diabetes, obesity, heart disease or smoking), the target ranges may be much lower & tailored by the GP or cardiologist.
Q: How is high cholesterol treated in pilots?
Treatment of high cholesterol is acheived with:
Lifestyle modifications - smoking cessation, weight-loss, regular exercise & diet (low in sugar, processed foods & animal fats)
Cholesterol lowering medications - statins, bile-acid resins, fish oils, fibrates, cholesterol absorption blockers or niacin (Vitamin B3)
Q: Counter measures - What can pilots do about high cholesterol?
As Pilots we must focus on monitoring & maintaining our health (not simply passing our annual medical) just as we inspect the maintenance release of aircraft & monitor the temperatures & pressures in flight. The easiest way is by forming good habits early (just like learning to brush our teeth as kids…it’s easy now because it’s a habit).
Start Now - check your cardiovascular disease risk profile here
Here are 5 good health habits for pilots to lower their cholesterol levels:
Dietary habit - low salt, low sugar & low saturated fat diet with plenty of low GI whole grain carbohydrates, fruits, leafy green vegetables, healthy fats like avocado & lean meat like fish & chicken (drink alcohol & coffee in modest quantities or skip it all together) - AVOID fried foods, animal fats, canola oil & coconut cream, sugary drinks & sugary foods.
Exercise habit - regular aerobic & resistance exercise ideally 20 to 30 mins every day but at least 30 to 45 mins x 3 per week.
Sleep habit - go to bed at a consistent time & get at least 7 to 9 hours of sleep daily.
Weight habit - maintain a healthy weight - if you start having to let your belt out a notch - then work with your GP or a dietician to lose it.
GP habit - find a good GP you like & trust & check in with them once or twice a year to review your cholesterol levels & general health.
If you have high cholesterol TAKE CORRECTIVE ACTION work with your GP or cardiologist to get it down to the lowest level possible.
Q: Got more questions?
Contact us: info@aerokare.com.au
References & links to more information:
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