Key learning points
- We need the right ratio of “good” and “bad” cholesterol in our diets
- There are a complex mix of factors that contribute towards cholesterol risk
- Nurses should empower patients to take responsibility and control of their own health
Most people probably assume that cholesterol is all bad. But actually, cholesterol plays a vital role in helping the body produce vitamin D, bile for digestion, certain hormones and is even incorporated into cell membranes.
There are different types of cholesterol. Low-density lipoprotein (LDL) is the type that is often associated with negative health effects. Lipoproteins have fat on the inside and proteins on the outside and are comprised of more fat than protein. Excess LDL cholesterol can accumulate and form lipid plaques in the coronary arteries, leading to heart disease. LDL cholesterol usually makes up about 60-70% of total serum cholesterol.
Lipid plaque consists of fat, cholesterol, calcium and other substances. If the plaque constricts the blood vessels, there is an increased risk of diseases such as atherosclerosis, heart attack, stroke, transient ischaemic attacks and peripheral arterial disease.
But high-density lipoprotein (HDL) cholesterol, on the other hand, has the power to soak up excess cholesterol, as it transfers the LDL to the liver to be metabolised. High blood levels of HDLs protect against heart disease. So patients do not need to totally avoid cholesterol. Instead they should know how to get the right ratio in their diet.
If cholesterol builds up it can lead to the formation of plaque in the coronary arteries. Plaque consists of fat, cholesterol, calcium and other substances. If the plaque constricts the blood vessels then the risk of diseases such as atherosclerosis, heart attack, stroke, transient ischaemic attacks and peripheral arterial disease increases.
Who is likely to have a raised cholesterol level?
Patients may inherit a family history of high cholesterol.
Familial hypercholesterolemia is a genetic disorder, caused by a defect on chromosome19. The defect makes the body unable to remove LDL or ‘bad’ cholesterol. This results in a high level of LDL in the blood.
Heart UK1 provides useful information about the role of genetics, explaining that there are many forms of genetic inheritance. More than 100 genes are influential in determining base levels of cholesterol. Various conditions are the result of an interplay between gene types – for example familial hypercholesterolaemia (FH) with an incidence of 1:500; familial combined hyperlipidaemia (FCH), which affects about 1% of the population; and polygenic high cholesterol (PHC), which is much more common and is the result of accumulated effects from a mix of many genes.
Ethnicity and gender also affect a patient’s chances of inheriting a greater risk of developing high levels of cholesterol. People of South Asian origin tend to have more harmful types of LDL cholesterol and less helpful types of HDL cholesterol, compared to people with European ancestry.
South Asian people may also have worse ratios of LDL to HDL cholesterol, which aren’t explained by differences in diet. Additionally, they are more likely to have higher triglyceride levels.
Of course it is difficult to remove the factors of nature, nurture and lifestyle across ethnic groups, but ethnicity and cultural practices should be borne in mind when supporting people in primary care.
Finally, age increases the risk of cholesterol deposition in the arteries. A women’s cholesterol level tends to rise particularly after the menopause, because of the hormonal changes.
Lifestyle factors that influence cholesterol levels
Sleep
Researchers have discovered that both too much and too little sleep have a negative impact on cholesterol levels.2 Sleep duration for both males and females is closely associated with serum lipid and lipoprotein levels.
Other research studies confirm this but also have found that snoring leads to lowering of the good HDL cholesterol.3 This could be due to other factors like obesity and stress, as it is difficult to separate out all possible confounders.
Another study4 suggests that shortened sleep makes people want a more saturated diet and to have less inclination to exercise. Lack of sleep also heightens stress and general anxiety levels, which again links to increased levels of LDL.
Smoking
Smoking damages the blood vessels and increases the risk of plaque buildup. It also reduces the amount of HDL in the blood. This is a problem because HDLs absorb cholesterol and carry it back to the liver, where it is flushed from the body. High levels of HDLs in the blood protect against heart disease.
Experts estimate that a smoker is two to four times more likely to develop heart disease than a person who doesn’t smoke. The risk is even greater if the smoker struggles with high cholesterol.
When patients quit smoking, research suggests a rapid increase in HDL concentrations – in less than three weeks. This emphasises that some, at least, of the adverse effects of smoking appear to be rapidly reversible on quitting, strengthening the argument for encouraging smokers to quit.5
Alcohol
The link between alcohol and cholesterol is less clear. Moderate alcohol consumption appears to raise HDL cholesterol levels by increasing the speeds at which proteins are transported through the body. Exceeding a moderate amount, however, has the opposite effect, as it can raise both cholesterol and triglyceride levels.6,7
Stress
Stress has physiological effects; it causes veins to rupture and serum cholesterol levels to rise.
Stress is related to the production of higher levels of LDL, but research is difficult to conduct because of the variety of confounders. A Scandinavian study8 enrolled more than 40,000 workers in a study of workplace stress and cholesterol and found a direct link with persistent high levels of stress and greater production of LDL. However, diet was not assessed and only one marker was used for measuring stress levels. Other evidence points to the effects of chronic stress on cholesterol levels.9 Animals such as zebras have episodic periods of stress, which their systems can deal with, whereas humans are more likely to suffer prolonged chronic periods of anxiety and stress, which leads to cell damage and cholesterol production.
If there are three risk factors —smoking, high blood cholesterol and a family history of heart disease — the risk for heart disease increases tenfold.
Reliable research
What is reliable research?
Some studies make contradictory claims about the benefits of certain interventions. It can be difficult to find valid research. One controversial study1 states that high levels of LDL in later life actually prolong longevity.
Dr Ravnskov from the University of Lund, Sweden, looked at 19 cohort studies. The researchers that were involved in the 19 studies say that there is no increased cardiovascular risk and that statins will have little effect on lowering LDL. However, when the research is scrutinised it is apparent that there are flaws and assumptions in the study. The researchers of the study have been formally criticised for using crude methods, for example they only searched Pubmed for research studies and two thirds of participants were from only one study, which was the systematic review of 19 cohort studies.10
How can cholesterol be lowered?
What is best practice?
There are levels of management in lowering cholesterol. Initially, advice should be given about the factors that influence cholesterol level (as outlined earlier). Primary care nurses need to give specific advice about diet, exercise, substance use, sleep patterns and stress in a holistic approach.
If necessary, statins will be prescribed when other lifestyle measures have failed to achieve desired levels of cholesterol. The primary action of statins is to lower LDL cholesterol, having only small effects on HDL or triglyceride levels. Treatment with statins usually continues after the target cholesterol is reached, in order to sustain the prevention of atherosclerosis. Statins are generally well tolerated, although some patients complain of adverse reactions such as muscle aches. Patients should have a liver function test prior to statin treatment, to ensure the liver can metabolise waste products adequately.
Health bodies across the UK have developed broadly similar guidelines, including advice about diet, exercise, smoking and medication use. National Institute of Health and Care Excellence (NICE) guidelines from 2008 have been superseded by revised guidelines published in July 2014, with an update in July 2016.11 These are detailed and comprehensive, stressing that a holistic approach should be adopted when supporting patients in primary care. Management should include regular screening and monitoring. Importantly, the guidance views the management of cholesterol as a shared endeavour between patient and health professional and notes that the healthcare practitioner should check that patients understand what is being discussed. Both total and HDL levels should be measured to achieve the best estimate of cardiovascular risk. The guidance also gives specific advice about statin use if initial lifestyle changes do not achieve the desired levels. Guidance recommends atorvastatin (maximum dose 80mg) as first line.
Other relevant guidelines are PH4912 and Guideline CG71.13 Scottish guidance14 is broadly similar to the NICE guidance.
A comparison has been undertaken of the effects of different statins. The Welsh guidance, developed by the Cardiac Network,15 recommends simvastatin as first choice.
Tools to support practice
The Heart Age Tool, developed by the British Heart Foundation (BHF), Public Health England (PHE) and NHS Choices, is a guide and health promotional tool to help people to optimise their heart health.16 It is an online survey that is filled in by patients themselves. It assesses blood pressure measurements and total and LDL cholesterol levels. However, in practice patients are not given their blood pressure recordings and their total and LDL cholesterol levels, this information and nurses need to supply it when patients are screened, for example at well man and women checks. NICE guidance emphasises the importance of encouraging. Primary care nurses could then suggest that patients access the website to check their own heart health. Nurses to empower patients to take responsibility and control of their own health, as emphasisied in current NICE guidance.12
Conclusion
Professor Jeremy Pearson, associate medical director at the British Heart Foundation, says: “As we get older, many more factors determine our overall health, making the impact of high cholesterol levels less easy to detect. The evidence from large clinical trials demonstrates very clearly that lowering LDL cholesterol reduces our risk of premature death overall and from heart attacks and strokes. LDL cholesterol is a major cause of heart disease.”1
Screening and managing cholesterol levels is a public health priority. As cholesterol is needed for healthy functioning and vitamin D manufacture, it is important that cholesterol monitoring is well managed and cholesterol deficiency does not develop. Public health bodies should look at information they give patients and help them to make well informed food choices. Patients should be encouraged at screening checks to use available tools to Tools discussed should be highlighted at screening checks so that patients can track their own health and wellbeing. And much more research is needed to unravel how cholesterol interacts with our genes and other chemicals in the body.
Resources
British Heart Foundation – bhf.org.uk, heart helpline: 0300 330 3300
References
1. Heart UK. Inherited high cholesterol. heartuk.org.uk/inherited-high-cholesterol (accessed 25 August 2016)
2. Kaneita Y et al. Associations of Usual Sleep Duration with serum lipid and lipoprotein levels. Sleep 2008;31(5):645-652.
3. Mosca M, Brooke A. Sleep Duration, snoring habits, and cardiovascular disease risk factors in an ethnically diverse population. Journal of Cardiovascular Nursing2013;27(3):263-269.
4. Gangwisch JE et al. Short sleep duration as a risk factor for hypercholesterolemia: analyses of the National Longitudinal Study of Adolescent Health. Sleep 2010;33(7):956-961.
5. Forey B et al. The effect of quitting smoking on HDL-cholesterol – a review based on within-subject changes. Biomark Research 2013;1:26.
6. De Oliveira, E-Silva ER et al. Alcohol consumption raises HDL cholesterol levels by increasing the transport rate of apolipoproteins A-1 and A-11. National Institute of Health 2000;102(19):2347-52.
7. Vu KN et al. Causal role of Alcohol Consumption in an Improved Lipid profile: The atherosclerosis risk in communities, (ARIC) study. PLoS One 2016;11(2):e0148765. ncbi.nlm.nih.gov/pubmed/26849558 (accessed 25 August 2016)
8. Catalina-Romero C, Calvo E, Sánchez-Chaparro MA et al. The relationship between job stress and dyslipidemia. The Scandinavian Journal of Public Health, 2013.
9. Sapolsky RM. Why Zebras don’t get ulcers: An Updated guide to stress, stress related diseases and coping, 3rd edn 2004.
10. Bathum et al. Association of lipoprotein levels with mortality in subjects aged 50 + without previous diabetes or cardiovascular disease: A population-based register study. Scandinavian Journal of Primary Care 2013;31(3):172-180.
11. National Institute for Health and Care Excellence. Cardiovascular disease: risk assessment and reduction, including lipid modification [CG181], 2014. nice.org.uk/guidance/cg181?unlid=715333182201621351854 (accessed 25 August 2016).
12. National Institute for Health and Care Excellence. Behaviour change: individual approaches [PH49], 2014. nice.org.uk/guidance/ph49 (accessed 25 August 2016).
13. National Institute for Health and Care Excellence. Familial hypercholesterolaemia: identification and management [CG71], 2016. nice.org.uk/guidance/cg71?unlid=5392446542016424154225 (accessed 25 August 2016).
14. Scottish Intercollegiate Guidelines Network. Risk estimation and the prevention of cardiovascular disease, 2007. sign.ac.uk/guidelines/fulltext/97/ (accessed 25 August 2016).
15. North Wales Cardiac Network. Statin Guideline Summary, 2008. wales.nhs.uk/sitesplus/documents/861/Statin%28full%29guideline_NWCN.May08.pdf (accessed 25 August 2016).
16. NHS Choices. Check your heart age. nhs.uk/tools/pages/heartage.aspx (accessed 25 August 2016).
