HDLmmol/L
Reverse-cholesterol transport capacity
Also known as: HDL Cholesterol
Typical optimal range
1–3 mmol/L
Female
A commonly cited optimal range for HDL cholesterol is 1.0–3.0 mmol/L, though exact reference ranges vary between laboratories and should always be interpreted alongside the report from your own lab. These figures are indicative — the range printed on your own lab report is the definitive one for your results.
Lipid assessment and cardiovascular risk management in the UK follow NICE guideline NG238 (Cardiovascular disease: risk assessment and reduction, including lipid modification).
What is HDL?
HDL (high-density lipoprotein) is a particle that transports cholesterol from artery walls and peripheral tissues back to the liver for processing and excretion — a process known as reverse cholesterol transport. Unlike LDL, higher circulating levels of HDL cholesterol are generally associated with a lower risk of cardiovascular disease. Measuring HDL in a routine blood test gives clinicians a useful piece of the overall cardiovascular risk picture, and it is typically reported alongside total cholesterol, LDL, and triglycerides as part of a full lipid profile.
What a high HDL means
An HDL result above the typical range is not usually a cause for concern and in most cases simply reflects a favourable cardiovascular profile. That said, very high HDL levels (broadly above 2.5 mmol/L) have not been shown in clinical trials to confer additional protective benefit, and in rare cases extremely elevated HDL may warrant a conversation with your GP.
- Genetic variation. Some people naturally produce higher HDL due to inherited differences in lipid metabolism; this is usually benign and found incidentally on routine testing.
- Regular aerobic exercise. Sustained aerobic activity is one of the most reliably documented ways to raise HDL, so a high result may simply reflect a physically active lifestyle.
- Certain medications. Some medicines, including certain fibrates and niacin-based treatments, can elevate HDL as part of their mechanism; always review your result in the context of any current medications.
Isolated very high HDL is rarely acted upon clinically without other abnormal lipid findings, but if your result sits well outside the reference range on your report, it is worth flagging to your GP.
What a low HDL means
A low HDL cholesterol result is the clinically important direction for this marker — lower levels are independently associated with an increased risk of cardiovascular disease, including coronary heart disease. A single low reading is not a diagnosis, but it is a useful prompt to look at the broader picture of your lifestyle, metabolic health, and overall cardiovascular risk.
- Physical inactivity. A sedentary lifestyle is one of the most common contributors to low HDL; even modest increases in regular movement can have a measurable effect over time.
- Smoking. Smoking consistently lowers HDL cholesterol, and stopping smoking is associated with meaningful improvements in HDL levels as well as broader cardiovascular benefit.
- Metabolic syndrome & insulin resistance. Low HDL is a recognised feature of metabolic syndrome — a cluster that also includes raised triglycerides, central adiposity, raised blood pressure, and impaired blood glucose regulation — and may prompt your GP to check these markers too.
A diet high in refined carbohydrates and ultra-processed foods can also suppress HDL; alcohol has a complex relationship with HDL — moderate intake has been associated with slightly higher levels in observational studies, but current NHS guidance does not recommend drinking alcohol for any health benefit.
Should I be worried?
A single HDL result — whether low or reassuringly high — is best understood as one piece of information rather than a verdict on your heart health. Cardiovascular risk is calculated from several factors together, including total cholesterol, LDL, triglycerides, blood pressure, smoking status, age, and family history, so your GP will usually look at the full picture rather than any one number in isolation. If your HDL is consistently low on repeat testing, or sits alongside other abnormal lipid markers, your GP may use a formal risk calculator (such as QRISK3) to assess your overall cardiovascular risk and discuss whether any further investigation or intervention is appropriate. There is no need to panic over a single result, but it is a good reason to book a routine review if you have not had one recently.
What actually helps
If your HDL is lower than optimal, several well-evidenced lifestyle changes can support meaningful improvement over time.
- Aerobic exercise. Regular moderate-to-vigorous aerobic activity — such as brisk walking, cycling, or swimming — is one of the most effective evidence-based ways to raise HDL cholesterol; current NHS guidance recommends at least 150 minutes of moderate activity per week.
- Resistance training. Adding resistance or strength training alongside aerobic exercise provides additional cardiovascular benefit and has been shown to contribute modestly to HDL improvement.
- Stop smoking. Quitting smoking reliably improves HDL levels and dramatically reduces overall cardiovascular risk; free NHS Stop Smoking services can provide structured support.
- Reduce refined carbohydrates and ultra-processed foods. Swapping refined carbohydrates and sugary foods for whole grains, vegetables, and legumes is associated with improved HDL and triglyceride levels over time.
Certain foods have good supporting evidence for a positive effect on HDL or the wider lipid profile.
Oily fish (salmon, mackerel, sardines)
Rich in long-chain omega-3 fatty acids, which have well-established evidence for improving triglyceride levels and supporting overall cardiovascular health; the NHS recommends at least one portion of oily fish per week.
Olive oil and other sources of monounsaturated fat
Replacing saturated fat with monounsaturated fat — as in a Mediterranean-style diet — is associated with modest improvements in HDL and a more favourable overall lipid profile.
Nuts (especially walnuts and almonds)
Regular nut consumption has been linked in multiple studies to modest improvements in HDL and reductions in LDL, likely due to their content of unsaturated fats, fibre, and plant sterols.
Legumes (beans, lentils, chickpeas)
High in soluble fibre, legumes support healthy lipid levels and are a cornerstone of dietary patterns consistently associated with lower cardiovascular risk.
Whole grains (oats, barley)
Soluble fibre from oats and barley in particular has strong evidence for improving overall cholesterol balance, and these foods support steady blood sugar — relevant given the link between insulin resistance and low HDL.
Avocado
A good source of monounsaturated fat and plant sterols; some controlled trials show modest HDL-raising effects when avocado replaces sources of saturated fat in the diet.
Track your own HDL
Upload a lab PDF and Better Days trends HDL over time, flags it when it drifts, and suggests foods that help.
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Sources & further reading
These are reputable UK health resources for further reading. This page is written to be consistent with their guidance but is not a substitute for them.
For information only — not medical advice, and not individually reviewed by a clinician. Reference ranges vary by lab and individual. Discuss any results with a qualified clinician before making changes.