Heart disease risk: what your blood tests reveal before symptoms appear

Atherosclerosis: how plaque forms in arteries

The underlying process behind most heart attacks and strokes is atherosclerosis: the progressive accumulation of plaque in arterial walls over time. It begins when atherogenic lipoprotein particles (primarily LDL and its variants) enter the inner layer of the arterial wall and become oxidised. The immune system responds to this as if to a threat, sending macrophages (white blood cells) that engulf the oxidised LDL. These become "foam cells" that form the earliest fatty streaks of plaque. Inflammation accelerates the process, leading to progressive plaque growth, arterial narrowing, and eventually the rupture of unstable plaques that triggers blood clots. Understanding this process helps explain why both the number and character of atherogenic particles (not just total cholesterol) and the level of systemic inflammation matter for accurate risk assessment.

LDL particle number and ApoB: looking beyond the cholesterol amount

Standard cholesterol tests measure the amount of cholesterol carried by LDL particles, not how many LDL particles are present. This distinction matters because each LDL particle carries exactly one molecule of apolipoprotein B (ApoB), so measuring ApoB gives a direct count of atherogenic particles in the blood. Research consistently finds that ApoB is a more accurate predictor of cardiovascular events than LDL cholesterol, particularly in people with metabolic syndrome, type 2 diabetes, or obesity, where a pattern of many small cholesterol-poor LDL particles is common. These individuals can have normal or only modestly elevated LDL cholesterol while having high ApoB, meaning their true particle burden and cardiovascular risk is greater than the standard result suggests.

Lipoprotein(a): the inherited cardiovascular risk factor most people have never tested

Lipoprotein(a), usually written Lp(a), is a variant of LDL with an extra protein attached that makes it particularly sticky and likely to promote clot formation. Elevated Lp(a) is almost entirely genetically determined and affects roughly 1 in 5 people globally. Unlike most cardiovascular risk factors, Lp(a) is not substantially reduced by lifestyle changes, statins, or standard cholesterol treatments. People with elevated Lp(a) carry a significantly higher risk of heart attacks and strokes, even when their LDL cholesterol is well controlled. Most people with elevated Lp(a) have never been told they have it, because it is not included in standard lipid panels. New therapeutic agents specifically targeting Lp(a) are in late-stage clinical trials, making early detection increasingly relevant for future treatment options.

Homocysteine and the methylation connection

Homocysteine is an amino acid produced as a byproduct of the methionine metabolism pathway. When homocysteine is not adequately cleared, which can result from low B12, low folate, low B6, or genetic variants affecting the methylation pathway (particularly the MTHFR gene), it accumulates and damages arterial walls. A 2022 systematic review and meta-analysis found that every 5 umol/L increase in plasma homocysteine is associated with approximately a 22% higher risk of coronary heart disease. Elevated homocysteine is an independent cardiovascular risk factor that can be present without any abnormality in LDL or total cholesterol, and it is directly addressable through B vitamin supplementation and dietary changes. Importantly, MTHFR gene variants (which affect a significant proportion of the population) impair the body's ability to convert folate into its active form, raising homocysteine through a genetic mechanism. DNA testing that identifies these variants allows for targeted intervention with the active (methylated) forms of B vitamins.

High-sensitivity CRP and vascular inflammation

High-sensitivity CRP (hs-CRP) measures low-level systemic inflammation that standard CRP tests do not detect. Chronic vascular inflammation drives the atherosclerotic process directly: it promotes the oxidation of LDL particles, accelerates foam cell formation, and destabilises existing plaques. The Physicians' Health Study found that elevated hs-CRP conferred an approximately threefold increased risk of heart attack in men who were otherwise considered low risk based on standard lipid panels. The Women's Health Study found hs-CRP to be the strongest predictor of cardiovascular events in women. Chronic conditions that raise CRP, including insulin resistance, obesity, sleep disorders, periodontal disease, and smoking, also increase cardiovascular risk through this inflammatory mechanism.

Metabolic health: the cardiovascular risk multiplier

Insulin resistance, elevated blood sugar, and the metabolic syndrome pattern (high triglycerides, low HDL, elevated blood pressure, central obesity, elevated blood sugar) do not just increase cardiovascular risk independently, they interact with the lipid and inflammatory mechanisms to amplify risk substantially. HbA1c reflects three months of blood sugar control and gives a measure of how well the body is managing glucose over time. Elevated HbA1c, even at levels below the clinical threshold for diabetes, is associated with progressive cardiovascular risk through several mechanisms: glycation of arterial wall proteins, worsening of the small dense LDL pattern, and increased inflammatory markers.

A comprehensive cardiovascular risk assessment through blood testing goes beyond the standard cholesterol check to include the markers that predict risk independently and that the standard panel misses.

LDL cholesterol, HDL cholesterol, total cholesterol, and triglycerides form the standard lipid panel. The total cholesterol-to-HDL ratio is the most useful single number from this panel for risk assessment.

ApoB counts the total number of atherogenic particles in the blood, giving a more accurate risk assessment than LDL cholesterol alone for people with metabolic syndrome, diabetes, or obesity. Growing evidence supports ApoB as the preferred lipid treatment target, though it is not yet included in standard NHS panels.

Lp(a) identifies whether you carry an inherited risk factor for cardiovascular disease that exists independent of lifestyle. European and US cardiovascular society guidelines now recommend that everyone have Lp(a) measured at least once in their lifetime.

Homocysteine assesses methylation pathway function and provides an independent cardiovascular risk signal that is addressable through targeted B vitamin supplementation or dietary change.

High-sensitivity CRP (hs-CRP) measures vascular inflammation at a level that standard CRP tests do not detect. Levels below 1.0 mg/L are low risk, 1.0-3.0 mg/L intermediate, and above 3.0 mg/L high risk for cardiovascular events.

HbA1c reflects average blood sugar control over three months, addressing the metabolic dimension of cardiovascular risk.

Dietary quality and the anti-atherosclerotic diet

The dietary patterns most consistently associated with reduced cardiovascular risk are the Mediterranean and DASH diets, both of which prioritise vegetables, legumes, whole grains, nuts, fish, and olive oil while limiting red meat, saturated fat, ultra-processed foods, and added sugars. The cardiovascular benefits appear to come from multiple mechanisms simultaneously: improved lipid profile, reduced systemic inflammation (lower CRP), better blood sugar control (lower HbA1c), and reduced homocysteine through adequate B vitamin intake. Tracking these markers together shows whether your dietary approach is producing measurable biological change, not just alignment with dietary principles.

Exercise and arterial health

Regular aerobic exercise has direct effects on arterial health beyond its impact on lipid numbers. It promotes endothelial function (the health and responsiveness of the inner arterial wall), reduces resting heart rate, lowers blood pressure, raises HDL, reduces triglycerides, and decreases systemic inflammation. The dose-response relationship shows benefits from as little as 150 minutes of moderate-intensity exercise per week, with additional benefits from higher volumes and the inclusion of vigorous-intensity activity. Resistance training adds to cardiovascular benefit through its metabolic effects on insulin sensitivity and body composition.

Managing homocysteine through B vitamin optimisation

When homocysteine is elevated, the most direct intervention is optimising the B vitamins involved in its clearance: folate (ideally in the methylated form, 5-MTHF, for people with MTHFR variants), B12 (ideally methylcobalamin), and B6. Dietary sources include dark leafy greens, legumes, liver, eggs, and fish. Supplementation with methylated B vitamins is appropriate when dietary intake is insufficient or when MTHFR variants impair conversion of standard folic acid. Retesting homocysteine after 3-6 months of B vitamin optimisation gives a direct measure of whether levels are moving toward the optimal range (below 10-12 umol/L).

Reducing inflammatory load

Because CRP reflects the same vascular inflammation that drives atherosclerosis, interventions that reduce CRP also reduce one of the core mechanisms of cardiovascular risk progression. These include: resolving insulin resistance and metabolic syndrome, reducing visceral fat, stopping smoking (one of the strongest inflammatory drivers), treating sleep disorders, improving dietary quality (omega-3 fatty acids, polyphenols, and fibre all reduce inflammatory markers), and managing chronic psychological stress. Tracking hs-CRP alongside lipid markers shows whether your overall approach is reducing vascular inflammation over time.