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LDL-Cholesterol

LDL CHOLESTEROL (KOL-LDL)

Low-density lipoprotein (LDL) cholesterol is a lipoprotein that carries cholesterol (70 % of all cholesterol) in the blood. LDL cholesterol consists mostly of cholesterol and a small amount of protein. It is the primary cholesterol-carrying lipoprotein in the blood. LDL cholesterol carries LDL particles, meaning LDL cholesterol acts as a transportation for them. Cells receive LDL particles and utilize the lipids needed. LDL cholesterol moves relatively slowly in the blood and, therefore prone to oxidation (ox-LDL). Oxidized LDL that attaches to the endothelium significantly impairs blood vessel function and circulation.


High LDL and total cholesterol levels, together with inflammation or endothelial damage, may lead to the build-up of atherosclerotic plaque and the resulting constriction of blood vessels, cardiovascular disease, and later cardiac arrest and stroke (see above). This is why LDL cholesterol is often called “bad” cholesterol. Epidemiological studies have found that LDL cholesterol is linked to increased arterial plaque and higher overall mortality in healthy individuals. However, a cause-and-effect relationship should not be interpreted from these findings. It appears that prolonged high LDL cholesterol levels have a cumulatively detrimental effect, increasing the hardening of arteries. Individuals with a high risk of cardiovascular disease benefit from lowering their LDL cholesterol levels (particularly individuals with familial hypercholesterolemia).


NB! Low LDL cholesterol levels (including total cholesterol) do not guarantee that atherosclerosis will not develop. This has been found in several studies tracking the relationship between cardiac mortality and LDL cholesterol levels. In some cases, low LDL cholesterol levels have even been linked to higher cardiac mortality. For this reason, the primary concern should also be the good management of silent inflammation and insulin sensitivity to inhibit the development of cardiovascular diseases.


Excessively low LDL cholesterol levels may lead to various health issues such as disruptions in the production of steroid hormones and bile acids, disruptions in adrenal gland function, depression, type 2 diabetes (complication caused by statins), anxiety, neurological problems, self-destructiveness, even stroke. Extremely low LDL cholesterol levels are also linked to an increased risk of infectious diseases and cancer. Extremely low LDL cholesterol levels are usually caused by cholesterol medication, although they may also be associated with rare genetic lipoprotein metabolism disorders (mutations of the ANGPTL3 gene).


Factors that increase LDL cholesterol include smoking, excessive alcohol use, poor diet (low on vegetables and good fats), obesity, and a sedentary lifestyle. A high-fat diet (such as a ketogenic or low-carb diet) may also temporarily increase LDL cholesterol levels (see above), although after an adaptation period of a few months, they usually return to a level that is lower than before.291 Thus the results should be assessed based on the individual's diet.


NB! Rather than LDL cholesterol, a better indicator of cardiovascular disease risk is the LDL particle count (see above). Significant discrepancy may occur between LDL cholesterol and LDL particle counts, i.e. LDL cholesterol may be high while the LDL particle count is proportionally much lower. On the other hand, the opposite may also apply (lower LDL cholesterol, higher LDL particle count).


The LDL particle count can be studied with a specific method, although this is currently quite expensive (not included in the HealthDx kits). In the future, HealthDx strives to offer a comprehensive lipid test kit conducted using the NMR method, to provide deeper information on lipids.


A low-carbohydrate diet has been commonly found to be a significantly more effective method for weight loss and lowering the risk of cardiovascular disease than a low-fat diet, despite its slight increase in LDL cholesterol levels caused by it. A low-carb diet usually results in a decreased LDL particle count while increasing HDL cholesterol levels and the size of LDL cholesterol – a change with health benefits (cf. small LDL cholesterol size). The amount of harmful very low-density lipoprotein (VLDL) cholesterol has also been reduced by consuming a low-carb/ketogenic diet.


However, it should be noted that the low-carb/ketogenic (high-fat) diet is not suitable for some individuals, most likely due to genetic reasons (such as the ApoE 4/4 gene variant, familial hypercholesterolemia, or ApoA2 CC gene variant2). In these cases, the anti-inflammatory diet is also beneficial, although, in terms of carbohydrate intake, it should resemble the Mediterranean diet where the role of cold-pressed olive oil is highly significant as a fat source (at the same time reducing the intake of saturated fat) while not dramatically restricting the consumption of carbohydrates.


In 2004, the Nordic Reference Interval Project (NORIP) determined the reference range for LDL cholesterol for healthy adults:
The reference range for adults according to the NORIP study:

  • Aged 18–29: 1.2–4.3 mmol/L
  • Aged 30–49: 1.4–4.7 mmol/L
  • Aged 50+: 2.0–5.3 mmol/L

The ratio of total cholesterol to HDL cholesterol is a good indicator of the risk of cardiovascular mortality. The Chol/HDL ratio reflects how long LDL particles remain in the blood. The longer they circulate in the blood, the more prone they are to oxidative stress caused by free radicals, and thus oxidation (so-called oxidized LDL-C). Oxidized LDL cholesterol is particularly harmful to blood vessels.