A majority of high-risk patients does not achieve their cholesterol target levels and most of these patients do not receive more effective combination therapy, which goes beyond statin monotherapy. Large interindividual differences in treatment outcomes have been observed for patients receiving statins. Statins block cholesterol synthesis and increase cellular low-density lipoprotein (LDL) uptake. Importantly, LDL uptake is highly divergent in individuals.The aim of this trial is to investigate how atorvastatin influences leukocyte readouts of LDL uptake and lipid storage in humans. The trial is a single-arm, open-label, interventional trial. A total of 15 healthy volunteers will receive 40 mg atorvastatin once a day for 4 weeks. The participants will provide blood samples before starting the atorvastatin intervention, each week when taking atorvastatin, and one week after the end of the intervention for the measurement of leukocyte readouts of LDL uptake and lipid storage.

Inclusion Criteria:

1. a signed written informed consent
2. age 18-40 years
3. healthy, and
4. Accepted results from laboratory tests (blood haemoglobin, basic blood count and blood platelets, alanine aminotransferase, alkaline phosphatase, glutamyl transferase, creatinine, plasma potassium and sodium). Negative pregnancy test result (serum human chorionic gonadotropin) for women.
5. Fully vaccinated against COVID-19.

Exclusion Criteria:

1. significant disease
2. smoking
3. SLCO1B1 poor function genotype
4. oral contraception or other continuous medication
5. pregnancy, planning of pregnancy or breastfeeding
6. participating in a clinical trial less than 3 months ago
7. donating blood less than 3 months ago
8. marked obesity
9. anticipated difficulties in drawing blood samples
10. weight less than 45 kg
11. BMI less than 18.5 kg/m2 or
12. inadequate Finnish language skills