This research was planned to prevent secondary hyperlipidemia, which may occur due to isotretinoin used in the treatment of severe acne, with diet. There will be three different groups and followed for 12 weeks. Groups will be; Mediterranean Diet, Low Cholesterol Diet (<200 mg/day) and the Control Group.

Isotretinoin has been officially used to treat severe cystic acne since the 1980s. The drug is a retinoic acid derivative and works by reducing the size of the sebaceous glands and sebum production. Thanks to this effect, the lipid profile on the skin surface changes and the bacterial skin flora decreases.

The drug also has a side effect of increasing blood lipids, causing secondary hyperlipidemia. This research examines the effects of low cholesterol diet and Mediterranean diet on blood lipids, which are implemented to prevent the increase of blood lipids.

The research was designed as an experimental intervention research and will conducted at Nevruz Erez State Hospital Skin and Venereology Polyclinics between November 2023 and April 2024, with volunteers who meet the research criteria.

H0: Secondary hyperlipidemia due to isotretinoin use cannot be prevented by diet.

H1: Secondary hyperlipidemia due to isotretinoin use can be prevented by diet. People who volunteer to participate in the research will be informed in detail about the research with the Informed Consent Form and then will be grouped by the list method. At the beginning of the research, the Personal Information Form, the Mediterranean Diet Adherence Scale and the Food Consumption Frequency form prepared by the researcher will be applied to all patients who volunteer to participate in the research. The results of Biochemistry and Hemogram tests performed by the doctor will be recorded.

During the research, the blood findings (Total Cholesterol, HDL-Cholesterol, LDL-Cholesterol, Triglyceride, ALT, AST and Hemogram) of the patients in each group will be checked monthly by the Skin and Venereology Polyclinic Physician who follows their treatment, and the patients' isotretinoin doses will be completely adjusted by the doctor. No intervention other than diet will be made by the researcher.

Sample size of the study (n); Effect size (d) = 0.94, significance level (α) = 0.05, power of the test (1-β) = 80% were entered into the Gpower program and calculated as 32(n) for two groups. This research will be conducted with three different groups, in this case, it is planned to complete the research on a total of at least 48 patients, namely the Mediterranean Diet Group (n1) = 16, the Low Cholesterol Diet Group (n2) = 16 and the Control Group (n3) = 16.

Considering that the research period is 12 weeks, 25% more people will be recruited for each group in case the patients leave the study or are excluded from the research. In this situation; Mediterranean Diet Group (n1) = 20 people, Low Cholesterol Diet Group (n2) = 20 people, Control Group (n3) = 20 people, Total Sample Size (n) = 60 people. The total research duration for all groups participating in the research is planned to be 12 weeks.

Inclusion Criteria:

Patients must be treated for acne and must be new to oral isotretinoin treatment, Aged must be 18 - 65 years old, Body Mass Index must be between 18-24.99 kg/m2, LDL Cholesterol must be <130 mg/dL, Triglyceride must be <150 mg/dL.

Exclusion Criteria:

Cardiovascular diseases, Kidney diseases, Eating disorders, Hyperlipidemia, Insulin resistance, Metabolic diseases, Diabetes, And who used the drugs for the treatment of these diseases, BMI <18 kg/m2, >25 kg/m2 Aged <18 and >65 will not be included in the study.