The physiological processes of the body present daily oscillations called circadian rhythm. The circadian rhythm is essential for maintaining the vital functions of organisms, intervening directly and indirectly in a multitude of key processes, such as hormone secretion, cycles of activity and rest throughout the day, body temperature, the metabolism or absorption, processing and detoxification of nutrients. There are factors such as certain work schedules, prolonged exposure to screens, certain eating patterns or social jetlag, which have a negative impact on the circadian rhythm, causing its disruption and favoring the appearance of health alterations. Thus, there is evidence that associates night shift work with a higher incidence of risk factors for developing metabolic syndrome and cardiovascular diseases, including obesity, elevated blood levels of glucose, triglycerides, and low-density lipoprotein cholesterol (LDL-C), as well as lower levels of high-density lipoprotein cholesterol (HDL-C). In addition, disorders in the sleep cycle are associated with the development of hypertension and type 2 diabetes.

Several previous studies show that a grape seed proanthocyanidin extract (GSPE) has beneficial effects on different parameters by restoring the circadian rhythm.

The main objective of the study is to evaluate the effect of daily GSPE intake, in combined with dietary recommendations, on LDL-C levels in individuals with rotating night shift work.

The secondary objectives are to evaluate the effects of GSPE on: anthropometric parameters,blood pressure, heart rate and endothelial function, markers of lipid and carbohydrate metabolism and insulin resistance, atherogenic indices, circulating levels of sex hormones and those related to hunger, satiety and stress; markers of systemic inflammation; circadian rhythm markers and sleep quality; level of physical activity, energy consumption, and changes in gene expression of key metabolic enzymes.

A randomized, crossover, placebo-controlled, triple-blind nutritional intervention study will be conducted. The study will be carried out in a population of 22 volunteers. Men and women aged 18 years or older, who are working a rotating night shift for at least 1 year and with blood levels of LDL-C between 116 and 190 mg/dL may participate.

Each volunteer will make 5 visits to the facilities of the EURECAT Nutrition and Health Technological Unit, in accordance with the study design:

• A pre-selection visit (to check inclusion/exclusion criteria), and if the inclusion criteria are met.
• Two study visits during consumption of the first product (GSPE or placebo), which will take place on the first day of study (visit 1) and after 6 weeks of treatment (visit 2).
• Two study visits during consumption of the second product (GSPE or placebo), which will take place after a three-week washout period (visit 3), and after 6 weeks of treatment (visit 4).

The main variable of the CIRCAFENOL study is circulating LDL-C levels.

Inclusion Criteria:

• Men and women aged 18 years or older.

• Follow a rotating night shift work schedule* for at least one year before the start of the study.

  * shift workers with at least 5 night shifts per month alternating with day and/or afternoon shifts, with a seniority equal to or greater than one year.

• Have no intention of changing the work shift during the course of the study.

• Circulating LDL-C levels between 116 -190 mg/dL*, without pharmacological treatment with antihypertensives and/or lipid-lowering agents.

  *Values of 116 to 190 mg/dl indicate moderate alteration in the lipid profile and a greater risk of suffering from cardiovascular diseases, according to the European Society of Cardiology, and the European Society of Atherosclerosis.

• Have signed the informed consent before starting the study.

• Know how to read, write and speak in Catalan or Spanish

Exclusion Criteria:

• BMI values > 30 kg/m2

• Take supplements, multivitamin supplements (Vit.D, Vit. E and Vit.C), mineral supplements (Zinc, Selenium), essential fatty acids (omega-3), polyphenols, natural plant extracts, or phytotherapeutic products that interfere with the treatment under study.

• Consumption of alcoholic beverages:

  • Men: consume 4 or more Standard Beverage Units daily or 28 Standard Beverage Units weekly.
  • Women: Consume 2 or more Standard Beverage Units daily or 17 Standard Beverage Units weekly.

• Be an active smoker.

• Having lost more than 3 kg of weight in the last 3 months.

• Present food intolerances and/or allergies related to the study products, such as hypersensitivity to cellulose or proanthocyanidins.

• Present any chronic or autoimmune disease in clinical manifestation that may affect the results of the study such as diabetes (type I or II), cardiovascular disease, chronic kidney disease, hyper or hypothyroidism, chronic gastrointestinal diseases or cancer.

• Present familial hypercholesterolemia.

• Present hypertension (Systolic ≥140 mmHg; Diastolic ≥90 mmHg)

• Present any previous cardiovascular disease defined as myocardial infarction, angina pectoris, stroke or peripheral arterial disease.

• Individuals with treatment in the last 3 months before the start of the study with lipid-lowering, antidiabetic and/or antihypertensive drugs, or other drugs that may interfere with the results of the study.

• Taking supplements with polyphenol components or those aimed at lipid or blood pressure control in the last 3 months before the start of the study or during participation in the study.

• Follow a diet to lose weight, or very restrictive types of eating, such as intermittent fasting, ketogenic diet, etc.

• Being pregnant or intending to become pregnant.

• Being breastfeeding.

• Be participating or have participated in a clinical trial with medications or nutritional intervention study in the last 30 days before inclusion in the study.

• Suffering from eating disorders or psychiatric disorders.

• Being unable to follow study guidelines.