In this study the effects of different dosages and preparations of krill oil in comparison to placebo on symptoms of premenstrual syndrome in healthy, female adults will be assessed.

The study is a randomized, placebo-controlled, double-blind, parallel group trial, in which the effect of krill oil is investigated in healthy female volunteers showing premenstrual symptoms. The study period covers a time period over 6 menstrual cycles of women under which the first two cycles are recorded to assess baseline conditions followed by a 4-cycle supplementation phase. Volunteers are randomly allocated to the 5 study groups including placebo and 4 different dosages and formulations of krill oil. Over the whole study period, volunteers report daily their symptoms in the validated questionnaire DRSP. Mood state and quality of life are assessed at baseline and after two and 4 cycles of supplementation.

Inclusion Criteria:

• Subject is able and willing to sign the Informed Consent Form prior to screening evaluations
• Age: 20 - 50 years
• Sex: female
• Premenopausal
• Regular menstrual bleeding
• History of and presence of PMS symptoms of at least 6 months
• Subject is in good physical and mental health as established by medical history, physical examination, electrocardiogram, vital signs, results of biochemistry, haematology

Exclusion Criteria:

• BMI: < 19 kg/m2, ≥ 30 kg/m2
• Heavy smoker >15 cigarettes / day
• Known pregnancy, breast feeding or intention to become pregnant during the course of the study
• No use of acceptable contraceptive method during the study
• Menstrual cycle lasting less than 24 / longer than 35 days
• Hormone treatment because of premenstrual symptoms
• Diagnosed premenstrual dysphoric disorder (PMDD), a severe form of PMS
• Regular consumption of omega-3 fatty acids (e.g. nutritional supplements) within previous 3 months or during the study course
• Fish consumption of more than 1 serving of fatty fish (e.g herring, mackerel, salmon) per week
• Relevant allergy or known hypersensitivity against compounds of the study preparations
• Unstable medical illness or relevant history or presence of any medical disorder, potentially interfering with this study (e.g. volunteers having experienced any cardiovascular events such as infarction, angina, surgical endocoronary intervention, stroke in the last 6 months or psychiatric disorders / psychoactive medication)
• Clinically relevant abnormal laboratory, ECG, vital signs or physical findings at screening
• Intake of medication potentially interfering with this study
• Known malabsorption / maldigestion
• Drug-, alcohol- and medication abuses
• Known HIV-infection
• Known acute or chronic hepatitis B and C infection
• Blood donation within 2 weeks prior to study start (day 1) or during study
• Participation in any other clinical study within the last 30 days prior to study start or during the study
• Any other condition that, based on Investigator's judgement, makes the subject unfit for inclusion into study
• Anticipating any planned changes in lifestyle for the duration of the study

All participants and study staff were blinded to treatment allocations until the last patient had completed the last visit. The study capsules were identical in shape and color and packed in blisters tailor-made for each intervention group.