The Renin-Angiotensin-Aldosterone System (RAAS) is involved in blood pressure regulation and electrolyte balance. Angiotensin-converting enzyme (ACE) is a critical regulator of RAAS by cleaving angiotensin (Ang1) to Angiotensin2 (Ang2), which is the most powerful biologically active product of RAAS [1]. In the same context, angiotensin-converting enzyme 2 (ACE2) converts Ang2 to Ang (1-7), which is a vasodilator, antithrombotic, and antihypertrophic peptide [2]. ACE2 which is found in many tissues [3] has opposite effects to ACE on the heart, kidneys, and lungs [4]. Many pathological conditions, in particular cardiovascular disease (CVD), have shown a link between a disturbance in ACE/ACE2 ratio and the downregulation of ACE2 levels [5]. Also, ACE/ACE2 has been reported to be higher in moderate to severe chronic heart failure [6] as well as systolic blood pressure [7]. Recently, an elevated ACE/ACE2 ratio is linked to Coronavirus disease 2019 (COVID-19). SARS-COV2 enters target cells by binding of the spike protein to ACE2 and a specific transmembrane serine protease 2 (TMPRSS2) for the spike (S) protein priming, which also leads to downregulation of ACE2 [8]. Down-regulation of ACE2 caused by Coronavirus may have a potential role in the pathogenesis of COVID-19 infection. Accordingly, people with a higher ACE/ACE2 ratio may be more at increased risk of worse Covid-19 consequences [9].

On the other hand, omega-3 fatty acids could decrease CVD risk by their anti-inflammatory anti-thrombotic function [10]. A meta-analysis comprising 15,806 patients, showed that omega-3 fatty acids associated with a 30% reduction in fatal myocardial infarction and sudden death, in addition to a 20% reduction in overall mortality [11]. To the best of our knowledge, no clinical trials have evaluated the effect of omega-3 supplementation on serum ACE/ACE2 ratio which is recently ascribed as a potential key in 2019 Covid-19 as well as CVD [5,9].

Inclusion Criteria:

• Inclusion criteria included males and females in the age range of 35-65 years without a medical diagnosis of COVID-19 infection.

Exclusion Criteria:

• Any subject with any chronic disease such as CVD, diabetes, or immune problems, including autoimmune diseases, chronic or severe infections was excluded.
• Pregnant, breastfeeding, and females using hormonal contraceptives were excluded.