Astaxanthin Reduces Hypertension
Epidemiological and clinical data suggest that dietary carotenoids such as astaxanthin may protect against cardiovascular disease (CVD) which includes hypertension. This condition is associated with blood vessel dysfunction, altered contractility and tone; mediated by relaxant (nitric oxide NO; prostacyclin) and constrictor factors (thromboxane; endothelin) in the blood. Furthermore, blood flow properties serve an important role in the pathological complications seen in atherosclerosis and coronary heart disease. Research presented here suggests that astaxanthin may be useful as part of an antioxidant therapy to alleviate hypertension (Figure 1).
Figure 1. Mechanisms by which Astaxanthin reduces hypertension
Reduction of Arterial Blood PressureAn early study involving a composition of carotenoids have been used against hypertension or high blood pressure (BP), but Hussein et al., (2005a) published the first study involving astaxanthin with spontaneously hypertensive rats (SHR) and stroke prone (SHR-SP). This study investigated the effects of astaxanthin on the aortic vessel blood pressure (BP) in relation to endothelium and nitric oxide (NO) to elucidate mechanism and response.
Figure 2. Astaxanthin (5mg/kg/day) treated SHR reduced mean blood pressure. Hussein et al., 2005b.In a double blind controlled placebo study conducted in Japan, 20 healthy postmenopausal women, who ingested 12 mg everyday for 4 weeks, reduced their systolic and diastolic blood pressure by 7% and 4%
In another study, 15 healthy subjects, between 27-50 of age, who received 9mg/day of astaxanthin for 12 weeks had their diastolic blood pressure decreased by 6% (Matsuyama et al., 2010).
A series of animal studies have largely replicated the effects of astaxanthin found in human studies (Ruiz et al., 2010; Preuss, 2009; Preuss, 2011).
Figure 3. Open Label Clinical Study. 73 subjects between 20-60 years of age received 4mg of astaxanthin x day for 4 weeks (Sato et al 2009)
Mechanism of Anti-hypertensionThe antihypertensive mechanism may be in part explained by the changes of vascular reactivity and hemorheology.
Microchannel Array Flow Analysis (MC-FAN) measured a significant increase of blood flow of 11% (Figure 3) in the astaxanthin treated group.
Figure 4. Open Label Clinical Study 35 healthy postmenopausal women (BMI 22.1) were included in the study, treated with astaxanthin daily dose of 12 mg for 8 weeksIn a human study conducted by Iwabayashi et.al., (2009) , 20 healthy women who ingested 6mg / day for 8 weeks increased ABI (ankle brachial pressure index) by 4% suggesting a reduction of lower limb vascular resistance. Another human study also prove that oral administration of 6 mg/day of astaxanthin for 10 days enhanced capillary blood flow by 10%.
Figure 5. Astaxanthin (6 mg/day) supplementation for 10 days improves blood flow in humans as tested by MC-FAN. Miyawaki et al., 2005.
Figure 6. Astaxanthin increases relaxant and reduces constrictor mechanisms to help reduce blood pressure in SHR.
Figure 7. A) Coronary artery wall is thinner and lumen is wider in astaxanthin treated rats. B) Elastin bands are also fewer in number and less elastic compared to the control groups which also show intense and branched elastine feature (C). Hussein et al., (2006a).
OutlookThe oxidative status and physiological condition during hypertension are successfully mediated by astaxanthin. The mechanisms of action include improved blood rheology, modulation of constrictor and dilator factors and blood vessel remodelling. Although, these findings are based on spontaneous hypertensive rat models, these serve as a solid basis for extending the hypothesis to human clinical trials.
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CCRES special thanks to
Mr. Mitsunori Nishida,
President of Corporate Fuji Chemical Industry Co., Ltd.
Croatian Center of Renewable Energy Sources (CCRES)