Spirulina in Clinical Practice: Evidence-Based Human Applications
Spirulina in Clinical Practice:
Evidence-Based Human Applications
2.1. Spirulina and Chronic Fatigue
2.2. Allergy, Rhinitis, and Immunomodulation
It has been well documented that Spirulina exhibits anti-inflammatory properties by inhibiting the release of histamine from mast cells [9, 10].
In a recent randomized, double-blind placebo-controlled trial [11], individuals with allergic rhinitis were fed daily, either with placebo or Spirulina for 12 weeks. Peripheral blood mononuclear cells were isolated before and after the Spirulina feeding and levels of cytokines (interleukin-4 (IL-4), interferon-γ (IFN-γ) and interleukin-2), which are important in regulating immunoglobulin (Ig)E-mediated allergy, were measured. The study showed that high dose of Spirulina significantly reduced IL-4 levels by 32%, demonstrating the protective effects of this microalga toward allergic rhinitis.
Ishii et al. [12] studied the influence of Spirulina on IgA levels in human saliva and demonstrated that it enhances IgA production, suggesting a pivotal role of microalga in mucosal immunity.
A Japanese team identified the molecular mechanism of the human immune capacity of Spirulina by analysing blood cells of volunteers with pre- and post-oral administration of hot water extract of Spirulina platensis. IFN-γproduction and Natural Killer (NK) cell damage were increased after administration of the microalga extracts to male volunteers [13].
In a recent double-blind, placebo-controlled study from Turkey evaluating the effectiveness and tolerability of Spirulina for treating patients with allergic rhinitis, Spirulina consumption significantly improved the symptoms and physical findings compared with placebo (P < .001), including nasal discharge, sneezing, nasal congestion and itching [14].
It is well understood that deficiency of nutrients is responsible for changes in immunity, which manifests as changes in production of T-cells, secretory IgA antibody response, cytokines and NK-cell activity. The above studies suggest that Spirulina may modulate the immune system by its role in covering nutritional deficiencies.
2.3. Antiviral Applications: In Vitro Studies
There are no in vivo studies providing strong evidence supporting the possible antiviral properties of Spirulina. The active component of the water extract of S. platensis is a sulfated polysaccharide, calcium spirulan (Ca-Sp). According to Hayashi et al. [15], Ca-Sp inhibits the in vitro replication of several enveloped viruses including Herpes simplex type I, human cytomegalovirus, measles and mumps virus, influenza A virus and human immunodeficiency virus-1 virus (HIV-1).
Another more recent study showed in vitro that an aqueous extract of S. platensis inhibited HIV-1 replication in human T-cells, peripheral blood mononuclear cells and Langerhan cells [16]. The advantage of using herbs and algal products with proven antiviral properties in fighting certain viruses is that they can be used—through immunomodulation—even when the infection is established.
Of course, the above promising effects need to be studied further in animal models and humans before any definitive conclusions are drawn.
2.4. Cholesterol-Lowering Effects and Effects on Diabetes
Cardiovascular disease remains the number one cause of death in developed countries, despite increased awareness, and high cholesterol is one of the most important risk factors in atherosclerosis.
Nakaya et al. [17], in the first human study, gave 4.2 g day−1 of Spirulina to 15 male volunteers and, although there was no significant increase in high-density lipoprotein (HDL) levels, they observed a significant reduction of high-density lipoprotein (LDL) cholesterol after 8 weeks of treatment. The atherogenic effect also declined significantly in the above group [17].
Ramamoorthy and Premakumari [18] in a more recent study administered Spirulina supplements in ischemic heart disease patients and found a significant reduction in blood cholesterol, triglycerides and LDL cholesterol and an increase in HDL cholesterol. More research is needed before Spirulina can be recommended to lower cholesterol levels but its role as a natural food supplement in combating hyperlipidaemia, in combination with other therapeutic options, should not be overlooked.
Finally, Mani et al. [19] in a clinical study, found a significant reduction in LDL : HDL ratio in 15 diabetic patients who were given Spirulina. However, this study was small and better studies are needed before Spirulina can be recommended in diabetes.
2.5. Anticancer Effects
It has been argued that the combined antioxidant and immune modulation characteristics of Spirulina may have a possible mechanism of tumor destruction and hence play a role in cancer prevention. Whilst there are many animal and in vitro studies, there has been only one trial with human subjects. This study looked specifically at the effects of Spirulina on oral carcinogenesis, in particular leukoplakia [20]. It is not surprising that few human studies exist to date as cancer prevention trials with lower cancer incidence as an endpoint have logistic problems, rendering them essentially impossible to conduct for most malignancies. The study conducted by Mathew et al. on a cohort of 77 patients originates from previous trials on hamsters that showed tumor regression after topical application or enteral intake of Spirulina extract [21–23]. They reported that 45% of their study cohort showed complete regression of leukoplakia after taking Spirulina supplements for 1 year. The authors also reported that there was no rise in the serum concentration of retinal β-carotene despite supplementation and concluded that other constituents within Spirulina may have been responsible for the anticancer effects. Whilst their results appear promising, it was an unblinded, non-randomized trial and as such cannot be regarded as evidence of a positive effect.
2.6. Chronic Arsenic Poisoning: A Randomized Trial
Millions of people in Bangladesh, India, Taiwan and Chile are consuming high concentration of arsenic through drinking water and are at risk of chronic arsenic poisoning for which there is no specific treatment. A placebo-controlled, double-blind study was conducted to evaluate the effectiveness of spirulina extract plus zinc in the treatment of chronic arsenic poisoning [24]. Forty-one patients with chronic arsenic poisoning were randomly treated by either placebo (17 patients) or spirulina extract (250 mg) plus zinc (2 mg) (24 patients) twice daily for 16 weeks. Each patient was supplied with arsenic-safe drinking water by installing a locally made water filter at household level. Effectiveness of spirulina extract plus zinc was evaluated by comparing changes in skin manifestations (clinical scores) and arsenic contents in urine and hair, between the placebo- and spirulina extract plus zinc-treated groups. Results showed that spirulina extract plus zinc twice daily for 16 weeks may be useful for the treatment of chronic arsenic poisoning with melanosis and keratosis. More randomized trials are required but the results are promising.
2.7. Antioxidant Effects: No In Vivo Studies
C-phycocyanin (C-PC) is one of the major biliproteins of Spirulina with antioxidant and radical scavenging properties. C-PC, a selective cyclooxygenase-2 inhibitor, induces apoptosis in lipopolysaccharide-stimulated RAW 264.7 macrophages. It is also known to exhibit anti-inflammatory and anticancer properties [25]. To date though, there are no in vivo human studies on possible antioxidant effects of Spirulina
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