December 1, 2000

(SACRAMENTO, Calif.) - Adding spirulina to cultured immune system cells significantly increases the production of infection fighting cytokines, say immunologists at UC Davis School of Medicine and Medical Center. Their finding is published in the Fall issue of the Journal of Medicinal Foods.

Spirulina are blue-green algae rich in antioxidants, vitamins, minerals and other nutrients. Used as a food supplement for more than 20 years, spirulina grows naturally in lakes with extremely high pH levels, but it is also harvested from large-scale commercial ponds, where purity is monitored before being dried and distributed in tablet and powdered form.

A number of animal studies have shown spirulina to be an effective immunomodulator (an agent that can effect the behavior of immune cells.) In rats spirulina inhibited allergic reactions by suppressing the release of histamine in a dose-dependent fashion. In cats, spirulina enhanced the ability of macrophages to engulf bacteria, and in chickens spirulina increased antibody responses and the activity of natural killer cells, which destroy infected and cancerous cells in the body.

While extensive human studies have not been done, several reports also suggest spirulina has therapeutic effects on hyperlipidemia and obesity. In one study, spirulina decreased total serum cholesterol and low-density lipoprotein cholesterol, while increasing high-density lipoprotein. A 1986 study of obese patients showed a significant reduction of body weight after including spirulina in the diet for four weeks. In the UC Davis study, researchers evaluated the secretion of the cytokines interferon-gamma, interleukin-4, and interleukin-1beta in the lab to get a better understanding of spirulina's potential regulatory effect on the immune system.

"We found that nutrient-rich spirulina is a potent inducer of interferon-gamma (13.6-fold increase) and a moderate stimulator of both interleukin-4 and interleukin-1beta (3.3-fold increase)," says Eric Gershwin, professor and chief of the Division of Rheumatology, Allergy and Clinical Immunology at UC Davis. "Together, increases in these cytokines suggest that spirulina is a strong proponent for protecting against intracellular pathogens and parasites and can potentially increase the expression of agents that stimulate inflammation, which also helps to protect the body against infectious and potentially harmful micro-organisms. Additional studies with individuals consuming spirulina are needed to determine whether these dramatic effects extend beyond the laboratory."

In the body, the preferential increase in the production of interferon-gamma over interleukin-4 would shift the immune system towards mounting a cell-mediated immune response instead of a humoral response. A cell-mediated response includes the activation of T-cells and antibodies that work with macrophages, another type of immune system cell, to engulf invading micro-organisms. Hence, spirulina's strength in protecting against intracellular pathogens and parasites. The moderate increase in the secretion of interleukin-1beta, a cytokine that acts on nearly every cell of the body to promote inflammation, works to support the overall immune response.

To evaluate the effects of spirulina on the immune system, the UC Davis immunologists collected blood samples from 12 healthy volunteers, separating out the peripheral blood mononuclear cells. These cells, which include macrophages, monocytes, and lymphocytes, including B and T cells, work as a team to mount an immune response. The researchers incubated these cell cultures with dilutions of spirulina made from 429 mg capsules of dried, powdered spirulina. They added phytohemoglutanin, a known stimulator of lymphoid cells, to half of cell cultures to assess spirulina's effect on the immune system at rest and when stimulated to mount an allergic response. After 72 hours, they measured changes in cytokine levels in all samples using ELISA analysis. (ELISA, or enzyme-linked immunosorbent assay, is a sensitive technique for accurately determining the amount of protein in a given sample.)

"People have used foods like yogurt and spirulina throughout history," says Judy van de Water, associate professor of rheumatology, allergy and clinical immunology at UC Davis. "Through research, we are learning exactly how these foods improve immune system function and how they are a beneficial addition to our diet."

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