The December, 2008 issue of the journal Experimental Physiology published the discovery of researchers at the University of Illinois of an anti-inflammatory effect for vitamin E in an animal model of inflammation.
Scientists are becoming increasingly aware of the role of inflammation in a number of diseases and conditions. Chronic inflammation of the skeletal muscles in humans is a cause of significant physical impairment. Antioxidants such as vitamin E have been shown to reduce proinflammatory cytokine expression in cell culture studies, but the vitamin's effects had not been tested in the heart and skeletal muscle of mice with induced systemic inflammation.
University of Illinois kinesiology and community health professor Kimberly Huey and colleagues administered vitamin E or a placebo to mice for three days before injecting the animals with a low dose of E. coli lipopolysaccharide to induce inflammation. A control group received saline injections.
The team found increased levels of the cytokines interleukin-6 (IL-6) and interleukin-1beta (IL-1beta) in the skeletal and cardiac muscle of mice that received lipopolysaccharide, yet among those that received vitamin E, levels of these cytokines were significantly lower than those of the placebo group. The cytokines function as intercellular communicators which assist in immune response, yet can lead to excessive inflammation. Additionally, the researchers observed decreased activation of nuclear factor kappa-beta (another agent involved in inflammation) in mice that received vitamin E.
"The mice were administered vitamin E for three days prior to giving them what amounts to a minor systemic bacterial infection," Dr Huey explained. "One thing we did – in addition to (looking at) the cytokines – was to look, in the muscle, at the amount of oxidized proteins. Oxidation can be detrimental, and in muscle has been associated with reduced muscle strength."
Dr Huey revealed that "there was a significant reduction in the amount of lipopolysaccharide-induced oxidized proteins with vitamin E compared to placebo."
"So that's a good thing," she noted. "Potentially, if you reduce the oxidized proteins, that may correlate to increased muscle strength."
In previous research conducted by team member Rodney Johnson, an association in mice between vitamin E supplementation and reduced brain inflammation was observed. Inflammation in the brain is associated with Alzheimer's disease in humans.
Dr Huey concluded that vitamin E "may be beneficial in individuals with chronic inflammation, such as the elderly or patients with type II diabetes or chronic heart failure."
"This is clearly an animal model so whether it would translate to humans still requires a lot more research," she remarked. "Vitamin E is a supplement that is already approved, and these results may suggest an additional benefit of taking Vitamin E beyond what's already been shown."
Related Health Concern: Chronic inflammation
In aged people with multiple degenerative diseases, the inflammatory marker, C-reactive protein, is often sharply elevated, indicating the presence of an underlying inflammatory disorder (Invitti 2002; Lee et al. 2002; Santoro et al. 2002; Sitzer et al. 2002). When a cytokine blood profile is conducted on people in a weakened condition, an excess level of one or more of the inflammatory cytokines, e.g., TNF-a, IL-6, IL-1(b), or IL-8, is usually found (Santoro et al. 2002).
Scientists have identified dietary supplements and prescription drugs that can reduce levels of the pro-inflammatory cytokines. The docosahexaenoic acid (DHA) fraction of fish oil is the best documented supplement to suppress TNF-a, IL-6, IL-1(b), and IL-8 (Jeyarajah et al. 1999; James et al. 2000; Watanabe et al. 2000; Yano et al. 2000). A study on healthy humans and those with rheumatoid disease shows that fish oil suppresses these dangerous cytokines by up to 90% (James et al. 2000).
Other cytokine-lowering supplements are DHEA (Casson et al. 1993), vitamin K (Reddi et al. 1995; Weber 1997), GLA (gamma linolenic acid) (Purasiri et al. 1994), and nettle leaf extract (Teucher et al. 1996). Antioxidants, such as vitamin E (Devaraj et al. 2000) and N-acetyl-cysteine (Gosset et al. 1999), may also lower proinflammatory cytokines and protect against their toxic effects.