Nutrition Bytes

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders. The efficacy of peppermint as an alternative medicine for the relief of IBS has been explored, both in vitro and in clinical settings, as it has the potential to provide inexpensive relief, along with lessened associated side effects of other drugs being used. Although in vitro studies show that peppermint has antispasmodic properties, most likely due to its ability to block smooth muscle calcium channels, clinical studies give mixed results. Some clinical studies have shown patients ingesting enteric-coated (Colpermin) peppermint capsules had a considerable reduction in associated IBS symptoms, while other studies have demonstrated that differences were not statistically significant. Metaanalysis of five clinical studies show that patient IBS relief was significant (p<0.001); however, flaws were found in individual studies (e.g., studies not being crossed over, not using the Rome (Manning) Criteria to determine if the person is diagnosed with IBS, etc.), making it difficult to recommend peppermint exclusively for the relief of IBS. Although the treatment of IBS with peppermint appears to be promising, additional, carefully planned studies need to be conducted to ensure that findings are significant.

High fat diets seem to improve exercise endurance in animals, although this effect is not uniformly found in humans. Enhancements in endurance appear to be due to physiological changes in skeletal muscles and their milieu, including increased fat oxidative capacity, increased plasma free fatty acid levels, greater mitochondrial density, and increased activities of b -hydroxy-acyl-CoA-dehydrogenase (b -HAD) and citrate synthase. Glycogen may also be spared by posttransformation regulation of glycogen phosphorylase. High fat diets may have a more powerful effect in animals because the diets in animal experiments were typically more extreme than those given to humans.

Osteoarthritis results from the progressive degeneration of joint cartilage proteoglycans caused by an imbalance of their synthesis and degeneration. Standard therapies simply treat the symptoms of the disease and may intensify cartilage catabolism. Glucosamine stimulates the production of proteoglycans by acting as a substrate for glycosaminoglycan synthesis, bypassing the normal rate-limiting step in the pathway. Animal studies have demonstrated the ability of glucosamine to stimulate proteoglycan and collagen synthesis and inhibit the breakdown of cartilage. Clinical trials have shown the therapeutic benefits of glucosamine in improving pain and mobility in osteoarthritis without significant side effects. These benefits are equal to or greater than those seen with standard therapies, without the risks associated with their long-term use. Glucosamine thereby appears to offer a practical alternative to standard osteoarthritis treatment.

Folate and vitamin B12 deficiency manifests in a number of known hematological and neurological disorders. Recently, an association has been discovered between these nutrients and Alzheimer's disease (AD). Although the initial evidence suggested that vitamin B12 levels may be reduced in AD patients, a number of studies failed to establish a consistent association between global deficiency in B12 and folate with this disease. However, more careful analysis of the biochemistry of these vitamins has revealed consistent metabolic abnormalities in Alzheimer's patients. The presence of elevated methylmalonyl-CoA and homocysteine levels in AD patients has suggested a number of interesting mechanisms by which they may play a role in the pathogenesis of dementia. There is currently a lack of consensus, however, as to whether these metabolic abnormalities represent an etiological factor or simply a consequence of the disease process.

The value of zinc cold therapy remains unsettled. Studies investigating the therapeutic effectiveness of zinc in the treatment of the common cold have produced conflicting results. This paper presents the findings and weaknesses of the pioneering and most current studies of zinc cold therapy in an effort to furnish a clearer picture of the action of zinc in fighting the common cold and identify necessary design modifications for future trials.

Lycopene is an acyclic hydrocarbon carotenoid containing 11 conjugated double bonds in the all-trans form. It lacks provitamin A activity, but has an exceptionally high singlet oxygen quenching ability. Carotenoids are lipid-soluble, transported in the blood by lipoproteins and appear to concentrate in tissues where lipoprotein uptake is high, as in the adrenals, testes, liver, kidney, and prostate. Increased plasma concentrations of lycopene have been shown to elevate lycopene metabolites and reduce lipid, protein, and DNA oxidation. Lycopene predominantly occurs in fresh tomatoes and tomato products such as tomato juice and tomato sauce. Its bioavailability is increased in cooked or processed tomato products and when consumed with oils. Epidemiological studies of lycopene and cancer have correlated increased tomato intake with lower incidence of gastrointestinal, stomach, and prostate cancers while decreasing serum values of lycopene increases the risks for various types of cancer. Lycopene is an effective inhibitor of cell growth and DNA synthesis in human cancer cell cultures and suppresses mammary tumor development in SHN mice and DMBA rat tumor models.

Pyruvate and dihydroxyacetone (DHAP) are marketed as nutritional supplements by health food stores and multilevel marketing distributors. Claims for pyruvate and dihydroxyacetone range from increasing endurance capacity, augmenting weight and fat loss, decreasing appetite, increasing metabolism, acting as an antioxidant, and lowering plasma lipids. Although several laboratory and clinical studies have investigated these claims, no studies to date have demonstrated the effectiveness of DHAP in improving athletic performance.