Trace Metabolic Functions Minerals

The only known function of iodine is that it aids in the formation of thyroid hormones, which help regulate cell activities. It is found mainly in clams, lobsters, shellfish and seafood, plants grown near the sea and foods with iodine added (iodised) salt. Selenium is the major mineral antioxidant and is required for many processes in the body. Vitamin E and selenium reinforce one another and can make up for one another if one is deficient. Selenium works well to help sun-damaged skin. Research also shows it can possibly help prevent viruses attacking the heart and lowers the risk of many cancers. Selenium is found in shellfish and meat as well as whole grains, but soils are often deficient in selenium, and the sulphur content in many fertilisers can also inhibit plant absorption.Selenium should be taken every day as an aid to fight oxidative free radicals that cause premature aging and stress. Low levels of selenium are also associated with mood disorders, degenerative diseases, thyroid problems, psychiatric disorders, poor immune functions and skin conditions.Copper helps promote bone growth and maintains the health of nerve tissue. Iron, copper and cobalt work closely together in the production and maturation of red blood cells. It is found in beef, liver, seafood, nuts, dry roasted cashews, dried beans and sunflower seeds.

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Measures to alleviate jet lag

 Certain food constituents seem to have effects on rhythm adjustment. A high carbohydrate low protein meal, facilitating brain uptake of tryptophan and its conversion to serotonin, may induce drowsiness and sleep. On the other hand, a high protein low carbohydrate meal, which enhances tyrosine uptake and convertsion to noradrenaline, increases levels of arousal. Moreover, programmed use of theophylline and caffeine can speed rhythm readaptation and help to raise arousal levels in the morning. However, although studies on military personnel consuming such diets reported reduced sleep disturbance and less subjective feelings of fatigue in the days immediately after a transmeridian flight compared with controls, a clear link between diet and jet lag has not been formally established. Two studies have investigated the effects of light treatment on sleep patterns after flights. In the former, 19 subjects returning to the United States from Oriental or South Pacific localities (advance shifts of 6.5 to 10 hours) were instructed to expose themselves to either bright white light (2000 lux) or dim red light (<100 lux) for 2 or 3 hours on awakening in the morning for 3 days.” No differences were found between the group means for any sleep measure, but exposure to bright light early in the morning appeared to facilitate the consolidation of sleep into a single night-time episode.In the latter, four subjects were polysomnographically recorded before and after a flight from Tokyo to San Francisco (8 hour advance).” In San Francisco, the subjects were requested to go bed at 2300 hours and wake up by 1000 hours and were exposed for 3 consecutive days to either bright ( > 3000 lux) or dim ( <500 lux) light for 3 hours starting at 1100 hours (0300 hours Tokyo time). The bright light treatment seemed to be effective in accelerating circadian re-entrainment.However, the sparse number of field studies and the small sample population considered do not yet allow a clear judgment on the beneficial effect of bright light treatment for jet lag.61 In fact, the Consensus Report for Light Treatment for Sleep Disorders concluded that “much remains to be learned before procedures can be developed that are at once effective, reliable, and practical. For this to happen, optimal combinations of several light exposure parameters must be first defined and tailored to specific flight situations”.

Possible Mechanisms for Suppression of Testosterone Concentrations with Long Term Exercise

In female athletes menstrual disturbances have been found in association with lower bone density particularly at trabecular sites.Furthermore, stress fractures seem to be more common in women with amenorrhoea or oligomenorrhoea with a relative risk that is between two to four times greater than that of their eumenorrhoeic counterparts. There are few studies investigating the relation of testosterone levels to bone density and stress fracture risk in young male athletes. A recent case report described the clinical features of a 29-year-old male distance runner who presented with a pelvic stress fracture, greatly decreased bone density and symptomatic hypogonadotropic hypogonadism." Using this case as an index, the authors hypothesised that exercise– induced hypogonadotropic hypogonadism could be identified in male athletes by the presence of one or more specific risk factors which included the presence of sexual dysfunction, a history of fracture, and the initiation of endurance exercise before age 18 Years.

They compared concentrations of free testosterone and luteinising hormone in 15 male runners with one or more of the above risk factors and 13 runners with none of the risk factors. Only one of the runners in the first group was identified as having primary hypogonadism and there was no significant difference between groups for hormone concentrations. Bone density, however, was not measured in these runners and correlated with testosterone concentrations. From a clinical perspective, it is important to clarify that although some male athletes do present With reduced testosterone concentrations, these concentrations are generally still within the normal range for adult men. Therefore, detrimental effects on bone density may not be as dramatic as those described for women with athletic amenorrhoea in whom oestradiol concentrations are well below normal.