Skip to main content
Open Access Publications from the University of California

Nutrition Bytes

Nutrition Bytes bannerUCLA


Taps: The Dangers of Drinking Water

Hydration is considered to be an important aspect of nutritional health. Unfortunately, many water sources are low in beneficial magnesium and calcium and high in cancer causing arsenic and chlorination by-products. Current research indicates that bolstering the magnesium and calcium content in both bottled and tap water may reduce the risks of acute myocardial infarction and certain cancers. Also, eliminating arsenic and chlorination by-products could reduce the rate of colon, bladder, lung, and skin cancers. As long as water does not meet the research-backed standards of dissolved constituents, it is not clear whether drinking water is actually good for one's health.

Flushing Out the Truth: Could Dietary Fiber Really Be the Magic Bullet for Colon Cancer Prevention?

It has become near nutrition dogma that fiber plays a key role in maintaining one's overall health. Indeed, various studies have found a high fiber diet to be a key component in decreasing one's risk for various ailments, notably heart disease. However, the true nexus between cancer and fiber still remains largely unproven. Various studies have demonstrated that a diet high in fiber and unrefined foods exhibit an inverse risk to colon cancer. This widely accepted dietary truth was challenged recently, however, by a paper published in the New England Journal of Medicine. The Fuchs study, which tracked 88,757 women's fiber intake and their colorectal cancer rate over 16 years, revealed no gained benefits from dietary fiber in reducing risk for colorectal cancer and adenoma. It even detected an increased risk involving vegetable fiber. However, physicians and patients must interpret the study's results with caution and critical attention. Expanding knowledge regarding molecular role of nutrients indeed confirms that dietary components play a key role in physiological regulation. However, complex interactions between food components makes the prospect of finding that one single magic bullet extremely elusive. Therefore, it would still be prudent to recommend that one obtain a majority of his or her calories from plant sources until further clinical trials could be completed to further elucidate the role of diet in colon cancer.

Caloric Restriction and Aging: Eat Less, Live Longer

Caloric restriction (CR), which is defined as undernutrition without malnutrition, is the only experimental manipulation known to retard aging and increase survival of mammals. CR has been shown in repeated experiments to extend mean and maximum life span, decelerate the rate of aging, and inhibit the onset of a number of life-shortening diseases in laboratory animals. The complete mechanism of how CR produces these beneficial changes is not understood, but pathological and molecular observations have provided much information on the ways in which CR decelerates aging. The first theory is the reduction of oxidative damage to tissues. Free radical production damages tissues and produces many effects of aging. Antioxidants that are produced in youth decline with age and do not provide as complete protective effects. However, it was found that CR maintains youthful levels of many antioxidants and in this way, aids in the prevention of aging. CR also elevates Hsp70, a heat shock protein that responds to pathological and environmental stresses like hyperthermia and ischemia. All living organisms show a reduced ability to respond to stress as they age which can be correlated to a decrease in heat shock protein transcription and expression. CR maintains youthful levels of HSP70 and perhaps via this mechanism, preserves the integrity of body and organs in response to stress. Another hypothesis is that CR extends life span by altering body metabolism and thereby decreasing the deposition of pathological fat in the body. Finally, CR is believed to prevent carcinogenesis by increasing apoptotic rates. Though these hypothesis are well supported, much more work must be done to get a complete picture of how CR extends life and inhibits aging. However, based on the strong evidence that CR reduces life-threatening disease and extends life, it would be a wise suggestion that we all practice moderation in our caloric intake.

The Role of Creatine Supplementation in Short Term Exercise and Medicine

Creatine phosphate (CP), the phosphorylated form of the amino acid creatine, plays an important role in regenerating adenosine triphosphate (ATP) in skeletal muscle. Oral supplementation can increase muscle stores of creatine and seems to have significant ergogenic benefit for short-term activities requiring strength and power. Recently, supplementation has been implicated in having medical benefits as well. It may prove useful for restoring contractility in acute heart failure, prevention of ischemic injury during heart surgery, keeping energy levels from dropping in patients with systemic infection by acting as an ATP buffer, and treating patients with Duchenne's muscular dystrophy. However, despite the potential benefit of creatine supplementation, the safety issues have not been sufficiently examined. There does not seem to be any deleterious effects associated with short-term creatine use except for reported cramping, muscle tears, dehydration, and nausea. One potential-long term risk may be down-regulation of the expression of the creatine transporter protein. The safety of creatine supplementation needs to be further examined in order to deter misuse and abuse.

Grapefruit Juice and Some Oral Drugs: A Bitter Combination

Grapefruit juice has been found to interact with many oral drugs when taken concomitantly. Studies have shown that grapefruit juice inhibits cytochrome P450 3A4 (CYP3A4)- an important enzyme involved in drug metabolism- via mechanism-based inactivation. Drug elimination is therefore prevented, and as a result, the bioavailability of many orally administered drugs is substantially increased when the patient ingests grapefruit juice. The grapefruit-drug interaction may result in severe side effects, ranging from hypotension to fatal cardiac arrhythmias. The active ingredients in grapefruit juice are substances of the coumarin family, primarily 6'7'-dihydroxybergamottin (DHB), a compound that inhibits CYP3A4 by causing irreversible inactivation of the enzyme. A flavenoid, naringenin, is also though to play a minor role. Furthermore, the effects of grapefruit juice can last over 24 hours since last consumption. Because many drugs, including felodipine, terfenadine, cyclosporine, and saquinavir, are metabolized by CYP3A4, it is very important to be aware of the potential side effects if grapefruit juice is consumed while patients are on medications that are metabolized by this enzyme.