根据最新一期Internal Medicine期刊中的报导，适当摄取微量元素硒（selenium）能够降低HIV侵袭的比率。
根据统计，抗反转录病毒疗法（antiretroviral therapy，ART）是目前能够增加HIV感染者存活期望值稍长的方式。然而，抗反转录病毒疗法是透过抑制HIV在患者体内的复制的状况，进而减少体内HIV数量。在这过程当中，不仅药物有毒害身体的问题，也有造成代谢官能不良障碍等疑虑。
美国迈阿密大学的研究者Barry E. Hurwitz博士，设计了有262位HIV感染受试者的双盲、随机并附有对照实验，藉由抽血检验硒含量、免疫T细胞上的CD4数量与HIV病毒读数（HIV viral load）来详加观察是否具有疗效。
研究者给予141位HIV感染者补充200微克的微量元素硒持续18个月，结果，服用硒的受试者在九个月后明显提高了CD4的数量，并且HIV病毒读数大量降低。「虽然详细的机制目前不明，」研究者表示：「但我们推测，足量的硒应能抑制病毒的复制。」
这项研究为抗病毒疗法开启了新的里程碑，也为日益增加的AIDS病患带来更多希望。
相关英文原文：
Selenium Supplements May Slow Progression of HIV
By Steven Reinberg, HealthDay Reporter
MONDAY, Jan. 22 (HealthDay News) -- Supplements of the mineral selenium appear to reduce or slow the progression of HIV, University of Miami researchers report.
Deficiencies in selenium have been noted in HIV-positive patients, and evidence suggests that supplements of the nutrient can improve immune system function, the researchers report in the Jan. 22 issue of the Archives of Internal Medicine.
"Those individuals who were treated with selenium displayed no further progression of HIV disease, whereas those who were on placebo evidenced a continued increase in HIV viral load," said lead researcher and professor of psychology Barry E. Hurwitz.
Another expert said the importance of the findings should not be overstated, however.
"That a cheap micronutrient might help blunt the short-term progression of HIV infection is wonderful news and can offer an intervention for persons in care settings who are not yet eligible for, or do not yet have access to, potent antiretroviral therapies," said Dr. Sten H. Vermund, the Amos Christie Chair and director of the Vanderbilt Institute for Global Health at Vanderbilt University in Nashville, Tenn.
However, he stressed that "by no means is selenium a treatment alternative, as the authors state, since the magnitude of benefit pales in comparison to that of antiretrovirals." Vermund was not involved in the study.
In the study, Hurwitz and colleagues randomly assigned 262 patients infected with HIV to 200 micrograms of selenium per day or placebo. Over the first nine months of the trial, the researchers monitored the patients' CD4 immune T-cell count (a measure of immune system health) and HIV viral load (the number of copies of the HIV virus in the blood).
They found that, among the 174 patients who completed the trial, those receiving the selenium supplement had reductions in their HIV viral load and increases in their CD4 count compared with those taking placebo. Among those taking placebo, viral load continued to increase, and CD4 counts continued to decline, Hurwitz said.
Improvements linked to selenium supplementation were seen whether patients were taking HIV antiretroviral drugs or not, Hurwitz said. "The impact of selenium was seen over and above anti-HIV medications," he said.
The trial continued for another nine months beyond the results in the current study. Data from the last nine months of the trial showed continued suppression of HIV among those patients taking selenium, Hurwitz said.
There is a tremendous challenge in the treatment of HIV patients using conventional medications to achieve and maintain suppression of the disease, Hurwitz noted. "Taking one capsule of selenium a day is a simple and inexpensive and safe therapy that can be used, not as a replacement for HIV drugs, but as an adjunct therapy," he said.
Hurwitz believes that taking selenium can be particularly effective in HIV patients who don't adhere closely to their medications regimens. "Selenium could be a very important advance in adjunct therapy," he said.
Selenium has many unique qualities, he added. "It has many beneficial aspects that affect our health," Hurwitz said. "There have been findings that it may be beneficial to our immune system, and it is a highly potent antioxidant."
"Selenium is available, and it's ready to be implemented right now," Hurwitz added. "It's a simple, inexpensive adjunct therapy, and I think it's ready to have an impact right now."
One expert said the study did have some drawbacks, however .
"Most of the study subjects are African-American men, most are on antiretroviral therapy, and most have low or undetectable viral loads," noted Dr. David Margolis, a professor of medicine, microbiology and immunology and epidemiology at the University of North Carolina at Chapel Hill. Also, "many of the study subjects are lost to follow-up, potentially introducing unforeseen bias into the findings," Margolis said.
Most important, the relevant benefit -- increased CD4 cell count -- attributed to selenium is rather small, he said. "Further, the CD4 cell count of the study group has already been sufficiently reconstituted by antiviral [drug] therapy to prevent most clinical problems. While it is possible that selenium supplementation reduces the frequency of failure of antiviral therapy, much better evidence would be needed to prove this," he said.
It would be interesting to show that selenium slowed the progression of HIV disease in patients with high CD4 counts -- a group that currently might not be offered antiviral therapy, Margolis said. "Strategies to safely delay antiviral therapy would be welcomed by many patients and providers," he said.
But too much selenium can also harm patients, Margolis added. In fact, in very large doses, supplementation can be fatal.
"The tolerable upper level is said to be 400 micrograms a day for adults, and the average U.S. diet contains about 100 micrograms a day," Margolis said. "There is also some evidence that selenium may blunt the protective effect of statins in slowing cardiovascular disease, so patients on therapy for lipid disorders might wish to avoid selenium supplementation until there is better evidence that it is beneficial," he said.
More information
Find out more about HIV/AIDS at the U.S. National Institute of Allergy and Infectious Disease.
SOURCES: Barry E. Hurwitz, Ph.D., professor, psychology, University of Miami; Dr. David Margolis, M.D., professor, medicine, microbiology and immunology, epidemiology, University of North Carolina at Chapel Hill; Sten H. Vermund, M.D., Ph.D., Amos Christie Chair and director, Vanderbilt Institute for Global Health, Vanderbilt University, Nashville, Tenn; Jan. 22, 2007, Archives of Internal Medicine
