Halperin Scott A, Smith Bruce, Nolan Coleen, Shay Janet, Kralovec Jaroslav
Department of Pediatrics, Dalhousie University and the IWK Health Centre, Halifax, NS.
CMAJ. 2003 Jul 22;169(2):111-7.
Enhancement of immune function has been claimed as a benefit of some natural health products, although few have been subjected to randomized clinical trials. We evaluated the effect of an oral dietary supplement derived from the edible microalga Chlorella pyrenoidosa on immune response after influenza vaccination.
We conducted a randomized, double-blind, placebo-controlled community-based clinical trial in a convenience sample of 124 healthy adults at least 50 years of age randomly assigned to receive the study product (200 or 400 mg of a Chlorella-derived dietary supplement) or placebo. Participants took the study product or placebo once daily for 28 days. On day 21, we administered a single dose of a licensed trivalent, inactivated influenza vaccine. We obtained serum specimens to measure hemagglutination inhibition titres before and 7 and 21 days after vaccination. The primary immunological outcomes were the proportion of participants with a 4-fold or greater increase in antibodies and geometric mean antibody titres after vaccination; the proportion of participants reporting adverse events during therapy was the safety outcome.
A total of 117 (94%) participants completed all aspects of the study. There were no differences in the proportions of recipients of 200 or 400 mg of the Chlorella-derived dietary supplement or placebo who achieved at least a 4-fold increase in antibodies (proportions for the 3 virus strains ranged from 17.9% to 28.2% for the 200-mg group, from 11.1% to 22.2% for the 400-mg group and from 19.0% to 21.4% for the placebo group; p > 0.05 for all comparisons). Reports of adverse events were similar for recipients of the supplement and placebo, except with regard to fatigue, which was reported more frequently by recipients of 200 mg of the supplement (18/41 or 44%) than by those who received 400 mg of the supplement (8/40 or 20%; p = 0.032) or placebo (8/42 or 19%; p = 0.019). Recipients of 400 mg of the supplement who were 55 years of age or younger had significantly higher geometric mean antibody titres against influenza A/New Caledonia 21 days after vaccination (p = 0.047) and against B/Yamanashi 7 days after vaccination (p = 0.034); the trends were nonsignificant for titres against A/Panama. We also observed similar increases for the proportions of subjects with a 2-fold or greater or a 4-fold or greater increase in antibodies.
The Chlorella-derived dietary supplement did not have any effect in increasing the antibody response to influenza vaccine in the overall study population, although there was an increase in antibody response among participants aged 50-55 years. Adverse events were similar among those receiving the supplement and the placebo. Further studies are warranted to explore the range of clinical effects resulting from ingestion of this dietary supplement.
一些天然保健品声称具有增强免疫功能的益处，尽管很少有产品经过随机临床试验验证。我们评估了一种源自可食用微藻蛋白核小球藻的口服膳食补充剂对流感疫苗接种后免疫反应的影响。
我们在一个便利样本中进行了一项随机、双盲、安慰剂对照的社区临床试验，该样本包括124名至少50岁的健康成年人，他们被随机分配接受研究产品（200毫克或400毫克的小球藻衍生膳食补充剂）或安慰剂。参与者每天服用一次研究产品或安慰剂，持续28天。在第21天，我们给参与者接种一剂已获许可的三价灭活流感疫苗。我们在接种疫苗前、接种后7天和21天采集血清样本，以测量血凝抑制效价。主要免疫结果是接种疫苗后抗体增加4倍或更多的参与者比例以及几何平均抗体效价；治疗期间报告不良事件的参与者比例为安全性结果。
共有117名（94%）参与者完成了研究的各个方面。接受200毫克或400毫克小球藻衍生膳食补充剂或安慰剂的参与者中，抗体至少增加4倍的比例没有差异（200毫克组针对3种病毒株的比例在17.9%至28.2%之间，400毫克组在11.1%至22.2%之间，安慰剂组在19.0%至21.4%之间；所有比较的p>0.05）。补充剂和安慰剂接受者的不良事件报告相似，但疲劳情况除外，接受200毫克补充剂的参与者报告疲劳的频率更高（18/41或44%），高于接受400毫克补充剂的参与者（8/40或20%；p = 0.032）或安慰剂组（8/42或19%；p = 0.019）。接种疫苗21天后，400毫克补充剂组中55岁及以下的参与者针对甲型/新喀里多尼亚流感病毒的几何平均抗体效价显著更高（p = 0.047），接种疫苗7天后针对乙型/山形流感病毒的几何平均抗体效价也显著更高（p = 0.034）；针对甲型/巴拿马流感病毒的效价趋势不显著。我们还观察到抗体增加2倍或更多或4倍或更多的受试者比例有类似增加。
在整个研究人群中，小球藻衍生的膳食补充剂对增加流感疫苗的抗体反应没有任何作用，尽管50 - 55岁的参与者抗体反应有所增加。接受补充剂和安慰剂的人群中不良事件相似。有必要进一步研究探索摄入这种膳食补充剂所产生的临床效果范围。
