这几天到处可见关于锯棕榈生发水用来治疗雄性秃的新闻，每当有这类的新闻时，大家再心里最常提出的一个问题，就是‘有没有效’?要怎样去看待锯棕榈改善雄性秃这件事呢?我们试着以客观的角度来给大家一些意见。

锯棕榈籽粹取(saw Palmetto Berry Extract / SPE)，或称棕榈树果实(serenoa repens)，学名叫做Permixon，百年前就被印地安人用来改善摄护腺分面的问题，欧美也广泛应用在摄护腺症状的改善与预防上。所以，他并非是所谓的新药，且对于雄性秃朋友来说，也是早已熟知的成份了，只是现在再经由媒体的介绍，也让更多人能够去了解他的用途了。

有效、无效?

若是 有雄性秃掉发，大概就要接受头发会慢慢离家出走的窘境，且必须要认知到，一旦停止治疗，头发就会逐渐掉落到治疗前的样子，甚至更严重的事实，也因此，我们 总希望有一样药品或是非药品是能够有效治疗雄性秃的，但是事实上却不是如此。不论柔沛与落建，都只是可以缓和掉发与再生部分头发，而无法长回全部的头发， 原因在于无法100%阻断DHT荷尔蒙对毛囊的影响，口服或是外用的锯棕榈，也是如此;即便是使用之后有效，也一样要不间断的。

有些 人说，锯棕榈没有医学根据，也是一种偏方;有些人说，锯棕榈的确可以改善雄性秃，这样两极的褒贬，在我看来是没有意义的。我们可以举出好几篇的学术论文来 证明锯棕榈可以降低DHT，我们也可以紧守医学标准，非FDA许可的产品不用，非得坚持Minoxidil、Finasteride、雷射梳或是植发手术 不可。 Anyway，就让这两派说法继续坚持己见好了，我只想为有雄性秃困扰的朋友，找出多一个可行的方案。

锯棕 榈萃取物，也已经被证实可以有效减少毛囊细胞受体与DHT的结合，这实在勿需争议;也因此有些生技公司会用来研发含有SPE的头皮配方，并也确实具有阻断 DHT的功效。回到老问题身上，一定有效?多有效?怎么预期效果?那当然还是要看自己掉发的情况如何。如果是初期的雄性秃，外用锯棕榈不失为一个非药物的 替代方案，合理的预期效果一样是缓和掉发或是长回部份头发，当然也可能效果不彰。如果已经是较为严重的雄性秃(四期以上)，那锯棕榈也不可能有明显的效果 了。此外，锯棕榈若用来搭配落建若是柔沛(波斯卡)，也有相辅相成之效，但就要先衡量自己的经济能力了。

外用?口服?

如果 柔沛或波斯卡让人产生恼人的副作用时，口服锯棕榈可用来在替代药物上;也可以用来做初期的预防，毕竟没有人会先吃药来预防雄性秃的发生;或者是在治疗初 期，不想这么早服用口服药。但市面上的这些产品，通常会多添加其他可以用来阻断DHT的成分，如非洲刺梨(Pygeum)、绿茶中的儿茶素 (Catechins)等，价格也会比单一成分的锯棕榈来的高一些，且来源地多是以美国为主。至于副作用部份，口服锯棕榈的副作用机率极少，在一个315 人的研究中发现(D. Authie and J. Cauquil. A multicenter study of the efficacy of Permixon in daily practice. Pharmacol Clin; 5(56):3-13, 1987)，98%的服用者并没有副作用产生，而最常见的副作用症状多半为反胃或是轻微头痛，口服锯棕榈为脂溶性，最好在进餐时服用，大概一到两个小时就 会被吸受。

至于 外用锯棕榈，其实在一些养发液上都可以见到，美国品牌的 Revivogen(中译.立发健)、Hairgenesis(中译.发源)、Crinagen(中译.快来俊)，欧系品牌的护蕾(Ducray)、 Phyto(发朵)，这些产品的特性、效果优劣、价格高低也都具有差异性的。此外，锯棕榈萃取多半只是养发液其中多种成分之一而已，并非是单一成分的产 品。这类外用产品如果应用得宜，可以用来弥补口服药在抑制DHT效果的不足，或是用来搭配落建生发水，可以在外用的治疗方式上，获得更好的预期效果。但要 注意的是，SPE本来就是一种油性物质，必须要能够找出适合自己生活作息的使用方式，才能兼顾长期使用的稳定性。另外，SPE的副作用机率同样较低，可能 会有头皮过敏的可能(红肿痛痒)。

外用锯棕榈的效果在实证上，确实是比口服锯棕榈更加完整可信的，尽量以外用为首选，但外用产品毕竟是比口服麻烦一些，要能够耐心使用才有意义。总之，我们都可以跟自己的需求来决定要口服还是外用啰。

我要用吗?

要不 要使用，在于个人选择。锯棕榈的优点是副作用低，也不会有男性功能障碍，让我们在阻断DHT荷尔蒙上，有更多且更弹性的选择方式。至于钜棕榈的缺点则是需 要有更大规模的临床资料来证实其效度与信度。我还是想提醒大家，不是新闻报等之后，就表示一定有效，还是要认清自己的需求、充分了解锯棕榈特性与合理预期 效果，才能有效利用锯棕榈来改善雄性秃啰。

外用SPE的学术论文

1. Human prostatic steroid 5 alpha-reductase isoforms--a comparative study of selective inhibitors.

This study suggests that Fenistride (active ingredient of Propecia) only inhibited the Type 2 form of 5 alpha reductase where Saw Palmetto extract inhibited both type 1 and 2 forms of 5 alpha-reductase and was more potent than Fenistride. J Steroid Biochem Mol Biol, 54: 5-6, 1995 Sep, 273-9

2. Testosterone metabolism in primary cultures of human prostate epithelial cells and fibroblasts.

This Study shows that Fenistride and 4-MA inhibited the formation of some testostrone Metabolites (including DHT), where as Saw Palmetto inhibited the formation of all the Testostrone metabolites studied. J Steroid Biochem Mol Biol, 55: 3-4, 1995 Dec, 375-83

3. The effect of Permixon on androgen receptors.

This study shows that Saw Palmetto extract was able to effectively reduce Binding of Testostrone and DHT to their receptors on various tissues. Acta Obstet Gynecol Scand, 67: 5, 1988, 397-9

4. Prager N, Bickett K, French N, Marcovici G. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. J Altern Complement Med. 2002 Apr;8(2):143-52

可参考资料--SAW PALMETTO From Dr.Raztec

This is by far the most commonly recognized and discussed herb concerning the prostate. Before we even begin its discussion, I highly recommend reading the book entitled "Saw Palmetto: Nature's Prostate Healer" by Ray Sahelian, M.D. This is a marvelous book that discusses the prostate and how Saw palmetto and other natural nutrients can prevent prostate disease (BPH).

Saw palmetto is a plant (dwarf palm tree) native to the United States. It has been used medicinally for over a century. Its first use was described in the medical literature in the 1800s. Early literature concerning Saw palmetto stated that it relieved symptoms ranging from prostate enlargement in men to gynecological problems in women, such as menstrual discomfort. It has even been described as a potential aphrodisiac.

Saw palmetto contains hundreds of different substances that can account for its beneficial effects. Saw palmetto is usually distributed as a crushed berry or as an extract. The extract form contains most of the substances found to be effective in treating benign prostatic enlargement. The extract form has been shown to be more potent than the dried berry form. The extract, then, is the form of choice.

There are many articles in the medical literature that establish the efficacy of Saw palmetto in treating benign prostatic hyperplasia. One of the most recent and prestigious articles is "Saw Palmetto Extracts for the Treatment of Benign Prostatic Hyperplasia: a Systematic Review" by Timothy J. Wilt, MD, MPH et al. It appeared in The Journal of the American Medical Association on November 11, 1998 [2]. The study clearly demonstrated that the use of Saw palmetto improved urinary tract symptoms associated with benign prostatic hyperplasia. It also demonstrated that Saw palmetto provided similar improvement in urinary tract symptoms when compared to drugs such as finasteride. Saw palmetto was associated with fewer side effects. Although the mean study duration (the period of time that participants were using Saw palmetto) was 9 weeks, participants were noticing positive results in as little as 4 weeks. Finasteride users commonly saw relief of symptoms after three months.

The next three paragraphs are a bit technical, but some readers may appreciate the detail. Others may wish to skip ahead to the paragraph that begins, “It is clear that….”

A total of 18 randomized controlled trials involving 2939 men who met inclusion criteria were analyzed. Treatment allocation concealment was adequate in 9 studies (i.e., they were single-blind tests), whereas 16 studies were double-blinded. The average duration of the study was 9 weeks. In comparison to the men in the placebo control group, men treated with the SP extract Serenoa repens (S. repens or Saw palmetto) showed a measurable improvement in urinary tract symptoms. The weighted average difference for patients treated with S. repens was -1.41 points with a 95% confidence interval of L2.52, -0.301, compared to the control group's weighted-mean difference of -0.76 with a 95% confidence interval of [-1.22, -0.32]. This represents a relative weighted mean difference of 46% (Here, a lower weighted-mean difference correlates with improved urinary tract function). The patients themselves provided self-improvement ratings in urinary tract symptoms that were highly correlated with their quantitative evaluations.

Compared with men receiving finasteride, men treated with S. repens showed similar improvements in urinary tract scores. The main advantage of treatment of BPH with S. repens over finasteride was apparent in the decreased incidence of adverse side effects. For example, 4.9% of patients treated with finasteride reported erectile dysfunction compared with 1.1% of patients treated with S. repens. These percentages are based on the Neyman-Pearson binary hypothesis test with power function parameter P set to P<0.001. That is, the probability of a Type-II error was fixed at 0.999. Here, a Type-II error refers to the probability of accepting the null hypothesis H_0 (no urinary tract improvement) when the alternative hypothesis H_1 (urinary tract improvement) is actually true. The significance level for all randomized trials was set at 0.05, thus indicating a probability of 0.05 of rejecting H_0 when H_1 is true.

Some key points regarding these results are in order here. First, since all the statistical studies are based on classical (or frequentist) methods, all inferences derived from them are inherently indirect. That is, no direct claims can be made regarding the probabilities of improved urinary tract function. Rather, one can only infer the probabilities that the treatment did not fail. This is by no means a fallacy, neither on the part of the researchers nor on the methods of data acquisition, but is an inherent aspect of frequentist analysis. To emphasize this point further, consider the value of the mean-weighted difference for patients treated with S. repens. The reported value was -1.41. Note that this is not a true statistical estimate of this parameter. Rather, it is a measured value that has a 95% probability of being contained in the random interval [2.52,-0.30]. If one wished to make direct inferences from the data, non-classical statistical analyses, such as those based on Bayesian decision theory, should be employed [3]. Another point worth mentioning concerns the sensitivities of the tests. Since the studies did not report the standard errors of the differences between the means of S. repens and control, the authors assessed the sensitivity of the tests by analyzing data for three different values of correlation coefficients, namely (0.25, 0.50, 0.75). The work, then, reported "no significant statistical difference in outcomes according to the three correlation coefficients." As a result, the correlation coefficient was arbitrarily set to 0.50. One could certainly argue that this is a somewhat ad-hoc approach. To be more precise and more objective, the correlation coefficient could have (and should have) been estimated by a standard technique such as the method of maximum likelihood [4] or via another point estimator such as the Bayesian minimum mean square error (MMSE) estimator or even the Bayesian maximum a-posteriori (MAP) estimator [5]. This would certainly have altered the calculated relative weighted mean difference from its reported value of 46%, but to what degree is unknown. Note that the relative weighted mean difference of 46% was not actually reported in the JAMA article [1] but rather was calculated by the current authors based on the results in [1].

It is clear that there was an improvement in patients given Saw palmetto over the placebo-control group, and, moreover, the improved urinary tract function paralleled that which was displayed by patients taking finasteride. This study clearly demonstrated that the use of Saw palmetto improved urinary tract symptoms associated with BPH, and that its effects were in concert with the improvements achieved through the use of finasteride. It was also shown that, compared to finasteride, Saw palmetto administration produced a lower incidence of adverse side effects. The mean duration of the study encompassed 9 weeks of Saw palmetto administration. However, many participants were reporting positive results in as little as 4 weeks.

Both Saw palmetto and finasteride were found to be effective in the treatment of benign prostatic hyperplasia (BPH). This study clearly establishes the role of Saw palmetto in combating the effects of DHT. Note that Saw palmetto was compared to 5 mg of finasteride in this study and that Propecia contains only 1 mg of finasteride.

Side effects experienced with Saw palmetto are infrequent. One three-year study with 315 patients showed that 98% of the patient population had no significant side effects [6]. The most common side effects experienced with Saw palmetto include nausea and mild headache. Since Saw palmetto is fat-soluble, it is better to take it with meals. It usually takes one to two hours to be absorbed.

References (relating to Saw palmetto)

1. Gormley GJ, et al. The effect of finasteride in men with benign prostatic hyperplasia. N Engl J Med;327:1185-1191,1992.

2. T.J. Wilt, A. Ishani, G. Stark, R. MacDonald, J. Lau, and C. Muirow. Saw Palmetto extracts for treatment of benign prostatic

hyperplasia.JAMA;280(18)1604-1609, 1998.

3. J. O'Berger, Statistical Decision Theory and Bayesian Analysis, 2nd Ed., Springer Verlag Series in Statistics, Springer,1985.

4. PJ. Bickel and K.A. Doksum, Mathematical Statistics -- Basic Ideas and Selected Topics, Prentice Hall, Englewood Cliffs, NJ, 1977.

5. A. O'Hagan, Kendall's Advanced Theory of Statistics, Volume 2B: Bayesian Inference, Halsted Press, New York, 1994.

6. D. Authie and J. Cauquil. A multicenter study of the efficacy of Permixon in daily practice. Pharmacol Clin; 5(56):3-13, 1987.