Diet and dermatology
The role of dietary manipulation in the prevention and treatment of cutaneous disorders
饮食疗法在预防和治疗皮肤疾病中的作用
英文原文
The role of diet (and specifically nutrition, vitamins, and “health foods”) in disease prevention and treatment has become the basis of lay press releases, cover stories in magazines and newspapers, and new research. In an attempt to ward off diseases, including cancer, heart disease, and the manifestations of aging, the public and scientists around the world have begun to question the efficacy and safety of dietary manipulation and vitamin ingestion. Historically, nutrition has been neglected in medical education; dietary fads have been regarded by physicians with skepticism. With mounting evidence that vitamin supplementation and alterations in diet may be therapeutic and relatively safe, we reviewed the impact of diet on some cutaneous diseases such as skin cancer, wound repair, and inflammatory dermatoses. Well-recognized associations of cutaneous disease and dietary factors (e.g., atopic dermatitis and food allergy; psoriasis and fish oil, vitamin D, and vitamin A;dermatitis herpetiformis and gluten) have been reviewed well elsewhere and have not been considered extensively in this review.
对应中文
饮食（尤其是营养、维生素和“健康食品”）在疾病预防和治疗中的作用已成为日常新闻稿、杂志和报纸封面故事以及最新研究的基础。为了预防疾病，包括癌症、心脏病和衰老，世界各地公众和科学家开始质疑饮食操作和摄入维生素的有效性和安全性。从历史上看，医学教育忽视了营养；饮食潮流一直受到物理学家的怀疑。越来越多的证据表明，补充维生素和改变饮食可能具有治疗性，并且相对安全，我们回顾了饮食对一些皮肤疾病的影响，如皮肤癌、伤口修复和炎症性疾病。皮肤病与饮食因素的公认关联（例如，特应性皮炎和食物过敏；银屑病和鱼油、维生素D和维生素A；疱疹样皮炎和谷蛋白）在其他地方得到了很好的审查，但在本审查中没有得到广泛考虑。
NONMELANOMA SKIN CANCER
非黑色素瘤皮肤癌
β-Carotene
β-胡萝卜素
英文原文
β-Carotene, the essential precursor to vitamin A or retinol, functions as a free radical scavenger, protecting plants from UV light-induced damage to which they would be especially vulnerable because they contain the photosensitizer, chlorophyll. The average daily consumption of β carotene is approximately 1.5 mg/day, Major dietary sources include spinach, carrots, sweet potatoes, squash, and cantaloupe melons. The U.S. Department of Agriculture and the National Cancer Institute suggest that Americans alter their diet so that the daily β-carotene intake reaches 5.6 to 6.0 mg.
对应中文
β-胡萝卜素是维生素A或视黄醇的必要前体，其功能是清除自由基，保护植物免受紫外线的伤害，因为它们含有光敏剂叶绿素，因此特别容易受到紫外线伤害。β胡萝卜素的平均日摄入量约为1.5毫克/天，主要的饮食来源包括菠菜、胡萝卜、红薯、南瓜和甜瓜。美国农业部和国家癌症研究所建议美国人改变饮食，每天β胡萝卜素的摄入量达到5.6至6.0毫克。
英文原文
The recommendation to increase carotenoid intake is based on studies that show an increased risk of lung cancer in persons with a low rate of consumption of vegetables rich in β-carotene.A similar inverse relation has been demonstrated between plasma β-carotene levels and the risk of lung cancer as well as the risk of death from all types of cancer. In addition, research in laboratory animals has determined that treatment with oral β-carotene inhibits the development of chemically induced and UV light-induced skin cancers. However, although epidemiologic data for lung cancer support the possible protective effect of high β-carotene consumption, the evidence is lacking for such an effect in skin malignancy. Two studies, although limited to small numbers of subjects, were unable to establish a relation between nonmelanoma skin cancer risk and β-carotene intake or β-carotene blood levels.
对应中文
增加类胡萝卜素摄入量的建议是基于一项研究，该研究表明，低摄入富含β-胡萝卜素蔬菜的人患肺癌的风险增加。在血浆β-胡萝卜素水平与肺癌风险以及各种癌症死亡风险之间也证明了类似的负相关关系。此外，对实验动物的研究已经确定，口服β-胡萝卜素可以抑制化学物质和紫外线诱发的皮肤癌。然而，尽管肺癌的流行病学数据支持高β-胡萝卜素摄入可能具有保护作用，但在皮肤恶性肿瘤中缺乏这种作用的证据。两项研究，虽然仅限于少数受试者，但无法确定非黑色素瘤皮肤癌风险与β-胡萝卜素摄入量或β-胡萝卜素血液水平之间的关系。
英文原文
Because carotenoids that do not undergo conversion to vitamin A are also cancer retardants, it is believed that they exert their beneficial effect by mechanisms that do not involve conversion to vitamin A. Indeed, in addition to being the precursor of vitamin A, β-carotene is also an excellent antioxidant and free radical trapping agent. Additional molecules with antioxidant properties include selenium and vitamins A, E, and C. They are able to absorb the energy of unstable, extremely reactive oxygen species and convert them into their ground state. These oxygen species, which include the hydroxyl radical and singlet oxygen, are dangerous in that they can damage cellular DNA, proteins, carbohydrates, and lipids. Free radicals and singlet oxygen can react with DNA, causing mutations that lead to malignancy and contribute to the aging process. Thus carotenoids appear to be beneficial in reducing cancer risk by quenching free radicals before they can cause carcinogenic mutations.
对应中文
由于不转化为维生素A的类胡萝卜素也是抗癌药物，因此可以认为它们发挥有益作用的机制不涉及转化为维生素A。事实上，β-胡萝卜素除了是维生素A的前体外，也是一种很好的抗氧化剂和自由基捕捉剂。其他具有抗氧化性能的分子包括硒和维生素A、E和C。它们能够吸收不稳定的、极端活性氧的能量，并将其转化为基态。这些氧，包括羟基自由基和单线态氧，是危险的，因为它们可以破坏细胞DNA、蛋白质、碳水化合物和脂质。自由基和单线态氧可以与DNA反应，导致突变，导致恶性肿瘤，并促进衰老过程。因此，类胡萝卜素在自由基引起致癌突变之前就将其消灭，从而有助于降低癌症风险。
英文原文
The possibility also exists that the efficacy of the carotenoids as cancer preventive agents may relate to their ability to alter the immune response. There is evidence that β-carotene may enhance host immunologic defenses against tumors. Bendich and Shapiro found that rats on a high β-carotene diet had a greater B- and T-Iymphocyte response to mitogens than controls.Tomita et al. implanted syngeneic tumor cellsinto mice and, on rechallenge with tumor cells, noted decreased tumor growth in those receiving oral carotenoids. β-Carotene did not suppress tumor growth when the mice were rechallenged with a different syngeneic tumor line. Because of the specificity of the carotenoid tumor growth inhibitory effect, these investigators propose that carotenoids stimulate the production of tumorspecific antigens. In humans, there is evidence that oral β-carotene administration increases the peripheral blood levels of CD4+ helper T Iymphocytes and natural killer (NK) cells, providing further evidence that carotenoids may be immune system stimulators.
对应中文
类胡萝卜素作为癌症预防剂的功效可能与它们改变免疫反应的能力有关。有证据表明β-胡萝卜素可能增强宿主对肿瘤的免疫防御。Bendich和Shapiro发现与对照组相比，摄入高剂量β-胡萝卜素的老鼠对有丝分裂原有更强的B和T淋巴细胞反应。Tomita等人将同基因肿瘤细胞植入小鼠体内，再次用肿瘤细胞激发，发现口服类胡萝卜素的小鼠肿瘤生长下降。当β-胡萝卜素不抑制肿瘤生长时，小鼠再次挑战不同的同基因肿瘤系。由于类胡萝卜素抑制肿瘤生长的特异性，这些研究者提出类胡萝卜素刺激肿瘤特异性抗原的产生。在人类中，有证据表明口服β-胡萝卜素可以增加外周血CD4+辅助T淋巴细胞和自然杀伤细胞(NK)的水平，进一步证明类胡萝卜素可能是免疫系统刺激因素。
Retinoids
类维生素A
英文原文
As for β-carotene, there is some epidemiologic evidence that low dietary intake of vitamin A and low blood levels of vitamin A are associated with an increased incidence of tumors of epithelial origin. Foods with a high vitamin A content include egg yolk, butter, and liver. Synthetic retinoids (e.g., isotretinoin, etretinate) were developed because of the toxicity that is seen with the high dose of vitamin A needed to achieve a therapeutic effect.
对应中文
有一些流行病学证据表明，关于β-胡萝卜素，饮食中维生素A摄入量低和血液中维生素A水平低与上皮肿瘤的发病率增加有关。富含维生素A的食物包括蛋黄、黄油和肝脏。合成类维生素A(如异维A酸、阿维A酯)之所以被开发出来，是因为要达到治疗效果，必须是高剂量的维生素A，具有明显的毒性。
英文原文
Experiments in mice show that retinoids prevent the development of chemical and UV light-in-duced skin cancers. The mechanism of retinoid action in tumor inhibition and prevention is not clear.Vitamin A maintains cellular differentiation , and deficiency of vitamin A may lead to squamous metaplasia. Thus it is postulated that retinoids may prevent malignant degeneration by enhancement of normal differentiation. Retinoids are also known to bind to nuclear receptors and may function in a similar manner to steroid hormones in regulating gene (and oncogene) expression. Their anticancer effect may also involve enhancement of the immune response to tumors.
对应中文
一项在老鼠身上进行的实验表明，类维生素A可以预防化学和紫外线诱发的皮肤癌。类维生素A在肿瘤抑制和预防中的作用机制尚不清楚。维生素A维持细胞分化，缺乏维生素A可导致鳞状化生。因此，我们推测类维生素A可能通过增强正常分化来防止恶性变性。类维生素A还被认为与核受体结合，并可能在调节基因(和癌基因)表达方面与类固醇激素的功能相似。它们的抗癌作用可能包括增强对肿瘤的免疫反应。
Selenium
硒
英文原文
Selenium is an essential trace element. Major dietary sources include eats (especially kidney and liver), seafood, whole grains, vegetables, and milk. Many epidemiologic studies have found an inverse relation between seleniumin the diet or plasma and overall cancer death rates.Topical and oral selenium provides protection against UV-induced sunburn, tanning, and skin cancer.Experiments on laboratory mice have shown that approximately three times the normal dietary amount of selenium, delivered either topically or orally, significantly retarded the onset and decreased the incidence of nonmelanoma skin cancers induced by UVB irradiation with no toxicity.Topical L-selenomethionine was also shown to be protective against UV-induced erythema in humans, as measured by an increased minimal erythema dose measured 1 day after application.
对应中文
硒是一种必需的微量元素。主要的饮食来源包括食物(尤其是肾和肝)，海鲜，全谷物，蔬菜和牛奶。多项流行病学研究发现，饮食或血浆中的硒与总体癌症死亡率呈反比关系。外用和口服硒可以保护皮肤，防止紫外线诱导的晒伤，晒黑和皮肤癌。在实验室小鼠身上进行的实验表明，通过外用或口服摄入大约三倍于正常饮食量的硒，可以显著延缓由UVB照射引起的非黑素瘤皮肤癌的发病，降低发病率并且没有毒性。使用第二天测量的最小红斑剂量增加结果表明局部使用L-硒甲硫胺酸对紫外线诱导的人体红斑具有保护作用。
英文原文
The mechanism of selenium’s protective effect in skin cancer, and cancer in general, is not well understood.Selenium is a cofactor that increases the activity of the enzyme glutathione peroxidase,which converts hydrogen peroxideto water. Removal of hydrogen peroxide is essential to living systems because it can generate highly reactive hydroxyl radicals that can attack DNA to cause carcinogenic mutations. Thus, selenium may act similarly to β carotene by preventing a rise in the levels of dam aging free radicals. In addition, selenium may increase the activity or quantity of degradation liver enzyme systems; this would potentially increase the rate of inactivation of certain chemical carcinogens to which an organism may be exposed. Another theory is that high levels of selenium may be toxic to rapidly proliferatingtumor cells.
对应中文
硒对皮肤癌和一般癌症的保护作用机制还不清楚。硒是一种辅助因子，可以增加谷胱甘肽过氧化物酶的活性，将过氧化氢转化为水。清除过氧化氢对生命系统至关重要，因为它可以产生高度活性的羟基自由基，这种自由基可以攻击DNA，导致致癌突变。因此，硒可能与β-胡萝卜素作用相似，因为它阻止老化自由基水平上升。此外，硒可能会增加肝脏降解酶系统的活性或数量；也可能会提高可能接触到有机体的某些化学致癌物的失活率。另一种理论是，高水平的硒可能对快速增殖的肿瘤细胞有毒。
英文原文
Although there is much evidence to support the protective effect of selenium against cancer in general, data specific for skin cancer are sparse. Clark etal.found that the mean plasma selenium level in 240 patients with basal cell and/or squamous cell carcinoma was significantly lower than that of 103 controls. A prospective study to determine the effect of selenium blood levels on nonmelanoma skin cancer risk yielded similar results.The National Cancer Institute is currently supporting a study to determine the prophylactic effect of oral selenium supplementation in patients with a history of nonmelanoma skin cancer.
对应中文
尽管总体上有很多证据支持硒对癌症的保护作用，但针对皮肤癌的具体数据却很少。Clark等人发现240例基底细胞癌和/或鳞状细胞癌患者的平均血浆硒水平明显低于103例对照组。一项确定血硒水平对非黑色素瘤皮肤癌风险影响的前瞻性研究得出了类似的结果。美国国家癌症研究所目前正在支持一项研究，以确定口服硒补充剂对有非黑色素瘤皮肤癌病史的患者的预防作用。
英文原文
Burke recommends selenium supplementation of 100 ug/day, especially during the summer, for every adult and 200 ug/day for those with a history of any type of cancer.
对应中文
Burke建议每个成年人每天补充100 ug的硒，尤其是在夏季，有任何癌症病史的人每天补充200 ug的硒。
英文原文
Selenium toxicity is uncommon even at doses of 1600 ug/day for prolonged periods.Evidence of toxicity includes hair and nail brittleness, rash, nausea, and metallic taste.
对应中文
即使每天1600ug的剂量长时间服用，硒的毒性也不常见。毒性的证据包括头发和指甲脆性，皮疹，反胃和金属味。
Vitamin C
维生素C
英文原文
Just as topical selenium has been studied as a photoprotectant, topical vitamin C has been shown to protect porcine skin from UVB- and UVA- induced phototoxic reactions.Vitamin C acts locallyin the skin as an antioxidant and is depleted by UV irradiation; thus topical vitamin C may act as a broad-spectrum photoprotectant by enhancing local levels of vitamin C.
对应中文
正如外用硒作为一种光保护剂被研究，外用维生素C可以保护猪皮肤免受UVB和UVA引起的光毒性反应已被证明。在皮肤中维生素C作为一种抗氧化剂，在紫外线照射下被消耗；因此，外用维生素C可通过提高局部维生素C水平而起到广谱光保护剂的作用。
MELANOMA
黑色素瘤
英文原文
Numerous in vitro investigations have evaluated the role of dietary factors in the causes of melanoma. Retinol and synthetic retinoids reduce colony formation of human melanoma cells.Melanoma cell growth is inhibited in vitro by vitamins B6, C, D, and E.An in vivo study has shown that increased dietary polyunsaturated lipids decrease the initiation time and accelerate the growth rate of transplanted tumors in mice.
对应中文
许多体外研究已经评估了在黑色素瘤发病中饮食的作用。视黄醇和合成类维生素A减少人类黑色素瘤细胞的群体形成。在体外培养中，维生素B6、C、D和E可以抑制黑色素瘤细胞的生长。一项体内研究表明，增加饮食中的多不饱和脂会降低小鼠移植瘤的起始时间，并加快肿瘤的生长速度。
英文原文
Epidemiologic studies have also addressed the role of dietary factors in the cause of melanoma. For example, Mackie et al. found that the percentage of polyunsaturated fatty acids in the triglycerides of subcutaneous tissue was significantly higher in 100 patients with melanoma than in controls. Controls were also more likely than patients with melanoma to have a low percentage of linoleic acid in the triglycerides of subcutaneous tissue. Their findings have led Mackie and Mackie to suggest that butter be used in moderation rather than vegetable oil and that fish be consumed at least twice weekly.
对应中文
流行病学研究探讨了在黑色素瘤发病中饮食的作用。例如，Mackie等人发现100名黑色素瘤患者皮下组织甘油三酯中多不饱和脂肪酸的百分比明显高于对照组。与黑色素瘤患者相比，对照组患者的皮下组织甘油三酯中亚油酸百分比更低。他们的发现使得Mackie建议适量使用黄油而不是植物油，并且每周至少吃两次鱼。
英文原文
In contrast, Osterlind found that margarine and vegetable oil consumption was similar in 474 patients with melanoma and 926 controls. Furthermore, the risk of melanoma was not greater in those who had a high dietary intake of fatty meat compared with those who had the lowest intake of fatty meat. The study also failed to show any significant difference in the consumption by patients with melanoma versus controls of green vegetables, liver, and other carotene-rich and retinol-rich foods. A small protective effect was found with increasing total alcohol consumption.
对应中文
相比之下，Osterlind发现474名黑色素瘤患者和926名对照组患者的人造黄油和植物油摄入量相似。此外，与脂肪肉摄入量最低的人相比，饮食中脂肪肉摄入量高的人患黑色素瘤的风险并不大。这项研究也没有显示黑色素瘤患者与食用绿色蔬菜、肝脏和其他富含胡萝卜素和视黄醇的食物的对照组有任何显著差异。随着酒精摄入量的增加，这种保护作用也很小。
REFERENCES
1.Rackett SC, Rothe MJ, Grant-Kels JM. Diet and dermatology. The role of dietary manipulation in the prevention and treatment of cutaneous disorders.J Am Acad Dermatol. 1993;29(3):447-461.