Mushrooms and Vitamin D

蘑菇与维生素D

原文网址：http://www.berkeleywellness.com/healthy-eating/nutrition/article/mushrooms-and-vitamin-d

作者：BERKELEY WELLNESS 

Mushrooms are the only vegetarian food that can make vitamin D. Actually, they contain a “pro-vitamin,” or precursor, called ergosterol that is converted into vitamin D when exposed to the sun’s ultraviolet (UV) radia­tion—similar to how your skin synthesizes the vitamin in response to sun exposure. However, commercially cultivated mushrooms are almost always grown indoors in the dark, so they usually have negligible amounts of vitamin D. In contrast, wild mushrooms—notably chanterelles, maitake, and morels—are usually rich in D because they get sun exposure.

蘑菇是唯一能产生维生素D的蔬食。实际上，它们含有称为麦角固醇的“维生素原”或前体，在接触太阳紫外线辐射时，可转化为维生素D——其原理，类似于人体皮肤在受到阳光照射时合成该维生素。然而，商业栽培的蘑菇几乎都种植在阴暗的室内，因此，它们的维生素D含量通常可以忽略不计。相反，野生蘑菇——特别是鸡油菌、灰树花和羊肚菌，由于晒过太阳，一般都富含维生素D。

Since 2009 some commercial growers have produced D-enhanced mushrooms by exposing them briefly to UV lamps, typically after harvesting. They are usually labeled “UV-treated” or “high in vitamin D.” D-enhanced mushrooms contain at least 400 IU of vitamin D per 3-ounce serving and usually cost a little extra. The treatment does not darken the mushrooms or affect other nutrients.

2009年以来，某些商业种植者开始出产维生素D强化的蘑菇，他们通常在收割蘑菇后，用紫外光灯短时间地照一下它们。这些蘑菇，标签上通常印着“紫外光处理”或“富含维生素D”。维生素D强化的蘑菇，每3盎司（译者注：85克）一份的，含有至少400个国际单位的维生素D，通常价格稍高一点。这种处理，不会让蘑菇变黑，也不影响其他营养素。

The form of vitamin D produced in mushrooms is D2, unlike the D3 found in the few animal foods that naturally contain the vitamin; most supplements and fortified foods, such as milk, also contain D3. It used to be thought that D2 was less potent and bioavailable in the body than D3. But more recent research—including a study comparing D2 from mushrooms with D3 from supplements, in Dermato-Endocrinology in 2013—has found that D2 is as effective as D3 in boosting the biologically active form of the vitamin in the body. Vegetarians may prefer D2 because it is not derived from animals (D3 in supple­ments is derived from lanolin in sheep’s wool).

蘑菇中生成的维生素D形式是D2，不同于少数天然含有该维生素的动物食品中发现的D3；大部分补品和强化食品，比如牛奶，也含有D3。过去通常认为，来自蘑菇的D2，在人体内的效力和利用度不如D3。但最近的研究——其中有一项研究2013年发表于《皮肤-内分泌学》杂志，比较了来自蘑菇的D2和来自补品的D3——已发现，在增强人体内该维生素的生物活性形式上，D2和D3一样有效。素食者可能会更喜欢D2，因为它不是来自动物（补品中的D3，源于羊毛中的羊毛脂）。

Increase the vitamin D in your mushrooms

提高蘑菇中的维生素D

Over the past decade, scientists have found that it takes only a modest amount of UV from the sun or special lamps to produce significant levels of vitamin D in mushrooms. Just 15 minutes of direct sun­light can produce 200 to 800 IU in 3 ounces of mushrooms (the daily RDA is 600 to 800 IU), regardless of type or season. At least 90 per­cent of the vitamin is retained after storage and cooking. Whole button mushrooms synthesize the least D; sliced buttons, however, are proficient D producers. If you do this your­self, place the mushrooms with the “gills” (also called lamellae, under the caps) facing the sun to increase D production. The mush­rooms may discolor or dry out a little.

过去10年，科学家已发现，只要用来自太阳或特殊灯具的紫外线稍微照射一下，蘑菇中就能产生大量的维生素D。15分钟的直射阳光，就会让3盎司蘑菇生成200到800国际单位（每日需求量是600到800单位）的维生素D，无论是什么品种或季节。在存放和烹饪后，至少有90%的维生素D能得以保留。完好的草菇合成的维生素D最少；不过，切成片的草菇，是产维生素D的高手。如果你亲自动手，请将蘑菇的“鳃”（也称菌褶，伞盖下面的部分）朝向太阳来提高维生素D的产量。蘑菇可能会有点变色，或者发干。