It's one of the most recognizable expressions around: "An apple a day keeps the doctor away." But besides the fact that it rhymes, which makes it fun to say and easy to recall, does it really have any value? Could the common apple honestly help a person to maintain perfect health?

The first printed mention of this saying can be found in the February 1866 issue of the publication "Notes and Queries." The publication printed the proverb like this: "Eat an apple on going to bed, and you'll keep the doctor from earning his bread." Nearly 150 years later, variations of this adage are still quoted. It's unlikely that the saying would have maintained such popularity if there wasn't some truth to it, right? With that in mind, let's consider some of the apple's components and their effect on our health:

*Pectin -- Pectin is a form of soluble fiber than lowers both blood pressure and glucose levels. It can also lower the levels of LDL, or "bad" cholesterol in the body. Pectin, like other forms of fiber, helps maintain the health of the digestive system. Apples are an excellent source of pectin.

*Boron -- A nutrient found in abundance in apples, boron supports strong bones and a healthy brain.

*Quercetin -- A flavonoid, this nutrient shows promise for reducing the risk of various cancers, including cancers in the lungs and breast. It may also reduce free radical damage. Free radicals develop when atoms in the body's cells have unpaired electrons, which can lead to damage to different parts of the cell, including DNA. Quercetin may neutralize free radical damage, which has been implicated in a variety of age-related health problems, including Alzheimer's disease.

*Vitamin C -- Vitamin C boosts immunity, which helps maintain overall health.

*Phytonutrients -- Apples are rich in a variety of phytonutrients, including vitamins A and E and beta carotene. These compounds fight damage from free radicals and can have a profound affect on health, including reducing the risk of heart disease, diabetes and asthma.

Apples also act as a toothbrush, cleaning teeth and killing bacteria in the mouth, which may reduce the risk of tooth decay. They're also low in calorie density, one of the trademarks of a healthy food. When a food is low in calorie density you can eat good size portions of the food for relatively few calories. In addition, apples are affordable and readily available.

With all of this information, it's easy to see that, yes, an apple has its health benefits. But does eating an apple every day mean you'll never get sick? And is an apple really healthier than other fruits? Find out on the following page.

"一天一个苹果医生不来找我"这是人人皆知的顺口溜之一。但事实上它只是童谣而已，便于好说好记，它真的有什么价值吗？一个再普通不过的苹果真的能帮助人保持完美健康？

出版刊物"备忘和查询"（Notes and Queries）1866年2月号中首先发现有对它的叙述。出版刊物中有谚语："睡前吃一个苹果，医生就会丢饭碗。"差不多在150年之后，这个变化了的谚语一直被引用。如果说的没有一点事实，它也不可能一直被传说和流行。它让我们考虑苹果的成分及其对我们健康的作用：

果胶--果胶是一种可溶纤维能降低血压和葡萄糖水平。它还能降低身体LDL（低密度脂蛋白）或"坏"的胆固醇水平，像其它纤维素一样，能帮助消化系统维持健康状态。苹果是果胶的极好来源。

硼--在苹果中发现的一种丰富营养素，硼能壮骨和健脑。

槲黄素--一种类黄酮，这种营养素表明能降低包括肺癌和乳腺癌在内的各种癌症的危险。它还能减轻自由基破坏。自由基发生是当身体细胞中的原子有单电子，能导致包括DNA在内的细胞不同部分的破坏。槲黄素能中和自由基损害，包括老年痴呆症在内的各种老化相关的健康问题。

维生素C--维生素C能提高免疫性，帮助维护整体健康。

植物营养素--苹果含有丰富的包括维生素A 和 E在内的各种植物营养素及贝它胡萝卜素。这些成分可以战胜自由基破坏并对健康有深奥影响，涉及减少心脏病、糖尿病和哮喘的危险。

苹果还有牙刷作用，洁齿和杀灭口腔细菌，减少龋齿的危险。它们还能降低卡路里，这是保健食品的商标标志之一。当食品卡路里低，你就能吃相对低卡路里的大量食物。另外苹果还是廉价和容易得到的。

显而易见所有这些信息，是说苹果具有健康效益。但每天吃一个苹果就意味着绝不会再有危险了？吃一个苹果真的就比其它水果更健康？