视频文本

Another macro-mineral is magnesium which can be found in our bones.
另一种常量元素是镁，也存在于我们的骨骼中
The nervous system uses magnesium to transmit signals in nerves throughout our body.
神经系统利用镁在全身的神经中传递信号，
Proteins are made by enzymes that require magnesium to function properly.
蛋白质由酶制造，而酶需要镁才能正常工作
Good sources of this mineral include nuts,
富含镁的食物包括坚果
legumes, whole-grained cereals, and leafy green vegetables.
豆类，全粒谷物以及绿叶蔬菜
The recommended daily allowance, or RDA, is 700 mg for people over the age of 19.
对19岁以上的人建议每日摄取量(RDA)为700mg
Supplementation of magnesium is usually not necessary
通常不需要另外补充镁
because of the abundance in foods
因为食物中富含镁，
and toxicity can result from over-consumption of supplemental magnesium.
而且过度补充镁摄取会导致中毒

Potassium is a very important electrolyte in our body.
钾是人体中重要的电解质
The electrolyte minerals include potassium, sodium and chloride.
电解质矿物质包括钾，钠和氯化物，
These minerals insure adequate balance of electrical charge and water concentration around the cells of the body.
这些矿物质保证了人体细胞周围的电荷和水浓度平衡
Most diets contain adequate amounts of these minerals and deficiencies rarely occur.
大部分人的饮食中都包含足够的这些矿物质，很少出现缺乏
Potassium is important for muscle contraction
钾对于肌肉收缩很重要。
and may become low in the elderly or with the use of certain medications.
随着年龄增长或者使用某些药物钾在体内
Potassium is found in avocados, bananas, potatoes and dairy products.
含量会降低，鳄梨，香蕉，土豆和奶制品富含钾，
There is no defined RDA for potassium.
对于钾没有确定的RDA
Sodium is another electrolyte.
钠也是一种电解质
The media gives most of its attention to the adverse health effects of over-consumption of this mineral,
媒体大都关注过度摄取钠对健康的不利影响
usually in the form of table salt.
大部分钠通过食盐被摄取
Sodium is an important mineral in our bodies because of its role in water, pH and electrolyte regulation.
钠是人体内的重要矿物质，因为它对于水酸碱度和电解质的调节有重要作用
Besides table salt almost all foods contain sodium.
除了食盐，几乎所有食物都含钠
However, salt added to processed foods is the primary source of dietary sodium.
但是食物加工过程中加入的盐是饮食中钠的最主要来源，
In general the average American diet provides high amounts of sodium.
总的来说美国人的饮食中含钠量很高，
The upper level intake for sodium is 2300 mg per day.
每天摄取钠的上限是2300mg
It is easy to consume well above that amount in a single meal,
但是一顿饭就很可能摄取超过2300mg的钠，
especially fast foods, restaurant meals and processed foods.
尤其是吃快餐，在餐馆吃饭或者吃加工食品时

视频及简介

视频简介：

本节课介绍矿物质（无机盐），依次讲了钙、镁、钾、钠、铁、铜、锌和硒的作用、缺乏带来的影响、以及如何从食物中获取足够的矿物质。