Nutrition 101
I am sure that this isn't the first time anyone tells you that a healthy diet equals a healthy you. You might be thinking that diet will not reverse the age factor and no matter how healthy you eat, you will finish by getting many diseases as you age. I am glad to tell you that you are WRONG!!! :)
It's true that diabetes, high blood pressure, etc...are usually not inherited and get pronounced later on in life, but this is certainly not due to age.It's usually the result of long-term bad eating habits.
On the other hand, some changes in the normal body conditions, such as in pregnancy, require a modification in the diet.
And lastly, if you are  physically active you should adjust your food intake accordingly.

So, in the following sections, I am basically going to tell you what these changes should be. But first, I will give you a brief overview of food constituents to make you understand the concepts that lie behind these dietary modifications. So to give you a better understanding, I would like you to observe these two diagrams and try to find similarities between them.

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So, were you able to find similarities between the two charts? Are you wondering what the second chart presents? I am pretty sure you are, well I am here to explain all these complicated terminologies to you.
I am pretty sure that you are already familiar with the first, it basically represents what we were talking about in the first section (proportion of number of servings required from each food group). The second one might seem problematic and complex. But it is not, it just translates your food requirements from common language to your body's language and it basically represents how much from your food intake should come from the different kinds of nutrients.

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You're probably thinking: Oh well, I am a healthy adult so I do not need growth or repair, I am going to stick with eating fruits, vegetables and grains, after all that's all my body needs: ENERGY! BUT THAT'S NOT TRUE!!!! Your body is in constant growth and repair, but this happens on the inside and you can't really see it. So it is very important that you eat from the different kinds of nutrients in the appropriate proportion to meet your body needs.
Some other components called vitamins and minerals, are essential for the body's maintenance and functioning. There are many kinds of vitamins and minerals and different food items contain different combination of them.