How we take care of our bodies relies in large part by what foods, nutrients,vitamins or supplements we put in. Of course equally valuable to be concerned about depending on our lifestyle must be to recognize our unhealthy intake habits, like alcohol, caffeine,fried foods, nicotine and tobacco, excess use of over the counter drugsand purely fattening foods and useless calories. Being aware of the unhealthy choices we practice is the first step at being able to augment unhealthy choices with foods or supplements that can reduce (not distinguish) the unhealthy aspects of those too. Thus giving your health at least a better chance to rejuvenate and perhaps in your future would allow for healthier habits.
I suggest that it is quite useful to obtain a few good books on such matters which you could refer with at your discretion and needs. Having useful information at hand in your possession can do wonders for the moments when you have a question. Good books to look for are out there in the world; stores, libraries, resource centers, and internet. A book about vitamin, mineral, nutrient supplements such as Dr. Earl Mindell's Vitamin Bible and others which can give an overview of what certain vitamins actually do and what exact foods contain them; there are many out there to choose from. A good food diet book overview is also good to have that explains what nutrients come from which foods and in what amounts as well as calorie counting for each foods. For example Beta Carotene (Pro-Vitamin A) is a non-toxic way to get your vitamin A where as vitamin A oils can be toxic in larger quantities because it is not water soluble. Vitamin B1 (thiamine) is an antioxidant that can help the liver detoxify your body and works in conjunction with vitamin C (ascorbic acid) which also boosts the livers function.
How much fiber is enough? How fast do you personally burn the particular kind of calories you are eating? How do different kind of complete and incomplete proteins breakdown and revitalize your tissues? What really are amino acids related to protein? Which is more dangerous to you, the tar in your lungs or the nicotine you inhale?
Those seemingly hard to pronounce words on over the counter labels are not as difficult as they seem when you find a good guidance book or reference. What exactly is the negative problems with cholesterol and arteries? Did you know that cholesterol in some ways is necessary? Did you know vitamin C is destroyed by heat as well as other vitamins? Did you know light causes oils and nuts to go rancid making them more harm than good? Why is the relationship between salt and potassium important? Did you know that oranges are far from being the best source of vitamin C (even tomatoes and other vegetables and foods contain vitamin C.)
To sum up for now it is very worth it to yourself and those you know to find some good references you can always have at hand. Written by scientists and a good exploratory work is Life Extension: A Practical Scientific Approach which is interesting if you want to explore more about supplements. There are good books about Hypoglycemia, Diabetes, Heart Disease, and about ANYTHING you could think up. Remember to never believe anything just because it is in print. Always cross reference and read from a few different sources and viewpoints. Also a few other references worth a look (it is always good to be reminded even of the facts we may already know): http://canadafoodguide.ca , http://healthcheck.org ,
How Stuff Works;vitamins. http://concerninghealth.webs.com

Author's Bio: 

G.Thomas was educated at the University of Toronto and has experienced involvement in many belief system practices throughout the years. He has worked as an English Tutor and Counselor. He has experience working in the Health Food Retail industry and has read extensively about nutritional supplements and diet. G.Thomas is well versed in practical philosophies and writings. He has had experience in studying metaphysics, epistemology, objectivism, Christianity, Scientology, Zen Buddhism, Atheism, Montessori Method of schooling, 12-Step Programs, Addiction Rehabilitation, Martial Arts and Constructive Living (D.K.Reynolds.) His sociological study continues and the website Grasping Thoughts is concerned with Mindful Self Improvement Practices and Beliefs. He presently resides in Ontario,Canada and continues with writing pursuits and sociological studies. Have a quick read if you will; many like my site. Regards, G.Thomas