Stuff We Eat
They tell you some foods will make you fat, some will make you thin, some are "superfoods", and some will kill you. Here we take a quick fact-based tour of everything that you actually eat.
Few subjects are as full of pseudoscience as food. It seems just about every food is either being promoted as health food, or condemned as junk food. In fact, everything we eat breaks down into the same seven basic categories.
First are amino acids. These are what make up proteins. There are many different amino acids. There are eight that we need, and a few dozen more that are really useful. Our bodies break down all the proteins we eat into these amino acids, to use as building blocks to construct whatever compound it needs.
Second are fatty acids. Most of this is fat that we don't need, with the exception of omega-3 and omega-6 fatty acids, which we must eat. All other fatty acids get broken down and stored as fat, or used as more building blocks.
Third are carbohydrates. Basically, sugars. There are five single sugar molecules such as glucose and fructose, called monosaccharides. Every carbohydrate, whether it's bread or sugar, consists of multiple saccharides, like disaccharides and polysaccharides. Your body always breaks these down into the five basic monosaccharides, to use as building blocks.
Fourth are vitamins. What is a vitamin, anyway? It's any organic compound that your body can't synthesize from those other building blocks, and that you have to get from food. The amount of these that you need is quite small; any normal diet provides more than enough of all of them for most people. With very few exceptions, taking a vitamin supplement is like pouring water into a bucket that's already overflowing.
Fifth are minerals. Literally minerals, like iron and calcium. There are about sixteen essential minerals that your body needs.
Sixth is water. Just about everything you eat or drink contains some water, and your body needs that most of all.
Seventh is everything else - things that your body does not break down and does not use. If you swallow a glass marble or a piece of gravel, it passes right through your system. A lot of foods and some additives contain random things that your body doesn't absorb.
Any food, Twinkies or soy beans, can be part of a healthy diet, or part of an unhealthy diet. It all depends on how much of them you eat. All foods consist of these same basic bits, just in different proportions. A decent balanced diet is all you need; there's no reason to spend money on anything else.
References & Further Reading
ADA. "Position of the American Dietetic Association: Nutrient Supplementation." Journal of the American Dietetic Association. 1 Dec. 2009, Volume 109, Issue 12: 2073-2085.
Chiras, D. Human Biology. Sudbury: Jones & Bartlett Publishers, 2005. 81-92.
Holick, M. "Vitamin D Deficiency." New England Journal of Medicine. 19 Jul. 2007, Volume 357, Number 3: 266-281.
Kennedo, G. "Dietary Reference Intakes Tables and Application." Institute of Medicine. National Academies of Sciences, 14 Jan. 2010. Web. 25 Jul. 2010. <http://www.iom.edu/Activities/Nutrition/SummaryDRIs/DRI-Tables.aspx>
Simopoulos, A., Cleland, L. Omega-6/omega-3 essential fatty acid ratio: the scientific evidence. Basel: S. Karger AG, 2003.
USDA. "USDA Nutrition Evidence Library, 2010." Nutrition Evidence Library. USDA Center for Nutrition Policy and Promotion, 15 Jun. 2010. Web. 26 Jul. 2010. <http://www.nutritionevidencelibrary.com/default.cfm?>
USDA. "Questions To Ask Before Taking Vitamin and Mineral Supplements." Nutrition.gov. USDA National Agricultural Library, 11 Jun. 2009. Web. 7 Jul. 2010. <http://www.nutrition.gov/nal_display/index.php?info_center=11&tax_level=2&topic_id=1939>