"You are what you eat". This is basically true although, if you eat an apple, you are safe about not having little bits of apple roaming about your body. A good way to look at it is that what you eat provides building blocks for your body to use -- both keeping the body at operating temperature as well as to replace old cells and build new ones. The system of doing this is called metabolism and it is not really well understood although there is a new theory (and a new diet) on a regular basis.
Most of the nutritional studies are of an experimental kind. This doesn't usually mean a room full of lab rats (although such may be involved). It means that the people examine what goes in and then monitor effects that can be measured. The "in-between" mechanisms are still rather mysterious -- but there are some fascinating studies that have been published in the last few years about the symbiotic roles of bacteria, viruses, and other "critters" that exist on our skin, within our digestive track and even within our cells and organs. The mitochondria, that exist within all of our cells and are an integral part of metabolism, probably originated as one of the first symbiotic organisms.
One thing to be very careful about when considering nutrition is that the food brought in is broken down and then reused (building blocks, remember). If a person eats cholesterol (a fat with a bad reputation), it does NOT get directly rerouted to the arteries. You can eat all the protein you want and, without doing other things, it will not automatically give you huge muscles.
We mentioned in the previous blog that nutrition is involved with the availability of various components in the diet -- including fats, proteins, carbohydrates, minerals, vitamins, and dietary fiber (actually, soluble dietary fiber). This blog will focus on fat which probably has the worst Public Relations system of all.
It would probably help the reputation of fat if there were two words for different situations. Call the fat that you consume "oils" and the fat that you possibly have in excess around your middle as "reserve materials". Fat is very important in our diets and our bodies cannot produce healthy cells without it.
Oils are organic solvents. This means that organic materials tend to be able to dissolve in, and disperse within, fats or oils. This is why fat added to cooking aids the flavor significantly. Spices and other materials that cause us to say "yummy" are dispersed within the fat. This same property is necessary within our metabolism -- the fats provide a "kettle" that can be used to concoct all kinds of cells. One important class of cells that requires fat is our nervous system. A lack of sufficient fat in the diet can cause nerve damage and is why pediatricians emphasize to NOT give fat-free milk to infants -- they need the fat to help produce healthy brains and a healthy nervous system and do not have other sources for the fat.
There is rarely a consensus (everyone agreeing) within the nutrition field but, in general, it is recommended that about 25% of the calories we consume come from fats. Since fats have a bit more than twice the calories per unit as proteins and carbohydrates, this means about 12% of our food, by weight, should be fats. Excess fat, by itself, will not directly lead to greater "reserve materials" around the waist.
Our bodies are very wise and they know what we need. We are designed as omnivores -- so the easiest way that our bodies can grab all the needed building blocks from our diet is to eat a good assortment of foods, including meat, vegetables, and grains. Vegetarians, and vegans, can also have a very healthy diet (some say more healthy) but the body alone can not grab all the needed building blocks without some careful planning of our diets -- the building blocks that come from meat (in particular, a balance of "essential" amino acids) must be replaced by equivalent building blocks from other foods. If we get all we need, the excess will be removed from our bodies. However, if we get an excess of calories (and have the base foundation nutrition that we need), the body probably WILL make use of some of the building blocks to put down a layer of those "reserve materials".
The area of greatest controversy and the fastest shifting arena within nutrition is the battle of "good fats" and "bad fats". Once upon a time, people were encouraged to eat margarine and avoid all the "bad fats" of butter which comes from animals ("moo"). Currently, butter is considered to be better than margarine because, in the process of making margarine solid, it creates certain "bad fats" known as Trans-fats. Butter also has trans-fats but less than most solid margarine and more "natural" since it was created by an animal. There are saturated fats, unsaturated fats, polyunsaturated fats, monosaturated fats, Omega-3 fats, and so forth. If you want to know more about these, there are lots of good books about various fats out there. Right now, the general idea is that the less saturated that the fat is the better it is for you.
So, what is the best fat for you? This is where economics rears its head again. A person can get oils from fruits (olives), vegetables (sunflowers), legumes (peanuts), grains (rapeseed -- canola), and animals (lard as well as Omega-3 oils). Many recipes and references just split these oils into vegetable oils and animal fats.
Canola oil is produced heavily and is, therefore, one of the cheapest oils but there is some controversy over its genetic history. Omega-3 oils are in much smaller supply and are, therefore, one of the more expensive oils. Since this area is most in flux, I certainly won't try to recommend a specific oil but, if you look into the pantry of people, the type(s) of oils you find will certainly reflect income level to a considerable degree -- and some say the more expensive oils are "better".
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