References:

Plants and Society; Pages 160-176

On Food and Cooking; Pages 517-552

http://www.cc.nih.gov/ccc/supplements/intro.html

Macronutrients:

Carbohydrates

monosaccharide-glucose
disaccharide-sucrose
polysaccharide-starch (complex carbohydrate)

Proteins

essential amino acids (ones we cannot make)
nonessential amino acids (ones we can make)

Fats

essential fatty acids
saturated fatty acids

hydrogenation (trans fatty acids)

unsaturated fatty acids
cholesterol

Micronutrients:

Vitamins

Fat soluble: (A,D, E, K)
Water soluble: (B₁-Thiamine, B₂-Riboflavin, Niacin, B₆, Pantothenic acid, Folic Acid, Biotin, B₁₂, C)

Minerals

Major Minerals (Ca, K, S, P, Cl, Na, Mg)
Trace minerals (Fe, Zn, I, F, Cu, Se, Co, Cr, Mn, Mo)

MACRONUTRIENTS are molecules that we need in very large amounts. We need the carbohydrate glucose as the energy source for our cells. Glucose can be eaten as glucose, but most often we eat glucose as sucrose (table sugar) or starch (complex carbohydrate). Lipids (fatty acids and cholesterol) are needed to build membranes and proteins form major structural components of cells as well as functioning as enzymes.

We eat proteins to gain amino acids. There are 20 amino acids that we must have in order to make proteins in our cells. We can make 11 of those amino acids, and the amino acids that we can make are called NONESSENTIAL AMINO ACIDS. The 9 amino acids that we cannot make are ESSENTIAL AMINO ACIDS. It is important to consume "complete protein". Protein from animals is usually complete, whereas protein from plants is often lacking one or more essential amino acids. However one can mix plant foods to get complete protein. For example, beans are low in methionine but have enough tryptophan and lysine. Corn is low in tryptophan and lysine, but adequate in methionine. Thus beans and corn provide complete protein.

There are also fatty acids that we cannot synthesize, but need anyways, and these fatty acids are ESSENTIAL FATTY ACIDS. Deficiencies in essential fatty acids are rare, but have occurred in infants fed a formula.

The difference between saturated and unsaturated fatty acids is given more consideration in modern nutrition. Plants contain a mixture of both saturated and unsaturated fatty acids. Unsaturated fatty acids can be monounsaturated (olive oil, peanut oil, canola oil), having only on C=C bond or polyunsaturated (corn oil and palm oil), containing several C=C bonds.

Food producers convert unsaturated fatty acids from plants into saturated fatty acids, called TRANS FATTY ACIDS, by bubbling hydrogen through the fatty acid (a process called HYDROGENATION).

The other type of lipid that we require in large amounts is steroids, particularly cholesterol. Cholesterol is a major component of eukaryotic cell membranes. We must consume and process a large amount of cholesterol to remain alive. Cholesterol is transported throughout our bodies in clumps of cholesterol surrounded by a protein lipid layer to form a structure called a LIPOPROTEIN. There are two main types of lipoproteins that transport cholesterol in our blood, low density lipoproteins, LDLs, that transport cholesterol to all or our cells (as all of our cells nee cholesterol) and high density lipoproteins, HDLs, that transport cholesterol to the liver for degradation and elimination. We generally consider HDLs to be "good" because they remove excess cholesterol and LDLs to be "bad", because they can cause buildups of cholesterol in our arteries, although that buildup is often if not always caused by some other factor, like an infection or genetic defect.

While the principle nutrient we need is glucose, as it is the basic energy source for our cells, we need a variety of other nutrients as well. Traditionally, we would eat fruits, vegetables and meats, all of which contain a variety of nutrients, including sugar. However, we often find ourselves consuming "empty calories" today (sugar only, or perhaps starch only) in forms such as candy bars. These calories are "empty" because the food source lacks the other nutrients we need to stay alive.

The other nutrients, MICRONUTRIENTS, we will discuss today are VITAMINS and MINERALS. Vitamins are small organic molecules needed as parts of certain types of chemical reactions in the cell. Minerals are inorganic elements needed for the same reason. Deficiencies of micronutrients lead to particular sets of symptoms.

Vitamins are of two types, fat soluble and water soluble. It is important to be aware of those that are fat soluble, as they can build up in the fatty tissues and cause disease of death. Water soluble vitamins are passed though the body, and are usually not toxic unless taken is exceptionally large amounts. Our textbooks review the effects of various vitamin deficiencies, and I will expect that you know any 2 of them. Scurvy, for example, is caused by vitamin C deficiency. Vitamin C is ASCORBIC ACID, which is used by cells that make COLLAGEN. Collagen is the most abundant protein in the body, and is often secreted and forms connective tissues like cartilage. Collagen is the major part of the "glue" that holds cells together. Vitamin C deficiency causes bleeding of the gums, hemorrhaging under the skin, fatigue, failure of wounds to heal, brittle bones, and can lead to massive internal bleeding.

Niacin deficiency causes a disease called PELLAGRA, once very common in this region as corn was once a dietary staple, and corn contains niacin in a form that we cannot use, and is low in the amino acid tryptophan, from which we can make niacin. Pellagra affects the central nervous system, causing dizziness, hallucinations. Pellagra also affects the gastrointestinal system, causing abdominal pain and vomiting. Niacin is what we call NAD+ and NADP+. If you can recall from earlier lectures, these two small organic molecules play a central role in primary energy processing in the cell, and energy release from cells is restricted when niacin is deficient, with cells having high energy requirements being the first and most affected.

Minerals are divided into major and minor minerals. The major minerals are those we needing large amounts and the minor ones are those we need in small amounts. We must have acceptable levels of all of these minerals for our cells to function, and deficiencies of minerals lead to diseases just like deficiencies of vitamins. Calcium, for example, is a principle components of bone as well as a major signal molecule in cells like muscle cells. Calcium deficiencies cause OSTEOPOROSIS, weak "porous" bones. Vitamin D is needed for the efficient absorption of calcium, and thus vitamin D deficiency can also lead to osteoporosis by causing low absorption of calcium, even though you take in more than you need.

I will expect you to know at least the effects of deficiencies in at least 2 minerals.

Finally, "On Food and Cooking" spends a lot of time discussing nutritional fads. Ever since it was discovered that we have specific nutritional needs, and that many diseases are in fact caused by nutrient deficiencies, we have had nutritional fads. The oldest one discussed in "On Food and Cooking" is the Salisbury Steak. The inventor, a Dr. James Salisbury, decided that many ailments were caused by starchy foods. In his wisdom, he decided that humans were 2/3 carnivorous and 1/3 herbivorous (probably the opposite of what we really are!), and thus we must increase our intake of more or less pure protein. So he designed the "Salisbury Steak", which was lean meat with the connective tissue ("glue") removed. Salisbury believed that starch "ferments" in our digestive system causing a wide variety of ailments. Salisbury also advised drinking lots of hot water to flush the products of fermentation out of the digestive system. Interesting to note that modern Salisbury Steaks contain little lean meat, and a lot of "glue"!

Of course, there were opposing views, not the least of which was that of Dr. John Harvey Kellogg, who advised a vegetarian diet, as he believed that among other things, meats contained the waste products of the animals last muscular activity, and that these products were harmful toxic substances that should be avoided.

Today, vitamin E is promoted as an "antioxidant" despite the lack of clinical evidence that vitamin E makes any difference at all. We do know, however, that vitamin E does participate in biochemical reactions (along with vitamin C) that remove "free radicals" from our cells. We have, however, metabolic machinery for removing free radicals from cells, and while vitamin E will remove free radicals, the question really is "does vitamin E in our actual living cells increase the rate of free radical removal in a manner that improves health"?