Fat

Fat

Principle lipid storage molecule in many organisms.

More strictly, triglycerides may be differentiated into fats versus oils, which differ in terms of their relative melting points. Thus, fats tend to melt at higher temperatures than oils, resulting in the latter being liquid particularly at room temperatures. This distinction, however, makes little difference in terms of the total Calories associated with triglycerides and when one speaks of dietary fats usually both types of triglycerides are included. The primary storage tissue for fats in our bodies is adipose tissue.

Links to terms of possible interest: Fat, Fatty acid, Glycerol, Oil, Triglyceride

The above video is a fairly good introduction to fats and other lipids.

The above video is another fairly good introduction to fats and other lipids.

The above video provides a very short overview of fat digestion.

The above video considers the digestion of fats with lots of emphasis on bile salts and provides a fair amount of detail.

Triglycerides

Biomolecule generated via covalent bonding between glycerol and three fatty acids.

In physiology, the concept of triglycerides has more than one level of meaning. Biochemically, a triglyceride is simply a fat, that is a lipid consisting of the molecule, glycerol, and three fatty acids. Fats, so defined, are the principle long-term energy storage molecules of the body, i.e., triglycerides that are stored as fat droplets within adipose tissue. Alternatively, there is the presence of triglycerides in the blood. Chemically, blood triglycerides are no different from those already found within adipose tissues, but at the same time blood triglycerides provide a different physiological marker than do triglycerides that are already found in storage within adipose tissue. Thus, blood triglyceride levels are routinely determined, along with that of LDLs and HDLs, with higher levels considered to be a potential precursor for cardiovascular disease. In particular, it is diets that are high in more-refined (less "complex") carbohydrates, e.g., sugars but also refined starches, that appear to be especially associated with higher levels of blood triglycerides.

The above video provides a quick rundown on some of the things that you can do to reduce levels of blood triglyceride levels.

The above video can get a little confusing when trying to represent how the "octet" rule is satisfied between carbon atoms (trust me, it is confusing), but nonetheless provides a pretty good explanation of what triglycerides represent as well as why it makes sense that they can store large amounts of energy; consider starting at 3:59 in order to avoid much of the preliminary discussion that basically is an introduction to the "octet" rule; the video also doesn't do a very good job of describing ester linkages, but it also doesn't dwell on the ester linkages, i.e., as found between fatty acid and glycerol moieties, so we won't worry about this either.

Fatty acid

Long-chain carboxylic acid.

Triglycerides consist of the molecule, glycerol, to which three fatty acids have been bonded. The fatty acids, in their long carbon and hydrogen chains, are both quite hydrophobic and store substantial amounts of energy, just as fossil fuels such as petroleum oil or natural gas also store large amounts of energy. The absorption of fats from the small intestine involves first their cleavage, via the action of lipases, into the molecule glycerol plus fatty acids. Note that some fat digestion actually begins in the mouth via the action of what is known as lingual lipase, which is associated with saliva. The fatty acids are able to directly cross the mucosa without protein facilitation. Those with shorter chains enter directly into the blood. Those with longer chains, by contrast, are reassembled into triglycerides within mucosal cells and then packaged within proteins to form what are known as chylomicrons. Chylomicrons then enter into the lacteals of villi, and thereby initially travel within lymph before entering the blood. Fatty acids are also generated by adipocytes (fat cells) in the process of the catabolism of stored fat. The differentiation among fats into saturated fats, unsaturated fats, polyunsaturated fats, monounsaturated fats, and trans unsaturated fats all are in terms of the characteristics of the fatty acid moieties that, in addition to glycerol, make up a given fat.

Saturated fats

Triglycerides consisting of fatty acids that lack double bonds and therefore which tend to be solid at room temperature.

A saturated fat is a triglyceride that is made up of fully saturated fatty acids. These fatty acids completely lack carbon-to-carbon double bonds and thus possess as many carbon-to-hydrogen bonds as is possible. That is, saturated fatty acids literally are saturated with hydrogen atoms as they cannot hold any more hydrogens than they already do. Generally saturated fats are not considered to be as healthy to consume as unsaturated fats, though they are preferable to trans fats (which are a type of synthetic, that is, artificial unsaturated fat). Saturated fats don't need to be avoided entirely in a diet though should be consumed in relative moderation. In particular, saturated fats are associated with warm-blooded animals, especially mammals (e.g., cows or pigs), but also tropical fruits and nuts such as coconut oil and palm oil. It is when you are consuming these things, including the fatty parts of meats from these animals as well as many processed meat products, that you are consuming relatively large quantities of saturated fats.

The above video provides a comparison between saturated fatty acids and unsaturated fatty acids as well as cis unsaturated fatty acids versus trans unsaturated fatty acids, concentrating on the chemistry rather than physiological effects (though they mention physiology as well in terms of trans fats).

Unsaturated fats

Triglycerides consisting of fatty acids that possess double bonds and therefore which tend to be liquid at room temperature.

The unsaturation that makes an unsaturated fatty acid an unsaturated fatty acid and therefore makes an unsaturated fat an unsaturated fat comes in two types, one natural and one artificial. The natural type of unsaturation is known as a cis double bond versus the artificial unsaturation that is known instead as a trans double bond. Unsaturated fats can be further distinguished in terms of how many unsaturations they possess as well as the locations of their double bonds. Fatty acids that possess only a single carbon-to-carbon double bond are described as monounsaturated versus polyunsaturated, which refers instead to the possession of more than one carbon-to-carbon double bond.

Polyunsaturated fats

Triglycerides consisting of fatty acids that possess multiple double bonds and therefore which tend to be liquid at room as well as lower temperatures.

Think, for example, of corn oil… Among polyunsaturated fatty acids are so-called omega-3 fatty acids and omega-6 fatty acids, which differ in the location of the first double bond counting from the end of the fatty acid carbon chain (that carbon, that is, which is bound to three hydrogens but to only one carbon atom). Both omega-3 fatty acids and omega-6 fatty acids are considered to be essential since our bodies cannot synthesize them and these fatty acids are otherwise necessary for health.

Monounsaturated fats

Triglycerides consisting of fatty acids that possess single double bonds and therefore which tend to be liquid at room but not lower temperatures.

Think, for example, of olive oil… Health-wise, monounsaturated fats appear to be preferable to saturated fats and may also be preferable to polyunsaturated fats, though the verdict on the latter claim is less robust. Monounsaturated fats, particularly in the form of olive oil, is a feature of the so-called Mediterranean diet, which appears to be cardiovascularly healthful despite tending to also be relatively high in fat as a total number of Calories. The Mediterranean diet is also high in plant-based foods, high in omega-3 unsaturated fats, and low in saturated fats.

Links to terms of possible interest: Double bond, Fat, Fatty acid, Hydrocarbon, Monounsaturated fat, Monounsaturated fatty acid, Omega-3 fatty acid, Omega-6 fatty acid, Polyunsaturated fat, Polyunsaturated fatty acid, Saturated fat, Saturated fatty acid

Trans fats

Triglycerides consisting of fatty acids that possess unnaturally oriented double bonds.

Trans fats are a consequence of technology run amok along with the concept that a little bit of information can be dangerous (all in combination with greed, marketing, and just plain stupidity). Trans fats came about as a side product to a poor solution to problems that only arguably existed. The first problem was one of excess saturated fats in the diet. The solution was to replace these fats with unsaturated fats. The unsaturated fats didn't work as well technologically, however, in terms of the texture of various commercially available processed foods (think margarine). This second problem was solved, believe it or not, by taking unsaturated fats and making those fats less unsaturated, that is, more saturated. Saturating hydrogens were added back to unsaturated fats so that in effect a compromise between saturated fats and unsaturated fats could be reached, one that was still technically (sort of) unsaturated, and of plant origin, but also which technologically behaved more like saturated fats. It's kind of like declaring that driving at 80 MPH (130 KPH) is unsafe, deciding to address this issue by selling only cars that can reach 50 MPH (80 KPH) because arguably those cars are safer, but then not being satisfied with the performance of those cars, so "suping" them up so that they can go, say, 70 MPH (110 KPH). Continuing this analogy, let's say that in suping up this lower performance car you inadvertently made the cars less safe at 70 MPH than the original car was at 80 MPH. And that's basically what happened with trans fats, where the problem was that in suping up the unsaturated fats, a new kind of unsaturated fat was born, the trans fat, which turns out to be far worse for you than saturated fats. Though due to government regulation the presence of trans fats in foods is waning, nonetheless beware of foods that contain in their ingredients list the words, "partially hydrogenated". Fully hydrogenated oils, by contrast, are completely lacking in unsaturation so are not trans fats though nevertheless do have the distinction of being unsaturated fats that have been turned chemically into saturated fats.

Links to terms of possible interest: Cis bond, Cis fat, Cis polyunsaturated fatty acid, Double bond, Fatty acid, Trans bond, Trans fat Trans unsaturated fatty acid

The above video provides a nice, balanced perspective on why trans fats are "bad", though beware that fatty acids and even simply hydrocarbons are shown as "fats" and that the example polyunsaturated hydrocarbon is chemically impossible, i.e., count the number of bonds around individual carbons in the example and you will note more than four! Still, the video is a nice introduction to what trans fats are and why they are a problem.

The above video considers the history, at least as I personally recall/understand it, of why we have trans fats and, thankfully, why they are no longer all that much of a problem.

Cholesterol

Multi-ringed, slightly hydrophilic lipid that is a common constituent of mammalian lipid bilayers.

The "problem" of dietary cholesterol isn't quite a myth, but it's close. It makes some sense: Cholesterol deposits found on arterial walls impede arterial blood flow, more cholesterol in the blood "obviously" must lead to more arterial deposits, so more cholesterol in the diet must result in more cholesterol in the blood so more cholesterol deposited on arterial walls. The solution? Stop eating eggs (which are relatively high in dietary cholesterol). To a degree, all of these things are true, but only to a degree. Cutting back on dietary cholesterol can be important for those who suffer especially from a hereditary predisposition to hypercholesterolemia, that is, high levels of cholesterol in the blood, but even here it is not so much dietary cholesterol that is the problem. Instead, cholesterol is a necessary body molecule that is produced by the liver even if no cholesterol is found in the diet. What appears to be particularly important with regard to the depositing of cholesterol on arterial walls are LDLs vs. HDLs in the blood, with the former leading to greater deposition and the latter to less deposition. It is not dietary cholesterol, however, that substantially influences LDL and HDL levels but instead the dietary intake of other fat types. Saturated fats and particularly trans fats are bad in this regard. So the worst thing you can do with regard to the cholesterol and cardiovascular disease may be to skip the eggs and replace them with something that is rich in trans fats, or at least that seems to be more or less the current understanding in this area.

Links to terms of possible interest: Blood cholesterol levels, Cardiovascular disease, Cholesterol, Dietary cholesterol, Fatty acid, HDL, High-density lipoprotein, LDL, Low-density lipoprotein, Lipoprotein, Phospholipid, Triglyceride, Triglycerides

The above video spends a good amount of time on LDLs and HDLs; they kind of equate saturated fats and cholesterol towards the end, however, which is an oversimplification.

This video considers the consequences of excess cholesterol, though note that lipoproteins are not cells!

LDLs	Protein-lipid complexes that carry cholesterol and other lipids to body cells from the liver.
	LDL stands for low-density lipoprotein and often are referred to as the "bad cholesterol" because of their propensity to deliver cholesterol to artery walls.

HDLs	Protein-lipid complexes that carry cholesterol and other lipids from body cells to the liver.
	HDL stands for high-density lipoprotein and often are referred to as the "good cholesterol" because of their propensity to remove cholesterol from artery walls.

Salt (dietary)

Particularly sodium chloride which is used as a food flavor enhancer as it stimulates in a pleasurable manner our tongue taste receptors.

Sodium, as found in large quantities in salt, i.e., table salt, is crucial to health. It is crucial to our health, in fact, to the point that we crave it, hence its desirability as a flavor enhancer of food. The pre-industrial age diet was relatively low in sodium and also relatively high in potassium (both of which are "group 1" metals), and hence our bodies tend to hold on to sodium but less so potassium. The modern diet is high in sodium and low in potassium, and this reversal is potentially problematic. The result can be an increase in blood pressure, with negative consequences for cardiovascular health, but this observation may be true for only a subset of the population (i.e., salt-sensitive individuals). The harmful effects of excessive sodium intake, versus grossly excessive, as a consequence is not at all certain. Note that the converse, too little salt in one's diet or instead the loss of excessive salt such as due to sweating, can also be dangerous.

Links to terms of possible interest: Dietary sodium, NaCl, Sodium, Sodium chloride, Potassium

The video provides a good discussion of where salt tends to come from in our diets as well as the related problem of too little potassium in our diets.

Water (dietary)

Primary liquid constituent of fluids as well as many solids that we take into our bodies and whose intake is balanced by various means of excretion.

Contrast dietary water with metabolic water, that is, the water that instead is generated in the course of cellular respiration (which is the oxygen-requiring means by which cells generate ATP). In fact, metabolic water makes a significant contribution to our daily water needs along with the water that is found in food as water. Thus, when suggestions are made that you take in a certain amount of water every day, it is important to take into account that even without drinking water you still are replenishing, at least to a degree, your body's water supplies on a daily basis and doing so simply by eating and also catabolizing food.

Alcohol (dietary)

Intoxicant consisting of ethanol and which is worth ~7 Calories per gram to us in energy.

The alcohol that we consume as a supplement to our diets consists of the organic compound known as ethanol. Ethanol is a two-carbon alcohol that is a byproduct, along with carbon dioxide, of fermentation as effected by yeasts. This, for us and our consumption of dietary alcohol, consists particularly of the yeast Saccharomyces cerevisiae, also known as brewer's yeast, but which also makes up baker's yeast.

The above video provides some common sense discussion of the downsides and alcohol consumption particularly while dieting, as told from the perspective of athletic training.

Major minerals (dietary)

Calcium, Phosphorus, Magnesium, Sulfur, Sodium, Potassium, and Chloride.

Minerals are nutrients that are required in our diets mostly as individual atoms (or, as more correctly stated, individual ions). This is rather than as molecules, which instead consist of more than one atom chemically bonded together. Sulfur is a bit of an exception in this regard as it is found particularly as a component of sulfur-containing amino acids. These minerals can be differentiated into those that are required by the body in relatively large quantities versus those that are required instead in relatively small quantities. The major dietary minerals are those that are required in relatively large quantities. These tend to be used structurally (i.e., calcium and phosphorus), as important electrolytes in fluids such as blood or cytoplasm (e.g., sodium and potassium, but also chloride), or as components of substantial numbers of biologically important compounds (magnesium and sulfur).

Links to terms of possible interest: Dietary elements, Dietary minerals, Elements, Major dietary minerals, Minerals, RDA, Recommended daily allowance

Trace minerals

Iron, Iodine, Fluoride, Zinc, Manganese, Selenium, and Copper.

Contrasting major dietary minerals/elements are trace elements, which are required in substantially smaller quantities. These elements are found in association with body molecules that are produced in relatively small quantities, e.g., serving as inorganic cofactors of enzymes or instead as constituents of hormones. In addition, fluoride as found in trace quantities in tooth enamel serves as a cavity-preventing agent. Note that, as also is true for major dietary minerals, the form or instead circumstances with which a trace mineral is presented to the body can affect its availability to the body.

Vitamins

Coenzymes that are required in the diet for the maintenance of health.

Micronutrients are required in relatively small quantities and do not serve either as energy supplies or as the building blocks of the macromolecules making up our bodies. Instead, in the case of vitamins as micronutrients, they typically supply important non-amino-acid-based chemistries that allow the enzymes to perform specific catalytic functions (as too is the case with many of the minerals that are required in the diet in only trace amounts). Vitamins, by definition, are only those organic cofactors, that is, coenzymes that the body cannot synthesize on its own and therefore which must be obtained in the diet or from other sources (e.g., sunlight or from our own intestinal bacteria, in the case vitamins D and K, respectively). All required cofactors that the body cannot synthesize are necessary components of diets, including what we call vitamins as well as various minerals.

A nice though very basic introduction to what vitamins are all about.

The above video is Dr. Andrew Weil's take on vitamins and heath. A very interesting perspective on the so-called dangers of vitamin E.

Water-soluble vitamins	Various B, Biotin, C, Folic acid, Niacin, and Pantothenic acid.
	Excretion via the kidneys of water-soluble vitamins is an ongoing process, requiring more or less daily replenishment of body stores. That is, these vitamins are not appreciably stored by the body so optimal levels are sustained only through regular intake in one's diet.

Fat-soluble vitamins

A, D, E, and K.

The implication of a vitamin being fat soluble comes about both in terms of its acquisition (which optimally occurs in association with dietary fat) and its storage within the body. Particularly, and unlike water-soluble vitamins for which we need a more or less daily supply to balance losses due to excretion, the fat-soluble vitamins are stored within fatty tissue over long periods. The result is a potential to build up supplies as well as to draw upon those supplies during times when these vitamins are, for whatever reason, less available in our diets. Note that fat-soluble vitamins also can exist in different chemical forms, ones that are available to the body in different ways or to differing degrees.

Goiter

Disease associated with dietary iodine deficiency.

A goiter is an enlarged thyroid gland. Worldwide as well as historically this enlargement was most typically associated with deficiencies in the mineral, iodine. Given sufficient supplies of iodine in the diet, which is typically the case within more developed societies (and given supplemental iodine availability, particularly as an additive to salt), goiters instead are more typically associated with autoimmune disease involving the thyroid gland. Treatment of goiters often is a relatively straightforward process.

Links to terms of possible interest: Dietary iodine, Goiter, Iodine, Thyroid gland

The above video provides a quick rundown of what goiters represent.

Night blindness	Disease associated with vitamin A deficiency.
	Night blindness is associated with vitamin A deficiency, so from a dietary perspective this is one consequence of insufficient vitamin A intake. Vitamin A deficiencies also can lead to death, though an early sign of such deficiency is night blindness.

An overview of night blindness and its multiple causes.

Pernicious anemia

Disease associated with vitamin B12 deficiency.

This vitamin B12 deficiency as seen with pernicious anemia is primarily a consequence of autoimmune loss of those cells of the stomach that are responsible for releasing what is known as intrinsic factor. Intrinsic factor is a protein that binds to vitamin B12 and facilitates its absorption within the ileum of the small intestine. In the absence of sufficient uptake of vitamin B12 there is a failure by the body to produce red blood cells, resulting in anemia, that is, a reduction in the oxygen-carrying capacity of the blood due to quantitative or qualitative declines in red blood cell populations.

The above video provides a short overview of the cause and consequence of pernicious anemia.

Scurvy

Disease associated with vitamin C deficiency.

The major pathology that stems from a vitamin C deficiency occurs due the requirement for vitamin C to synthesize the protein collagen. Collagen is the primary structural protein of the body and a key constituent of especially fibrous connective tissue. Without collagen production for the sake of collagen replacement, connective tissues fail and this connective tissue failure results in many of the symptoms of scurvy. Scurvy is seen primarily in populations, such as of sailors of yore, who were subject during extended voyages to long periods without access to fresh foods, particularly to fresh fruits and vegetables.

Rickets

Disease associated with vitamin D deficiency.

Rickets also is associated with calcium or phosphorus deficiencies, all as normally supplied in the diet. These three nutrients together are required for a proper hardening of the bones (ossification). Calcium and phosphorus make up the actual ossification of bone (in the form of calcium hydroxyapatite). Vitamin D instead and by contrast is required for the proper uptake (absorption) of calcium in the diet. Thus, too little vitamin D → too little uptake of calcium → impaired ossification → bones that either are brittle or deformed or both. Rickets is seen primarily in children who are suffering from some degree of starvation.