The dietary sugars are linked to aging (fructose,
galactose) because in the cell their reactive products of metabolism damage the
mitochondria and because of glycation.
Glycation occurs when a monosaccharide latches on to a protein and
adversely affects their functions. Because
of this saturated fats, and monounsaturated fats unsaturated fats are the best
sources of energy. The various health
issues with the other sources of energy are explained in the following links on
transfats and polyunsaturated fats.
Carbohydrates are polyhdroxy aldehydes, poyhydroxy ketones,
compounds that can be hydrolyzed to them.
A carbohydrate that cannot be hydrolyzed to a simpler compound is called
a monosaccharide; hydrolyzed to two
mono-hydrides is called a disaccharide, and
polysaccharide for many monosaccharide
Glucose (blood sugar) also known as D-glucose,
dextrose. The open chain form is
unstable and spontaneously tautomerized to the cyclic form. One reason might
be that glucose has a
lower tendency, relative to other hexose sugars, to react non-specifically with the amino groups of proteins. This
reduces or destroys the function of many enzymes. The low
rate of glycation
is due to glucose's preference for the less reactive cyclic isomer.
Nevertheless, many of the long-term complications of diabetes
failure, and peripheral neuropathy) are probably due to
the glycation of proteins or lipids. In
addition of glucose to proteins by glycosylation
is often essential to their function.
Glucose is the human body's key source of energy, through aerobic
respiration, providing approximately 3.75 kilocalories
energy per gram. Starch, cellulose, and glycogen
("animal starch") are common glucose polymers (polysaccharides). Most dietary carbohydrates contain glucose,
either as their only building block, as in starch and glycogen, or
together with another monosaccharide, as in sucrose and lactose.
Sucrose (common name “table sugar”)
is glucose and
fructose glycemic index of 80 (honey 75)
humans and other
mammals, sucrose is broken down into
its constituent monosaccharides, glucose and fructose, by sucrase or isomaltase glycoside hydrolases, which are located in the
of the microvilli
lining the duodenum.
Starch or amylum is a carbohydrate consisting
of a large
number of glucose units
joined by glycosidic bonds.
This polysaccharide is produced
green plants as an
energy store. It
is the most common carbohydrate in human diets and is contained in large
amounts in such staple
foods as potatoes, wheat, maize (corn), rice, and cassava.
is a multi-branched polysaccharide that serves as a form of energy storage
in animals and fungi. It is stored primarily in the cells of the liver and the muscles, and
functions as the secondary long-term energy storage (with the primary energy
stores being fats held in adipose tissue).
Muscle cells lack the enzyme glucose-6-phosphatase, which is required to
pass glucose into the blood, Glycogen is the analogue of starch, a glucose
polymer in plants,
and is sometimes referred to as animal starch.
is a monosaccharide. When combined with glucose
(monosaccharide), through a dehydration reaction, the result is the disaccharide
lactose. Galactose metabolism, which
converts galactose into glucose, Galactose is found in dairy
products, sugar beets, and other gums
It is also synthesized by the body, where it forms part of glycolipids
in several tissues. Galactan can be converted to galactose by hydrolysis.
Malt is germinated cereal grains that have been dried in a process known as
"malting". The grains are made to germinate by soaking in water, and are then halted from germinating
further by drying with hot air. Malting grains develop the enzymes required to modify the grain's starches into sugars, including the monosaccharide glucose, the disaccharide maltose, the trisaccharide maltotriose, and higher sugars
called maltodextrines. It also develops
other enzymes, such as proteases, which break down the
proteins in the grain into forms that can be used by yeast. Malt also contains
small amounts of other sugars, such as sucrose and fructose, which are not
products of starch modification but were already in the grain. Barley is the most commonly malted grain, in part because of its
power or enzyme content, though wheat, rye, oats and rice are also used.
maltobiose or malt
sugar, is a disaccharide formed from two units of glucose. Maltose is the
disaccharide produced when amylase
breaks down starch. It is found in
germinating seeds such as barley as they break down their starch stores to use for food. It is
also produced when glucose is caramelized. Maltose is a component of malt,
Fructose or levulose
(from 2004 article with updates from 2012) is a simple sugar (monosaccharide)
found in many foods and one of the three most important blood
sugars along with glucose and galactose, all of
which are directly absorbed . Honey; tree fruits; berries; melons; and some root vegetables,
such as beets, sweet potatoes, parsnips and onions, contain fructose, usually
in combination with sucrose and glucose. Fructose is also derived from the digestion of sucrose, a
disaccharide consisting of glucose and fructose that is broken down by enzymes during
digestion. Fructose is the sweetest naturally occurring sugar, estimated to be
twice as sweet as sucrose. All
three dietary monosaccharides are transported into the liver by the GLUT2
is often recommended for,
and consumed by, people with diabetes
mellitus or hypoglycemia, because it has a very low Glycemic Index (GI
23) relative to cane sugar (sucrose) [rated
at 100]. However, this benefit
is tempered by concern that fructose may have an adverse effect on plasma lipid
and uric acid levels, and the resulting higher blood levels of fructose can be
damaging to proteins (see below). The low GI is due to
the unique and lengthy metabolic pathway of fructose,
which involves phosphorylation and a multi-step enzymatic process in the liver.
See health effects and glycation for further information.
Fructose depends on glucose to carry it into the blood stream
and then GLUT-2 .
Absorption of fructose without glucose present is very poor, and excess
fructose is carried into the lower intestine where it provides nutrients for the
existing flora, which produce gas. It may also cause water retention in the
intestine. These effects may lead to bloating,
loose stools, and even diarrhea depending on the amounts eaten and other factors.
has been hypothesized to
cause obesity ,
elevated LDL cholesterol and triglycerides,
leading to metabolic syndrome. Unlike animal experiments, some human experiments have
failed to show a correlation between fructose consumption and obesity. Short
term tests, lack of dietary control, and lack of a non-fructose consuming
control group are all confounding factors in human experiments. However, there
are now a number of reports showing correlation of fructose consumption to
obesity, especially central obesity which is generally regarded as the most
dangerous type. (Wylie-Rosett, 2004)(Havel, 2005)(Bray, 2004) (Dennison, 1997). [Article
misses it role in non-alcoholic
fatty liver disease, which causes first insulin resistance in the liver which
develops into insulin resistance in the adipose and muscle tissues, and
eventual it can progress to type-2 diabetes.
This pathway is dependent upon a high carb and high sugar diet. Glucose
raises insulin which cases fat
storage, and this leads to a fatty liver, since fructose is only metabolized in
the liver where it is converted into fat.
Population studies fail to adequately uncover this role of fructose
because the high intake of sugar, such as from sodas and fruit drinks, often is
temporary, and could happen decades early.
A large percentage of the obese population reduce their sugar
consumption as part of their attempt at weight control.]
Compared to sucrose
Studies that have compared high-fructose corn syrup (an ingredient in
nearly all soft drinks sold in the US) to sucrose (common
table sugar) find that most measured short term physiological effects are
equivalent.[dubious – discuss];
however, studies that compare the long term effects between sucrose and
fructose have yet to be conducted. For instance, Melanson et al. (2006),
studied the short term effects of HFCS and sucrose-sweetened drinks on blood
leptin, and ghrelin levels.
They found no significant differences in any of these parameters. This
is not surprising since sucrose is a disaccharide that digests to 50% fructose
and 50% glucose, whereas the high-fructose corn syrup most commonly used on
soft drinks is 55% fructose and 45% glucose. The difference between the two
lies in the fact that HFCS contains little sucrose, the fructose and glucose
being independent moieties. Even so, Melanson et al. found
that "Longer-term studies on connections between HFCS, potential
mechanisms, and body weight have not been conducted".
Fructose also chelates minerals in the blood. This effect is especially
important with micronutrients such as copper, chromium and zinc. Since these
solutes are normally present in small quantities, chelation of small numbers of ions
may lead to deficiency diseases, immune
system impairment and even insulin resistance, a component of type II diabetes
(Higdon). Fructose is often
recommended for diabetics because it does not trigger the production of insulin
by pancreatic β
the result of a sugar molecule, such as fructose or glucose, bonding
to a protein
or lipid molecule
without the controlling action of an enzyme. All blood
sugars are reducing molecules. Glycation may occur either inside (endogenous)
or outside (exogenous) the body. Enzyme-controlled addition of sugars to
protein or lipid molecules is termed glycosylation;
this process is less haphazard than glycation. Much of early laboratory
research work on fructose glycations used inaccurate assay techniques that
drastically understated the importance of fructose in glycation formation
(Ahmed & Furth 1992).
is a reducing
sugar, as are all monosaccharides. The spontaneous addition of single sugar
molecules to proteins, known as glycation, is a significant cause of damage in diabetics.
Fructose appears to be as dangerous as glucose in this regard and so does not
seem to be the answer for diabetes (McPherson et al, 1988). This may be an important contribution to senescence
and many age-related chronic diseases (Levi & Werman 1998). Compared with consumption of high glucose beverages, drinking high
fructose beverages with meals results in lower circulating insulin and leptin levels, and
levels after the meal. Since
leptin and insulin decrease appetite and ghrelin increases appetite, some
researchers suspect that eating large amounts of fructose increases the
likelihood of weight gain. Probably more
important to advanced life is the low tendency of glucose, by comparison to
other hexose sugars, to non-specifically react with the amino groups of proteins. This
reduces or destroys the function of many enzymes. The low rate of glycation is due to glucose's
preference for the less reactive cyclic isomer.
Nevertheless, many of the long-term complications of diabetes (e.g.,
failure, and peripheral neuropathy) are probably due to
the glycation of proteins or lipids. Glycosylation
is another important type of reaction undergone by glucose.
Fructose is used as a substitute for sucrose (common sugar) because it is
less expensive and has little effect on measured blood glucose levels. Often
Fructose is consumed as high fructose corn syrup which is corn syrup
which has been enzymatically treated, by the enzyme glucose
isomerase, to convert a portion of the glucose into
fructose thus making it sweeter. This is done to such a degree to yield corn syrup
with an equivalent sweetness as sucrose by weight. While most carbohydrates
have around the same amount of calories, fructose is sweeter, so manufacturers
may use less fructose to get the same sweetness. The free fructose present in fruits, their
juice, and honey
is responsible for the greater sweetness of these natural sugar sources.
glycations and Advanced
Glycation End products (AGEs)
are typically formed when sugars are cooked with proteins or fats. Temperatures
over 120°C (~248°F) greatly accelerate the reactions, but lower temperatures
with longer cooking times also promote their formation. Exogenous iterally means
'outside the body' and refers to as
"dietary" or "pre-formed."
These compounds are absorbed by the body during digestion
with about 30%
efficiency. Browning reactions (usually Maillard type reactions) are evidence
of pre-formed glycations. Indeed, sugar is often added to products such as French fries
and baked goods to enhance browning. Glycation may also contribute to the
formation of acrylamide (Stadler et al 2002), a potential carcinogen,
during cooking. Until recently, it was thought that exogenous glycations and
AGEs were negligible contributors to inflammation and disease states, but
recent work has shown that they are important (Vlassara, 2005). Although most
of the research work has been done with reference to diabetes, these results
are most likely important for all people as exogenous AGEs are implicated in
the initiation of retinal dysfunction, cardiovascular diseases, type II
diabetes, and many other age related chronic diseases.
Food manufacturers have added AGEs to foods, especially in
the last 50
years, as flavor enhancers and colorants to improve appearance (Peppa et. al.
2003). Foods with significant browning, caramelization, or with directly added
preformed AGEs can be exceptionally high in these pro-inflammatory and disease
initiating compounds. A very partial listing of foods with very high exogenous
AGEs includes: donuts, barbecued meats, cake, and dark colored soda pop
(Koschinsky, et. al. 1997).
glycations occur mainly in the bloodstream to a small proportion of
the absorbed simple sugars: glucose, fructose and galactose. The balance of the sugar molecules is used for
metabolic processes. It appears that fructose and galactose
have approximately ten times
the glycation activity of glucose, the primary body fuel (McPherson et
al 1988). Glycation is the first step in the evolution of these molecules
through a complex series of very slow reactions in the body known as Amadori
reactions, Schiff base reactions, and Maillard
reactions; all lead to advanced glycation end products (AGEs). Some AGEs are
benign, but others are more reactive than the sugars they are derived from, and
are implicated in many age-related chronic diseases such as: type II diabetes
mellitus (beta cell damage), cardiovascular diseases (the endothelium,
fibrinogen and collagen are damaged), Alzheimer's disease (amyloid proteins are side
products of the reactions progressing to AGEs), cancer (acrylamide
and other side products are released), peripheral neuropathy (the myelin is attacked),
and other sensory losses such as deafness (due to demyelination) and blindness
(mostly due to microvascular damage in the retina). This range of diseases is
the result of the very
basic level at which glycations interfere with molecular and cellular
functioning throughout the body and the release of highly-oxidizing side
products such as hydrogen peroxide.
Glycated substances are eliminated from the body slowly,
since the renal
clearance factor is only about 30%. This implies that the half-life of a
glycation within the body is about double the average cell life. Red blood
cells are the shortest-lived cells in the body (120 days), so, the half life is
about 240 days. This fact is used in monitoring blood sugar control in diabetes by
monitoring the glycated hemoglobin level. As a consequence, long-lived cells
(such as nerves, brain cells) and long-lasting proteins (such as DNA, eye
crystalline, and collagen) may accumulate substantial damage over time.
Metabolically-active cells such as the glomeruli in the kidneys, retina cells in the
eyes, and beta
cells (insulin-producing) in the pancreas are also at high risk of damage.
The epithelial cells of the blood vessels are damaged directly by glycations,
which are implicated in atherosclerosis, for example. Atherosclerotic plaque
tends to accumulate at areas of high blood flow (such as the entrance to the
coronary arteries) due to the increased presentation of sugar molecules,
glycations and glyc ation end-products at these points. Damage by glycation
results in stiffening of the collagen in the blood vessel walls, leading to
high blood pressure. Glycations also cause weakening of the collagen in the
blood vessel walls, which may lead to micro- or macro-aneurisms; this may cause
strokes if in the brain.
 It is
tobacco science to recommend fructose for diabetics, especially those with
type-2 diabetes (adult onset). The path
to their conditions starts with a fairly consistent consumption of more than 40
grams of fructose dialing along with a high carb diet, and no prolonged periods
of fasting. Fructose is metabolized only
in the liver, where most of it is converted into fat. This fat gradually accumulates
in the liver
resulting in a fatty liver, called Non-Alcoholic Fatty Liver Disease (NAFLD),
which depending on lifestyle often results in insulin resistance. Insulin resistance
is the prerequisite condition
for progression into type-2 diabetes.
Thus to recommend fructose and a high carb diet is to promote the
progression of type-2 diabetes.