Fructose

Glucose: C6H12O6

Aldohexose

Fructose is an isomer of Glucose

Isomers are molecules that share the same atomic ratio but are arranged in different configurations. Fructose and Glucose both have the same molecular formula: C6H12O6

Both Fructose and Glucose are formed during intermediate steps of photosynthesis. Plants will attach Fructose and Glucose together to produce Sucrose. While every cell can metabolize Glucose, Fructose must be metabolized in the liver and overconsumption of Fructose has been implicated as a chemical of concern.

Fructose: C6H12O6

Ketohexose

In chemistry, saccharide is another word for "sugar." Fructose is a monosaccharide.

Here are some of the mono-saccharides (think mono = one!) Glucose is the primary monosaccharide our body metabolizes, but the chemical structures of other saccharides only differ in a few atoms and can be rapidly converted to Glucose in the body.

Fructose is a monosaccharide produced in fruit, and it gets metabolized a little differently than Glucose, usually in the liver.

Mono = 1; Di = 2; Tri = 3; Poly = 4+

Lactose is a disaccharide.

People with Lactose intolerance don't have enough enzymes to break this down into the monosaccharide pieces of Galactose and Glucose. Instead, tiny microbes get to eat on Lactose, which in turn produce methane gas responsible for other digestional issues.

Sucrose is a disaccharide.

Sucrose is the molecule that makes up granulated table sugar. Sucrose is a natural 50/50 combo of Fructose and Glucose. Hi-Fructose Corn Syrup (HFCS) is 55% Fructose/45% Glucose. Both HFCS and Sucrose are added in a lot of foods we eat. The huge amount of Fructose we consume in the Standard American Diet (SAD) has been shown to be responsible for a number of our national dietary issues.

Cellulose is a polysaccharide

Cellulose is polymer of Glucose that plants produce to make their cell well more sturdy and rigid. On the macro scale, this ultimately becomes the hard shelled bark that protects a tree. Humans do not produce the enzyme needed to break down Cellulose into Glucose, so it passes through our digestive system as fiber.

Saccharides have a lot of polar chemical bonds that attract water. Because these carbon-compounds are often found in a hydrated environment, saccharidges are also known as "Carbohydrates".

Glucose is overwhelmed by his Water stans. What a chad.

Foods rich in carbohydrates. Yes, even the paper bag is a carb (Cellulose)

Glycolysis and the Citric Acid Cycle are the pathways that generate ATP for our cells. Fructose is an intermediate in these pathways.

Glucose metabolism is regulated at the cellular level. Each step of Glycolysis is highly regulated by a number of enzymes and cellular processes. We are unable to generate unlimited ATP by consuming unlimited food because of these restrictions (which is good for us!). While Glucose is isomerized to Fructose in the pathway (Fructose-6-phosphate and Fructose-1,6-bisphosphate), direct Fructose metabolism circumvents many of the aforementioned regulations of Glucose metabolism. Because of this, overconsumption of Fructose can be damaging to our entire body, especially the Hepatic cells.

Glycolysis

In Glycolysis (pictured above), Glucose is converted into Pyruvate. This process creates 2 ATP for the cell and often occurs in the cytosol.

Citric Acid Cycle

In the Citric Acid Cycle (aka Kreb's Cycle/TCA), pyruvate is further metabolized to harness more chemical energy. This cycle produces more ATP and high energy molecules (NADH and FADH2) that get processed in the Mitochondria. This is also where protein and fat are metabolized.

The levels of Fructose consumed in the Standard American Diet are elevated because of industrialization. The human body hasn't caught up.

The human body has an evolutionary background in hunting and gathering. We have an have an intensely positive relationship with high caloric foods, like sweet fruit and berries, since finding them in nature would have been very beneficial to our lineage. Those ancestors that developed the ability to hunt out and derive pleasure from sweet fruit were rewarded with far more nutrients and offspring.

Our society has evolved more rapidly than our bodies, however. The overproduction and overconsumption of Fructose has led to many metabolic diseases across the world. Where once we ate Fructose in moderation, rewarded by the rare sight of a ripe fruit in the right season, humans now consume hundreds of pounds of this substance due to modern food production.

The main organ responsible for processing Fructose is the liver. While humans have designed machines and techniques to maximize our ingestion of Fructose, this important organ can only tolerate so much of the compound.

Chemical Pathway of Glucose v Fructose

Hepatocytes are the cells in the liver that are responsible for filtering the blood of many metabolites, including alcohol and Fructose. The liver does not have mechanisms for regulating blood-Fructose levels, so ALL Fructose gets processed. If there are no immediate energy needs, the liver stores this extra carbon in the form of adipose (fat) tissue.

When exposed to high levels of certain chemicals, the liver suffers damage in the following stages:

Stage 1: Inflammation
Stage 2: Fibrosis
Stage 3: Cirrhosis
Stage 4: Liver Failure

High fructose exposure has similar impacts on the liver as Hepatitis or alcoholism. Non-alcoholic fatty liver disease (NAFLD) progresses to non-alcoholic steatohepatitis (NASH) when scar tissue prevents normal liver function.

Cirrhosis is scarring of liver tissue that has irreversible consequences. Patients with high levels of cirrhosis must undergo a transplant. In 2018, the waitlist for a liver organ donor was 11,844.

While Hepatitis C cases dropped significantly for the last 20 years, reducing cirrhosis from that source, non-alcoholic fatty liver disease rates have continued to rise.

In addition to liver damage, Fructose consumption increases visceral fat, the adipose tissue that surrounds the organs. Visceral fat has large implications for other metabolic disorders, including diabetes.

How and why do we make so much Fructose?

Fructose is "healthy"

1953

President Eisenhower's heart attack made heart disease a public health issue. Alternate theories about the cause of heart disease arose; was fat to blame or was sugar the cause?

1961

Ancel Keys was the scientist who blamed fat, not sugar, for the epidemic of heart disease. His anti-fat propaganda gathered steam, while "healthy" low-fat sugar alternatives became popular.

1984

The markets respond to the anti-fat rhetoric of Keys. Fat-free foods become vogue, and food producers and stores begin to carry massive amounts of low-fat foods. In order to keep these foods enjoyable, the sugar content is increased across the board.

Fructose is "cheap"

Because of our national dependence on sugar and fuel, corn subsidies have long been a staple of American commerce. Over time, the corn subsidies have taken on the lion's share of agriculture programs in the US.

Because of this farming security, corn production has consistently increased over the last century. Because of this increased production, corn prices have remained low despite inflation. Food producers eager to add cheap calories to their products can opt for inexpensive corn based ingredients.

All of these factors have led to a massive spike in corn-based high-fructose corn-syrup (HFCS) in the US. HFCS sweeteners now outweigh sucrose calories in the standard American diet.

Fructose is "plentiful"

Glucose Isomerase is an enzyme made of multiple protein subunits. Enzymes are proteins that speed up chemical reactions. Humans do not synthesize Glucose Isomerase.

Glucose Isomerase is able to catalyze all of the molecular rearrangements to convert Glucose to Fructose. Each step happens rapidly and creates high yield.

Glucose isomerase was first isolated by Marshall and Kooi in 1957 from Pseudomonas hydrophila. This allowed Fructose to be produced commercially in large volumes, leading to the widespread adoption of High Fructose Corn Syrup as a replacement to cane sugar.

Fructose is "sweet"

Taste "buds" are made of multiple cell types

Our sense of taste is defined by chemical interactions between receptors and the molecules that stimulate those sensors. While it was once believed that certain spots of the tongue were responsible for different sensations of flavor (sweet, sour, salty, bitter, umami), each area of the tongue expresses taste buds capable of registering all flavors. Certain molecules like fructose stimulate far more receptors and thus taste sweeter.

The best treatment for Fructose addiction is information

Just as Ancel Keys changed public opinion and forced food producers to make "low-fat" foods, documentaries that showcase public-health issues of certain foods can lead to massive social changes.

"Super Size Me", a documentary where one man ate McDonalds exclusively for a month, caused such public outlash against McDonalds that they removed their super-sized drink and fry options. Less soda = less fructose.

But just as Ancel Keys demonstrated last century, no public health information is definitive and unchanging. As humans learn more about our physiology, there will always be new health trends. Be cautious about the information fed to you, and always ask "who profits from this?"

Fructose OC (15 points)

Create a Google Form quiz about Fructose

Copy the first 5 questions from the template (1 pt)

Include pictures in the template questions (1 pt)

Include all 3 question types (dropdown/MC/checkbox) (1 pt)

Include a form header/style (1 pt)

Make the form a quiz with correct answers and points (1 pt)

Create 5 additional Fructose-based questions (1 pt each, 5 total)

Give the quiz to 5 members of your family. Embed the results in your page (1 pt each, 5 total)

Fructose Quiz (Brian Smith) (Responses)

Halloween candy tier list (5 points)

Create your favorite candy tierlist from one of the many tierlist making sites. (2 pts). Collect tier list data with 3 other non-students (family/faculty) (1 pt/list, 3 points total)