 Our distant ancestors lived in a world of scarce available resources. The kind of resources they had available to them before the harnessing of fire for cooking were uncooked animal flesh, nuts, and seeds, and a real delicacy would have been ripe fruit. Fruit, through the action of co-evolution, has been selected for millions of years to be delicious and desirable to animals who act as vectors for seed dispersal. There's no pressure to be especially nutritious, but anything which was overtly toxic was certainly selected against. The primate line began to expand in size and territory, and plants adjusted to meet our tastes and preferences. Our ingestion of delicious fruit benefited us, but it also served as a great way to relocate seeds to distant locations. No doubt, many a plant began its life in the latrine pit left behind a small band of hunter-gatherers. What is it that we like about fruit? It's one of the few natural sources of abundant sugars. Simple carbohydrates are easy for the plant to make, easy for the animal to digest and absorb, and represent an abundant source of food energy to be given as a bribe from the plant to the animal. The seed often contain the more dense energy source, oil or fat, but this is intended as a starter fund to be used by the new plant. Coding the oil with an easy to digest sugary coating might serve to discourage damage to the seed itself. Modern humans can have sugar in abundance. We can pour tree-derived maple syrup all over our pancakes, sweeten our coffee with the refined and crystallized juice of a woody grass, and enjoy a delicious mix of sweet berries, bananas or other fruit, all mixed with a yogurt that has been sweetened with a sugary extract of corn. If our primate ancestors could see us now, they would be seriously jealous of our delicious diet. But those instincts for sweetness, honed over millions of years of evolution, are a big part of the problem with the health of modern humans. We are still eating as though the scarcity of winter were just around the corner, and we need to put on a layer of fat. We've supplanted the modest sweetness of natural fruits with concentrated and crystallized essence of ripe fruit. Our brains are preparing us for a shortage that will never come. We are urged to eat like animals that must regularly flee predators when the real risk for us now is heart disease or cancer. I want to examine some of the research into the health effects of our indulgence in sweetness. I'm going to focus just on sucrose, high fructose corn syrup, and hold off on the non-nutritive sweeteners like aspartame or stevia. I want to lay out for you what the current research supports as good choices and bad choices. As always, I invite comments or responses. I'll start with a review of the basics of sugars. There seems to be a lot of misconceptions about how the different nutritive sweeteners relate to each other. Sugars usually refers to a simple carbohydrate. Carbohydrates are, like the name suggests, made of carbon plus some amount of hydrogen and oxygen in the same ratio as in water, 2 to 1. For example, C6H12O6 is the chemical formula for glucose and also for fructose and galactose. They only differ in the arrangement of bonds inside the molecule. Each of these is called a monomer sugar or reducing sugar. When we join these monomer sugars together with a chemical bond, we get a polymer sugar or polysaccharide like starch or glycogen or cellulose, which are made up of a long chain of simple sugars. For example, cellulose, the plant material that makes up most of paper or wood, trees and leaves, is a very long chain of glucose molecules. The sugar that we are mostly familiar with, sucrose or table sugar, usually made from sugarcane or sugar beets, is actually a dye saccharide, meaning made from two monomer sugars. It is composed of one glucose and one fructose joined by a bond called a glycoside linkage. So we could say that sucrose is 50% fructose and 50% glucose joined together by a chemical bond. High fructose corn syrup comes in many forms, but the one most often used is called HFCS55, which indicates that it's composed of 55% fructose and 43% glucose. The remaining 2% are actually longer polysaccharides similar to starch, and they're a byproduct of the manufacturing process. So table sugar is 50% fructose and HFCS55 is 55% fructose. The only difference is that in the HFCS, the sugars are not joined by a chemical bond. They exist as monomers in solution. Does that matter? Not really. Your body is exceptionally good at breaking that single glycoside bond. You have enzymes that break sucrose into fructose and glucose as fast as it can reach it. Within milliseconds, your body has a hard time distinguishing between sucrose and HFCS, except one has about 5% more fructose and 9% glucose. We shouldn't ignore that small difference either. Why am I emphasizing the fructose here, but not the glucose? Simple. Fructose is the Adolph Hitler of monosaccharides. It's evil incarnate. Okay, no, not quite that bad, but it is the sugar that is most strongly linked to all the health problems we now associate with excess sugar consumption. It's a very long list. Heart disease, non-alcoholic fatty liver disease, lipid dysfunctions, type 2 diabetes, obesity, metabolic syndrome, accelerated aging, gout, memory loss, dental cavities, and many, many more. Why are we even using it then? Get another plot by the Illuminati to destroy people's health? Nothing so glamorous. We use fructose-containing sweeteners because fructose is the sweetest sugar. Fructose is well over twice as sweet as glucose, the other monomer in sucrose. The fructose monomer alone is about 70% sweeter than sucrose, which as I said is partially made from fructose. That means that we should be able to use a little less of it to get the same sweetness, reducing calories and total consumption of fructose. A recent research study suggests that this little difference of 5% more fructose and 9% less glucose may have a larger effect on obesity and metabolic disease. I'd like to go through this specific paper in a separate video because it will provide an excellent example of how to read a research paper. So keep an eye out for it a little later. Here's a quiz question, folks. Anyone remember why it's called fructose? Because it's found in a lot of fruits. Basically any fruit grown on a tree or vine is going to be quite high in free fructose. Dried figs are especially high. Apples, peaches, nectarines, pears, etc. Also, grapes, cherries, yams, carrots, and beets. So when you see that something is labeled no sugar added, look more carefully at the label. They often add something like apple or grape juice instead, which can actually be higher in fructose than high fructose corn syrup. Does that mean you shouldn't eat fruit? Not really. The fiber found in most of these slowed down the absorption of the sugar, so you won't see as much of a spike in blood sugar. I'd advise watching very carefully how much fruit juice and certain low-fiber fruits you're eating or serving your kids if you have concerns. A sugary 12-ounce coke, 355 milliliters to my European viewers, contains about 39 grams of carbohydrate. I assume that about 20 grams of that is pure fructose. The same amount of apple juice may contain 42 grams of sugar, but may actually contain more than 20 grams of fructose. If you want the sweet taste of apple, I suggest you eat the skin and pulp. Other foods that are very high in fructose are applesauce, honey, pears, agave nectar, grape juice, pomegranate juice, and dates and watermelon. Some of these have more fructose per weight than a sugary soda. Here's why HFCS is so evil. It's being overused. We're drowning in it, as the critics say. The politics of corn production in the U.S. are complicated. It's one of our top exports, and keeping it in excess production is politically popular and may be the result of foreign trade policies. We export a lot of ag products, and corn is one of the most fungible of those exports. It can sit in a silo for a long time, and we've found a billion and one uses for it. From the perspective of the environment, it's not a great crop, but from the perspective of yield, it is. Farmers can make a lot of money from it, and politicians seem to love subsidizing corn to keep it cheap, which feeds industrial growth, which supports economic growth in stable prices. It also supports the obesity epidemic and healthcare crisis. Industry loves HFCS because it ships and stores very easily, unlike granular sugar, which is very moisture-sensitive. It's already in solution, so all you have to do is add it to the manufacturing batch, as opposed to granular sugar, which must be dissolved into a simple syrup before addition. The reason HFCS is evil is because we like it so much. I'm not convinced that sucrose is any better, but it's ever so slightly more expensive and harder to add to a liquid product, and that may make a beverage company hesitate for half a second before doubling the sugar content in a soda to cover the fact that they are also adding salt to make you more thirsty. Consumers are driven by their biology, adapted to desire the sweetness of ripe fruit loaded with fructose. Companies are driven by profit to give customers what they're willing to buy. The collision of those two motivations is an obese, diabetic country. HFCS is a problem because kids are drinking sugary sodas at a young age, and as a group, we're drinking too much of them. Our fructose consumption is too high. That's not because HFCS is chemically very different from sucrose. It's because manufacturers like to use a lot of it. We could be killing ourselves just as easily with cane sugar, but it would cost us a few extra bucks a year. HFCS is just putting up handrails and lighted paths on the road to our self-destruction. We're the ones walking along it. So how much added sugar is too much? Don't forget Concordance's first law. Never take medical advice from the internet. A doctor is always your best bet for health advice. However, the Mayo Clinic and American Heart Association both give the same figure. No more than 100 calories for women, no more than 150 calories for men, and less is always better. One can of coke or similar soda is about 100 calories of added sugar, so limit yourself to about that much per day or less. You want a little personal advice from me to you. Pick up the water habit. Add a little twist of lime or lemon and some ice. You'll be a lot more refreshed and a lot healthier as a result. I'm anticipating at least one person in comments is going to promote stevia, a non-chloric sweetener extracted from the stevia plant. This is a very popular sweetener with health-conscious people, but I actually have some concerns about stevia. It's going to have to wait for a later video on the non-nutritive sweeteners like Aspartame and Splinda. But let's just say we don't know much about it, but what we do know is a bit troubling. Stick to natural sweetness of foods if you can. If you can't, focus on moderation. Honestly, I think we all understand that cotton candy is not health food. Neither is a sugary soda. Neither is a giant steak dripping with bourbon butter. Our evolution is working against us here. We crave the things that our distant ancestors were least able to obtain. Ripe fruit, seared meat, salty snacks. Unlike those ancient peoples, we are able to obtain these things at little expense. Now we must learn to master our animal instincts to behave like civilized people. We must demonstrate discipline, restraint, and wisdom in what we eat and what we do. I'll quote something I heard the other day that summarized in exactly seven words how to eat well. Eat food, not too much, mostly vegetables. I think that's the kind of wisdom I can just about handle. Thanks for watching. Every cell of each plant and animal contains genetic information coded onto the DNA molecule.