Dr. Robert Lustig changed my mind. He's an MIT/Cornell medical doctor of endocrinology, speaking on the area of his expertise at UCSF, in a video carried by UC Television. That's pretty credible in my book. There's a lot of content in his video, so I'm going to write it up to understand it better. I'm not saying Dr. Lustig is absolutely correct, I think he's correct and I'm hoping that his ideas pass the peer review of my commenters here.
Short SummaryRegular sugar is just as bad for you as HFCS. "Natural cane sugar", HFCS, and natural fruit juices are equally metabolically harmful because of the fructose. Glucose is fine, but fructose is metabolized by a pathway much more similar to alcohol, which is why constant fructose exposure causes many of the same symptoms that constant acute alcohol exposure causes: hypertension, obesity, pancreatitis, fetal insulin resistance, etc. Fructose consumption (from sugar & HFCS) has increased substantially in the last 30 years coinciding with obesity increases for more reasons than just "calories in / calories out". You are not what you eat; you are what you do with what you eat. Exercise burns some calories, but mostly encourages your body to metabolize the calories in other ways. Whole fruit is good for you in a way that fruit juice isn't because of the fiber. If you want to be healthier, eliminate all sugared beverages (whether soda or juice) and balance your remaining sugar with fiber.
The Obesity EpidemicIt's not just that fat people are getting fatter. The entire weight distribution curve has shifted right. Over the last 30 years everyone weighs an average of 25lbs more than we did 25 years ago. There's a genetic component, but our genetic pool didn't change that much in the last 25 years. "Calories in / Calories out" is not the problem. Obese people are not slothful and gluttonous revelers in gastronomic debauchery, they are victims of poorly running biochemical processes. Even six-month-olds are more obese, and it's not because today's babies are more gluttonous or lazier.
Americans *are* eating more calories than before. Teen boys eat 275 more calories every day. Adult males eat 187 calories more every day. Females eat 335 more calories every day. We're eating the same amount of fat; the big gains have been from sugar. We drink 41% more soft drinks and 35% more fruit drinks. 1 can of soda is 150 calories.The hormone leptin has a reduced ability to stop us from eating because something is interfering with it.
The "low fat" craze exacerbated this problem. Ancel Keys' "Seven Countries" (1980) study found a correlation between dietary fat, LDL, and heart disease. He also noted, but never followed up on, "the intercorrelation of sucrose and saturated fat". High fat diets also tend to be high sugar, and he assumed that the fat was the problem. We've based the last 30 years of public health policy on what may have been a mistake. John Yudkin's Pure White & Deadly got it correct in 1972, alleging a link between heart disease, diabetes, and sugar. mbod told me that blaming fat for heart disease is like blaming the fire department for house fires - there's an obvious correlation, but the causality doesn't work that way.
HFCS and Sugar are the sameWhether you're eating HFCS or regular Sucrose (cane sugar), the chemical proportions are almost the same. Sucrase breaks the bond between glucose and sucrose and the body handles them both the same way. Hunger and satiety responses are no different between HFCS and Sucrose. HFCS is evil not because it's metabolically evil, but because it's cheap (because of corn subsidies) which helps make sugar cheap too. Since 1970, the total amount of sugar+HFCS has increased as it's been added to almost every processed food. We've gone from consuming 73 lbs/yr to 93lbs/yr plus 10 lbs/yr from fruit juices.
The Fructose/Cholesterol ConnectionThere are actually two types of LDL. Pattern A is large and buoyant and can't get under the epithelial cells in the arteries to start plaque formation. Pattern B is small, dense, doesn't float, gets between the epithelial cells, and causes problems. Lab LDL tests count both of these together, which is why triglyceride to HDL ratios predict heart attacks far better than LDL levels. If your triglycerides are low and HDL is high that's good; it means more LDL-A and less LDL-B. High triglycerides and low HDL mean more LDL-B, less LDL-A, and high risk of heart disease. Dietary fat raises LDL-A levels, but carbohydrates raise LDL-B levels, and low fat foods replace fat with sugar, to keep things palatable. Sugar is also added as a browning agent which works via protein glycation cross-linking, which coincidentally is the same process that causes plaques in arteries. Another problem is fiber. 50,000 years ago we consumed 100-300 grams of fiber per day, but modern humans consume about 12, because fiber is removed from processed foods to increase shelf life, decrease cooking time, and make the food easier to eat. Trans fats were a third problem, but food providers are starting to get rid of those.
Fructose is not glucoseIt's 7 times more likely to produce advanced glycation end products that harden arteries. Glucose suppresses the hormone that makes you feel hungry but fructose doesn't. You'll eat more food if you drink soda with your meal (plus the calories from the soda). Beta cells have only glucose receptors. Glucose stimulates insulin production, which stimulates leptin production, which makes you feel full, but fructose doesn't. Most importantly the hepatic metabolism of fructose takes a completely different pathway than glucose. That's how chronic fructose exposure causes metabolic syndrome; obesity, type II diabetes, lipid problems, hypertension, and cardiovascular disease.
Glucose MetabolisysIf we eat two slices of bread we're eating 120 calories of mostly starch, a glucose
Ethanol (Alcohol) MetabolisysEthanol (alcohol) is a carbohydrate also, but it's less good for you. If we drink a 120 calorie shot of Maker's Mark the stomach and intestine consume 10% and the kidneys/muscle/brain consume another 10%. 96 calories hit the liver - 4x as much as the case of glucose. In the liver, ethanol gets converted to acid aldehyde, which cross-links proteins which causes cirrhosis. The acid aldehyde gets converted to acetate which also goes through the TCA cycle, producing citrate (as before) which turns into VLDL fats, but 4x the citrate produces 4x the VLDL, plus fat production (beer belly), plus free fatty acids causing muscle insulin resistance. Some of the Acyl-CoA doesn't make it to VLDL and exits as lipid droplets, causing alcoholic steatohepatitis. The ethanol, acetaldehyde, and Acyl-CoA start the JNC1 enzyme which causes inflammation.
Fructose Metabolisys (Like Ethanol)If we drink a glass of orange juice we'll consume 120 calories of sucrose. 60 is glucose, and as above 80% gets taken up directly by the body and 20% (12cal) hits the liver. All 60 calories of fructose hits the liver, because only the liver can metabolize fructose. Fructose gets metabolized into Fructose-1-Phosphate, and now we have 72 calories to be phosphorylated rather than 24 in the starch situation. The phosphate gets taken from ATP->ADP->AMP->IMP->uric acid, which causes gout and hypertension because uric acid blocks endothelial nitric oxide synthase which makes nitric oxide which lowers blood pressure. When you can't make it your blood pressure goes up, which is why high sugar diets cause gout and high blood pressure. Gout drugs' effectiveness against hypertension further demonstrates the connection between sugar and high blood pressure. The fructose gets metabolized into Dihydroxyacetone-P and Glyceraldehyde on its way to Pyruvate which goes through the same TCA cycle as above producing ATP and citrate. But Dihydroxyacetone-P and Glyceraldehyde can also end up as Xylose-5-Phosphate, which stimulates PP2A which activates Carbohydrate Response Element Binding Protein which activates the AC1/ACC/FAS enzymes that turn citrate into VLDL fats causing de novo lipogenesis - new fat production. This is why high sugar diets are high fat diets. In studies, triglycerides go up after acute fructose exposure. In tests on medical students, 6 days of high fructose feeding caused triglyceride levels to double, de novo lipogenesis went up 5x higher, and free fatty acids (which cause insulin resistance) doubled. The fats that don't make it out of the liver cause non-alcoholic steatohepatitis. The Acyl-CoA and Fructose-1-P both activate JNC1, which serine phosphorylates IRS-1, which is inactive, which prevents insulin from doing its job in the liver, which causes liver insulin resistance, causing the pancreas to work even harder producing higher causing insulin levels causing higher blood pressure and more energy ending up in fat cells causing obesity.
The higher the insulin the less the brain sees leptin; your brain wants you to keep eating because it thinks you're starving. The whole thing becomes a vicious cycle: more fructose means more fat and insulin which means reduced leptin which means more hunger which means you eat more fructose.
(HFCS is not completely bad. Sports drinks contain HFCS because if you've just exercised very strenuously and burned all your liver's glycogen - if you are entirely glycogen-delpeted - HFCS will regenerate glycogen faster than with glucose alone. It makes sense for elite athletes who have just exercised very strenuously to drink HFCS. But most people who drink sports drinks are kids who drink it because sports drinks are socially cool and taste delicious. The original Gatorade - the one that was made famous by helped Florida win the 1970 NCAA championship - tasted terrible. In 1992 when Pepsi bought Gatorade they reformulated it by adding HFCS to appeal to fat kids, not elite athletes.)
Chronic fructose exposure causes 8 of the 12 problems that chronic alcohol exposure causes, because they are metabolized by the liver in very much the same way. They come from the same place, because ethanol is fermented sugar, and the fermentation doesn't change very much from the liver's perspective.
What To Do About ItIf you want to stay healthy, get rid of all sugared liquids. Drink only water and milk. Eat carbohydrates with fiber, and wait 20 minutes before you eat a second portion, to get the satiety signal. "Buy" your screen time with an equal amount of physical activity. If you go out and play for 30 minutes you can watch TV for 30 minutes. In his clinic, these measures work - BMI z-scores steadily decrease from baseline over 30 months. Multivariate linear regression analysis shows that the one thing that prevents this from working is sugared beverage consumption. The more sugared beverages his patients drink, the less well the lifestyle interventions work.
Exercise does not work by burning calories. You'd have to jog 20 minutes to burn off one chocolate chip cookie. One Big Mac would require you to mountain bike for
Sugar and Fiber"When G-d made poison he packaged it with the antidote." Fructose is a poison, but it's packaged in fruit with lots of fiber. Sugarcane is a stick with so much fiber it's impossible to chew. Fruit is OK to eat because the fiber limits the amount of fructose you can take in, fiber is an essential nutrient that you need anyway, and you get various micronutrients that help your liver do its thing. Inhibiting the fructose uptake allows the bacteria in your colon to metabolize the fructose instead of your liver, which is why fiber causes gas. You have two choices: "fat or fart." Fiber makes your food reach your ileum faster, which raises PYY which tells your brain your stomach is full. And fiber prevents free fatty acids from being absorbed so that they reach the colon, are metabolized by bacteria into short chain fatty acids, which suppress insulin. That's why the paleolithic diet works - you eat the food as it comes out of the ground, so you get a lot of fiber.
Children and RegulationKids are at greatest risk because so many kids' foods and drinks are loaded with sucrose and HFCS. It's not just that the more sugar you expose children to, the more they crave it later - the more sugar a pregnant woman consumes, the more gets across the placenta and causes developmental programming and adiposity (extra fat) before the baby is even born. Beer and soda are metabolically equivalent - 150 calories, 90 of which are metabolized by the liver. Giving your kid a can of coke is just like giving your kid a Budweiser - same dosing, same mechanism, same reason. "Fructose is ethanol without the buzz."
The FDA ought to control fructose, because fructose is a toxin. It has toxic effects in the liver, but not immediately - after 1000 meals, not just 1 meal. The FDA doesn't do this because of political and economic pressure - food is one of America's primary exports, corn especially, and we can't have the FDA saying that our food is toxic. The government is unlikely to do anything, so it's up to us to make ourselves aware of this.
Although I've changed my mind about sugar this doesn't mean I agree with everyone who's been demonizing carbs or HFCS. If Dr. Lustig is right, "low-carb diets" are missing the point. Bread, pasta, and other starches are fine since starch is a glucose
My ThoughtsI'm going to have a really hard time following my own advice. I have a huge sweet tooth, and I enjoy tiki drinks which have a lot of sugar and ethanol which are doubly bad for my liver. On the other hand I don't drink beer, I've cut down significantly on my soda consumption, I drink sugarless soft drinks when I do, and I've stopped drinking lemonade. I've started drinking tea that tastes good without sugar, and having regular tea and coffee with either less sugar or with a reduced mix of sugar and artificial sweetener.
(There's a whole other can of worms talking about the difference between sucralose, aspartame, and saccharin, which I might write about later when I figure out more.)
Update: a counterpoint that I don't find particularly persuasive but is worth mentioning