Robert Lustig derives the title of his book from the terms ‘metabolic’ and ‘diabolical’. The 2020s are the era of conspiracy theory. He claims that Americans are victims of a vast commercial conspiracy

• Modern medicine is not interested in making us well as it treats only symptoms and not the disease,
• Doctors need to learn that nutrition is about biochemistry and NOT about nutrients,
• Dietitians believe in calories, a discredited concept, and endorse processed foods,
• Dentists give out candy as treats to their young clients to promote tooth decay,
• Big Pharma taught them everything they know because they push drugs on us to treat our symptoms, and
• USDA and FDA don’t kill us; they wait for us to die.

And where does Big Food come in? It processes ‘real’ food to make it toxic and addictive. Then it reaps huge profits as we become ill and die. Lustig declares altered metabolism as the real disease. Medicine fails to treat it and nutrition fails to appreciate it.

Lustig’s main message is that we need to “protect the liver, feed the gut.” He proclaims that food processing robs ‘real’ food. Processed food fails to protect the liver, feed the gut or both. Lowered life expectancy in America supports his premise. What are his qualifications for this assault on medicine, nutrition, and processed food? He practiced pediatric neuroendocrinology for over 30 years. His undergraduate major at MIT was in Nutrition and Food Science. The emphasis of his studies was nutritional biochemistry.

A biochemical mechanism. In previous posts I called for a mechanism linking ultra-processed food to disease. Many of these chronic diseases result from metabolic dysfunction. The likelihood of finding a universal mechanism is slim. No consistent link exists between this array of ultra-processed products and disease. Lustig presents a mechanism linking fructose to eight vulnerable intracellular processes. It is an elegant mechanism, like one mentioned in an earlier post. It is yet unproven, but that is how science works. His ideas are not accepted science. I understand. My ideas are not accepted science either.

Metabolic dysfunction. To Lustig medicine and nutrition converge in biochemistry at the cellular level. I appreciate that. He describes eight intracellular processes that can go wrong:

1. Glycation—browning reactions in our cells,

2. Oxidative stress—degradation of membranes in and around each cell,

3. Mitochondrial dysfunction—affects the ability to use energy,

4. Insulin resistance—lowers the body’s ability to clear glucose in the blood,

5. Membrane integrity—leakage and failure to maintain cellular functions,

6. Inflammation—failure to respond to external challenge,

7. Epigenetics—inappropriate firing or silencing of gene response,

8. Autophagy—inability to clear out biological waste.

We tend to think of malfunction of these processes as chronic diseases. Obesity is now also considered a chronic disease by the medical community. Lustig views each of these conditions as symptoms of the real disease. Metabolic dysfunction is the disease we should be treating. He considers metabolic abuse as a cause of premature aging. Our focus in metabolic health, he states, is attention at the cellular level. Up to this point I am in general agreement, but there is a nagging concern.

My doctoral dissertation looked at oxidation of membrane lipids (fats) in flounder muscle. Upon graduation, I  studied lipid oxidation of membranes in fruit and vegetable disorders. Some of that work relates to plant senescence. Plant scientists think of plant senescence as programmed death. After harvest, fruits and vegetables continue to act as living organisms. An understanding of postharvest physiology leads to handling conditions that slow senescence.

Postharvest technologists extend shelf life through optimal harvesting techniques and decay prevention. Temperature management. controlled-atmosphere storage, and other technological tricks help slow senescence. We can even use some of these technological techniques at home. Despite all this attention the fresh fruit or vegetable experiences death. One may be dying in the back of a home refrigerator now. Is metabolic dysfunction like plant senescence? I don’t know. Plant cells do not experience insulin resistance or inflammation. All other intercellular processes listed earlier are characteristics of plant senescence. Both processes are more like than different from each other. My questions then are

• Is metabolic dysfunction a form of preprogrammed death in animals?
• Or is senescence the disease in plants with intracellular symptoms of metabolic dysfunction?

What is wrong with nutrition research? Nutrition research is almost useless to the author for two reasons. First it is correlational and not conclusive. Second, it relies on nutritional epidemiology featuring consumer recalls of foods eaten. How accurate is that? Lustig and I agree on correlation studies which may or may not be definitive. Such studies form the basis for online stories that condemn ultra-processed foods. Nutritional epidemiology is an unfortunate cost of doing research. Yet, there are key pieces of information that we are unable to get any other way. The author ignores the nutritional biochemistry studies of food during human digestion.

What does processing do to a food? Throughout the book the author promises to tell us what processing does to our foods. We don’t learn as much as promised. We do learn that during processing

• Dangerous chemicals form. Metabolical presents trans fats, PAHs, AGEs and 3-MCPD. We learn that we can form trans fats in the kitchen when we exceed the smoke point during frying. FDA disallowed trans fats in processed foods in the USA in 2018. Polycyclic hydrocarbons (PAHs) come from grilling. Backyard barbeques are much more dangerous than processed foods from PAHs. Advanced Glycation End products (AGEs) are due to Maillard browning. Anytime a food processor or home cook browns food, AGEs form. One specific AGE, acrylamide, has attracted attention. It appears when browning meat or making French fries. A GMO potato features much lower levels of acrylamide in our fries. Which is more dangerous a GMO potato or acrylamide? 3-monochloropropanediol (3-MCPD) forms during flash heating. 3-MCPD results from a free fatty acid encountering the Cl^– in salt during flash heating. It is a molecule that bears further study.
• Good stuff disappears. The guilty processes are milling and juicing. The author worries about loss of dietary fiber. We like our bread white and our juices without pulp.  Lustig is right that many products labeled as whole grain are not good sources of dietary fiber. He also notes that we need both soluble and insoluble fiber. There are high-fiber breads and breakfast cereals for sale. Nutritional labels of these products show us how much fiber is present. We can make up the fiber deficit by eating fresh produce and whole grains, like buckwheat groats.
• Preservatives appear. Lustig makes his point with the 20-year-old Twinkie and 10-year-old McDonald’s cheeseburger. Are popular YouTube myths necessary for his argument? Preservatives listed include three antioxidants, nitrates and nitrites, trans fats, and sugar. Antioxidants keep products from going rancid and protect us from oxidized fats. Nitrates and nitrites are some of the oldest forms of preservatives. Cured meats pose a risk, but are we willing to give up bacon, pepperoni, and pastrami? Curing meats with celery salts to get natural nitrates is deceptive. Natural nitrates from celery are as hazardous as added ones. Trans fats are not a preservative and are no longer with us. Pointing out a disgraced, discontinued additive must be too tempting to ignore. Salt and sugar are the two most used preservatives in processed and homemade foods.  Processed foods don’t spoil as fast as ‘real’ foods. In an era where we try to prevent food waste, preservatives don’t seem to be such a bad deal.
• Properties of foods change. The author directs his attention to formation of addictive substances. Alcohol, caffeine, and sugar are the three he mentions. Alcohol is a Substance Use Disorder as recognized by DSM 5. Caffeine and sugar are not SUDs. Every food process in a processing plant or the restaurant or at home alters properties of raw foods. Fermentation is a major modifier of food properties. Chopping, heating, drying, freezing etc. also alter appearance, texture and flavor of foods. That is what food processing and culinary preparation are all about.

Metabolical introduces seven engineering criteria make processed food toxic. Processed foods are mass produced and consistent in different batches and countries. Processing uses specialty ingredients such as emulsifiers. Most important of all, processed foods must have a long shelf life. Where is the connection to metabolic dysfunction? Where are the data? On what basis can we draw the conclusion that these criteria make food toxic? The book concludes with a 135-page rant on the evils of processed food. On what basis does Lustig draw his conclusions? He refers to correlational studies that do not show causation. He also relies on those based on nutritional epidemiology. I thought that is why he rejects nutritional research. The biochemistry of fructose metabolism is intriguing. He follows with the same unfounded accusations advanced by Bittman, Pollan, and others. I found too much heat and too little light. He does not make his case against processed food beyond fructose.

Bottom line. Lustig’s mechanism for fructose and sugar-sweetened foods and beverages deserves more funding. Take some grant money supporting food addiction and ultra-processed food research. Separate out high-sugar products from other ultra-processed foods in the correlational studies. Include high-sugar items like cakes, cookies, and brownies made in the home. It is strange that the author defends honey while savaging high-fructose corn syrup. The ratio of fructose to glucose in each ingredient is similar.

Do I buy the concept that we are living a vast commercial conspiracy? Do doctors not understand medicine and dietitians not understand ‘real’ nutrition? Are Big Pharma and Big Food killing us while FDA and USDA sit around to watch us die? No, I’m not that into conspiracy theories. Are processed foods hazardous to our health? Some can be if we eat too much food and too much of the wrong kind of foods. Even Lustig advises moderation when grilling out. To me, grilled foods are the most dangerous foods we consume, and moderation here is not a good thing.

I did not respond to the author’s claim that processed food causes a decline in life expectancy? I will write about that next week.

Next week: Contribution of processed foods to lowered life expectancies?