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  • Between 1851 and 1930 there were no more than about 50 reported cases of age-related macular degeneration (AMD) in the medical literature. As of 2020, an estimated 196 million people worldwide have AMD
  • There’s compelling evidence that AMD is not caused by aging or genetics but by processed foods
  • The four toxic ingredients in processed foods causing a majority of chronic health problems are refined wheat flour, refined added sugars, polyunsaturated vegetable oils and trans fats
  • Processed foods cause mitochondrial dysfunction, which in turn leads to chronic diseases of all kinds, including Type 2 diabetes, heart disease, cancer and AMD
  • Excessive consumption of processed vegetable oils results in the oxidation and breakdown of omega-6 into toxic aldehydes. This damaging peroxidation cascade damages cardiolipin, a phospholipid in your mitochondria, resulting in mitochondrial dysfunction

Dr. Mercola Interviews the Experts

This article is part of a weekly series in which Dr. Mercola interviews various experts on a variety of health issues. To see more expert interviews, click here.

In this interview, Dr. Chris Knobbe, an ophthalmologist, discusses some of the eye-opening information found in his book, “Ancestral Dietary Strategy to Prevent and Treat Macular Degeneration.”1

Knobbe is the founder and president of the Cure AMD Foundation, a nonprofit dedicated to the prevention of age-related macular degeneration (AMD), which is the No. 1 cause of blindness among the elderly. His book is a comprehensive treatise on the historical progression of AMD and provides compelling evidence that this is a disease caused by processed foods.

“It is manmade, processed, nutrient-deficient and toxic foods that are driving all the chronic diseases,” he says. “They're driving heart disease, stroke, hypertension, cancer, metabolic syndrome, obesity [and] macular degeneration …

When I say processed, manmade, nutrient-deficient, toxic, or processed foods, that is really just four things. It's really fairly simple. It's the nutrient-deficient foods which are refined: Wheat flour, refined added sugars, polyunsaturated vegetable oils and trans fats.”

Although we did not discuss these dietary issues and its connection to COVID-19 risk because the interview was done before March, it is still very relevant. We now know that eating processed foods, especially vegetable oils, will increase insulin resistance and metabolic inflexibility, which is one of the two largest risk factors for COVID-19, the other being vitamin D insufficiency.

Vegetable Oils Responsible for Emergence of Heart Disease

Refined flour, sugar, trans fats and vegetable oils are relatively recent additions to our food supply. Refined sugar has been around for a few hundred years, but it was consumed in really low amounts until the late 19th century. Vegetable oils emerged after the American Civil War. Refined white wheat flour came about in 1880 and trans fats in 1911.

“Those foods are what is driving almost all of our chronic metabolic and degenerative diseases,” Knobbe says. “Over the past year or two, I really dug into the history of most of these chronic diseases. For example, heart disease was an extreme medical rarity in the 19th century.

We have data from a paper by Jones and colleagues [published] in 2011. What they showed was that in the town of Boston in 1811, there were no known heart attacks.

Only 2.6% of that population in Boston died of sudden death. So even if we thought every single one of those was heart disease, which they weren't, but even if you wanted to say that they were, it's only 2.6% …

Sir William Osler, a famed physician, was one of the founding members of Johns Hopkins Medical Center. In 1897, he published a paper in which he reviewed his previous 21 years of hospital experience, and he noted maybe around a half a dozen cases of angina — chest pain that might be related to heart disease — but not a single myocardial infarction, not a single heart attack.

Some 13 years later, in 1910, he recounted 208 additional cases of angina, which he attributed to the stress of modern day life. In 1900, from the Jones paper, heart disease accounted for 12.5% of deaths, but that was known not to be coronary artery disease … That was cardiac valvular disease, which is driven by infectious diseases like rheumatic fever, syphilis and endocarditis. It wasn't heart attacks.

In fact, 1912, James Herrick published a paper on the first known heart attack in the United States with documented autopsy evidence. What's staggering is that 30 years later, in the 1930s, heart disease became the leading cause of death. It was virtually unknown in 1900. Nobody knew what a heart attack was in 1900. Nobody had seen one …

By 2010, 32.3% of people in the United States are dying of heart disease. But if you go back, what we're going to notice is that vegetable oils and trans fats, margarines, those things were replacing animal fats. That is the major driver of this, I believe.”

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Diet Has Increased Cancer and Diabetes

Knobbe also reviews the historical data on cancer. Of the 942 people who died during 1811 in Boston, only five died of cancer. That’s 1 in 188 deaths. By 1900, cancer killed 1 in 17 people. Today, cancer accounts for 31.2% of deaths in the U.S., or nearly 1 in 3.

The same exponential growth can be seen in Type 2 diabetes. In the 19th century, any form of diabetes was extremely rare. One of the first studies on diabetes was published in 1935. In 1935-1936, 0.37% of Americans had diabetes. By 2015, that rate had risen to 9.4%. That's a 25-fold increase in 80 years.

The situation may actually be even worse than that, though, as the 9.4% rate refers to documented full-blown clinical diabetes. If you add in prediabetes and insulin resistance, then nearly 9 in 10 Americans are affected. According to recent NHANES data,2 87.8% of Americans are unhealthy based on five parameters of metabolic health, so virtually the entire population is at risk for and headed toward Type 2 diabetes.

Shocking Rise in AMD Prevalence

Macular degeneration became discoverable following the invention of the ophthalmoscope in 1851. The ophthalmoscope was in broad use by 1880. By 1900, there was 140 versions available. By 1914, there was over 200 versions of ophthalmoscope in use around the world.

Yet, between 1851 and 1930, there were no more than 50 cases of AMD reported in all the world's medical literature. It was virtually unknown. Prevalence began to increase in the 1930s, and by 1975, an estimated 4.5 million Americans suddenly had macular degeneration. By 1994, 15 million had it, and as of 2020, estimates put worldwide prevalence at 196 million. In 20 more years, it’s expected to hit 288 million.

“I've done the same thing with metabolic syndrome and with myopia, nearsightedness. They all track essentially the same. We see all of these go from rarity in the 19th century and early 20th century to staggering numbers today, and the prevalence continues to increase,” Knobbe says.

Metabolic Dysfunction Is Common Denominator

The common denominator that all of these diseases share is mitochondrial dysfunction caused by processed foods. Hopefully, knowing this will inspire and motivate you to change your eating habits. Once you realize what these foods are doing to you at the molecular level, you’ll be more excited about healthy choices.

“As I mentioned, what's happened is we have replaced nutrient-dense, healthy, safe, organic foods with nutrient-deficient, toxic, dangerous ultra-processed foods. As of 2009, 63% of the American diet was made up of those four foods — added sugars, refined white wheat flour, vegetable oils and trans fats …

In the year 1900, when everybody was healthy, 99% of added fats in the diet were animal fat — lard, butter and beef tallow. But by 2005, 105 years later, 86% of the added fats in the diet of Americans are vegetable oil-derived. They include vegetable oils, margarine [and] butter substitutes. Ultimately, all of those come from these dangerous vegetable oils that don't provide healthy fat-soluble vitamins, and are extraordinarily toxic.

What we now understand is that it is mitochondrial dysfunction that ties together all of these chronic diseases — heart disease, cancer, stroke, hypertension, obesity, metabolic syndrome, macular degeneration …

When you consume a whole lot of these edible seed oils, vegetable oils or omega-6 — that's all the same thing — then those oils, those omega-6s, oxidize and break down into toxic aldehydes. So, when we try to metabolize these, when we try to burn these for fuel, or we store them, what happens is they create a catastrophic peroxidation cascade.

They cause oxidation in fats, proteins [and] carbohydrates in your cells and cellular membranes everywhere. Ultimately, what this does is it damages a molecule called cardiolipin … a phospholipid in your mitochondria. It's a scaffold upon which the electron transport chain of your mitochondria depends. When cardiolipin is altered … it damages it.

What happens is that the mitochondria are no longer able to hold a proton gradient. They lose that proton gradient, and this causes loss of energy. The mitochondria then become sick; they’re not producing energy properly. Well, without energy, everything begins to fail. One of the first things that happen is that you can't properly burn fats for fuel, and you become more carbohydrate-dependent.”

The cardiolipin is only found in the inner mitochondrial membrane. In the lecture above, Knobbe illustrates the chain of events that result in mitochondrial dysfunction.

High-PUFA Diet Triggers Catastrophic Peroxidation Cascade

Paradoxically, the cardiolipin molecule depends on linoleic acid, and linoleic acid is the primary omega-6 in our diets. However, in a high-linoleic acid diet, the linoleic acid in the cardiolipin molecule ends up being destroyed. So, what gives? Knobbe explains:

“When you're consuming a high-PUFA diet, it's like having a house full of little tiny papers, and when you're welding or something, sparks are flying. You're going to catch the house on fire when you consume all these vegetable oils because you're going to be filling up your fat cells, tissues and membranes with linoleic acid, these omega-6s, and they're very fragile.

You're going to start this catastrophic peroxidation cascade, and you're also going to destroy the linoleic acid in the cardiolipin molecules where it is critical. Subsequently, you lose energy in your mitochondria, make your mitochondria sick, and then you become sick. This is how we become tired, fatigued, and we're gaining weight all at the same time.

I think most people are interested in how to lose weight. But by far, a million times more important is to be healthy, and this is how we get healthy. The same things that make you healthy also make you leaner.”

Another important variable here is the influence of carnosine, a dipeptide — two amino acids put together — made up of beta-alanine and histidine. Carnosine is only found animal products. It serves as a scavenger or sink for reactive carbonyl groups, intermediaries that go on to form advanced lipoxidation end-products and emulsification end-products.

If you can grab these carbonyls before they attack proteins and fats, you can essentially stop the vicious cycle resulting in catastrophic peroxidation. This is yet another reason why I do not recommend diets that exclude animal products and meat, as they will lower your carnosine level, and carnosine is a really important nutrient to limit the damage from oxidation products. It's also important for mitochondrial function.

Toxic Aldehydes

Knobbe has been studying the toxic aldehydes that result from these omega-6 fats. When you consume an omega-6 fat, it first reacts with a hydroxyl radical or peroxide radical, producing a lipid hydroperoxide. This lipid hydroperoxide then rapidly degenerates into toxic aldehydes, of which there are many.

Examples include 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA), as well as oxidized linoleic acid metabolites such as 9-HODE, 13-HODE, carboxyethylpyrrole and acrolein.

“Most of my research in terms of what these do is focused on what's going on in the eye,” Knobbe says, “but these are extraordinarily dangerous molecules. For example, HNE has been tied to virtually every single chronic disease there is, including heart disease, atherosclerotic disease, Alzheimer's, macular degeneration, obesity, Type 2 diabetes.

All of those have been connected to HNE, and it’s been called a causal factor. It is that powerful. These are extraordinarily dangerous molecules at very low concentrations. MDA is an extreme toxin. It’s cytotoxic. It is mutagenic. It's carcinogenic.

The oxidized linoleic acid metabolites, like the 9- and 13-HODE, they are driving oxidized LDL, for example, which is a huge player in atherosclerosis. Carboxyethylpyrrole, in the eye, induces autoantibodies … They attack the retina directly. We see these more than double the numbers in people with macular degeneration. So, we have a major driver there.

Acrolein is the toxic aldehyde that is in cigarette smoke and vegetable oils. To give you an idea, an average cigarette produces 18 to 98 micrograms of acrolein when you smoke it. A large french fries, roughly, 154 grams of french fries from a fast food restaurant … produce 1 to 1.5 milligrams of acrolein.

So, let me put this in perspective. Eating a large french fries can give you the same amount of acrolein as smoking 17 to 26 average cigarettes or up to 83 cigarettes lowest in acrolein. Now, they both can cause lung cancer, for example.

Here we can see that you're getting a much larger dose of acrolein from eating french fries than you're ever going to get from even being near smoke.”

Knobbe also points out what you lose out on when eating vegetable oils, namely fat-soluble vitamins. Animal fats such as lard, butter and beef tallow provide not only healthy fats but also essential vitamins such as vitamins A, D and K2. “Let's face it, meat is the most densely nutritious food that most anybody in the United States ever gets,” Knobbe says.

One of the benefits of eating meat is that it is loaded with carnosine, which is a dipeptide consisting of beta-alanine and histidine. This is a terrific scavenging agent for advanced lipoxidation endproducts (ALEs) like the fats discussed above.

If you’re excluding meat from your diet and consume large amounts of industrial processed oils, you’re setting yourself up for metabolic disaster. Without a doubt, low carnosine and high aldehydes is a prescription for premature death from chronic disease. At the very least it would be wise to take a carnosine or beta-alanine supplement.

Your Body Can Recover

While the good news is that you can recover your health by eliminating these unhealthy omega-6-rich oils from your diet — essentially ditching processed foods — the bad news is they have a rather long half-life.

According to Knobbe, polyunsaturated fats from vegetable oils, seed oils and trans fats are mostly stored (opposed to being used for fuel), and have a half-life of 600 to 680 days. That means it will take quite a few years to empty your body stores of these damaging omega-6 fats.

“I quit consuming these fats in 2011,” Knobbe says, “and I think it was 2015 or 2016 before I started hitting a lot better health. But now, at age 59, I can weightlift, sprint, run stairs.

I do so many of the things I could do when I was in my 20s. I wasn't headed that way back in 2011. I was headed for absolute disaster. I mean, I may have not even been alive today if it weren't for beginning to understand all this and changing my diet.”

In the interview, Knobbe also discusses how his arthritis was traced back to oxalates, which are found exclusively in plants. Ironically, many of the plant foods that are praised for their healthiness have the highest amounts of oxalates and can wreak havoc on those with arthritis or other autoimmune conditions.

“Oxalates can precipitate out in your joints, tendons, muscles, perhaps arteries and drive all sorts of chronic inflammation, so arthritis, myalgias, chronic fatigue syndrome, fibromyalgia, all of these disorders may be driven by oxalates,” he says.

“In 2011, when I was 50 years old, my arthritis was so severe. I was in a devastated condition … [Dr. Mercola] referred me to Sally K. Norton, who is perhaps the world's expert in this area. I’m now … changing my diet to get lower in oxalates, and I'm doing better and better all the time. I really believe that it may not be long before I am arthritis-free …

I think I would eat 1 or 2 cups of spinach in salads three or four times a week. That’s massive doses [of oxalates]. Most people shouldn't get more than 150 milligrams of oxalates in a day. Many days, I would be getting 1 to 1.5 grams, so maybe about 10 times as much as what's recommended.

Over decades, you accumulate these [oxalates]. They're stored in your tissues. The good news is that they're water soluble, and they can leach back out, but it too can take years. So, I'm apparently on a slow recovery, kind of like getting rid of polyunsaturated oils in your body. It'll happen, but it's not going to happen overnight.”

Macular Degeneration Strongly Linked to Processed Food Diet

Aside from improving your overall health and avoiding chronic diseases like Type 2 diabetes and heart disease, avoiding sugars, refined wheat flour, vegetable oils and trans fats is also crucial for the prevention of AMD. Knobbe reviews research showing the connections between a processed food diet and AMD.

In Southwestern rural Nigeria, 0.1% of the adult population over the age of 50 have macular degeneration. A mere 240 miles away in Onitsha, Nigeria, the prevalence is 3.2%. The difference between these two populations is their food supply.

The people in Southwestern rural Nigeria do not have access to processed foods. They live off native traditional foods. The people in Onitsha, Nigeria, do have access to processed foods, but at far lower amounts than what we get in the U.S.

Barbados, meanwhile, has a macular degeneration rate of 24.3% — 243 times higher than the Africans of Southwestern rural Nigeria. What stands out about Barbados is the fact that it’s known by nutrition researchers all around the world as a Mecca for processed food. They import almost all of their food.

“You and I know what that means. It means it's all sugar, refined flour and vegetable oils. That's what you can package up and send across continents, people can eat it months later, and it's still called food,” Knobbe says.

“That's what these people are eating, and they have a ‘world profile’ of metabolic disease in Barbados, metabolic syndrome, obesity, heart disease, cancer, Type 2 diabetes and 24.3% macular degeneration prevalence — 243 times greater than the Africans of Southwestern rural Nigeria who can't get processed foods.

All three [populations have] the same West African heritage. How could we in any possible way conclude that that's about aging and genetics, which is the primary belief system about macular degeneration today?

… Similarly, in 1969, New Zealand’s macular degeneration prevalence for people over 50 was 1.3%. In 2014, macular degeneration prevalence in people over the age of 45 was 10.3%. That's an eight-fold increase …

Their vegetable oil [intake] in 1960 was less than 1 gram a day. By 1991 onward, it was around 20 grams a day. So again, we see a huge increase in vegetable oils, and we see a massive increase in macular degeneration prevalence.”

More Information

To learn more about how your diet influences your risk of AMD and other chronic diseases, be sure to pick up a copy of Knobbe’s book, “Ancestral Dietary Strategy to Prevent and Treat Macular Degeneration.” More information can also be found on

“If you want to reach out to me, you can go to the contact link for that and send me a message. I answer every single message,” Knobbe says. “I'm in this to help people, and I love it.”