#87 - Rick Johnson, M.D.: Fructose—The common link in high blood pressure, insulin resistance, T2D, & obesity?
Jan 6, 2020
auto_awesome
Rick Johnson, a Professor of Nephrology at the University of Colorado, dives deep into the surprising effects of fructose on metabolic health. He reveals how fructose metabolizes differently than glucose, contributing to weight gain and insulin resistance. Johnson explains the alarming connection between fructose and high blood pressure, as well as its link to conditions like fatty liver and diabetes. He also shares insights on uric acid levels and the potential benefits of fructokinase inhibitors, challenging common beliefs about sugar and artificial sweeteners.
Fructose metabolism leads to the generation of uric acid, causing high blood pressure and metabolic disorders.
An ancient uricase mutation in apes enabled fat storage, survival during food scarcity, and the passing on of this mutation to humans.
High uric acid levels from fructose metabolism deplete intracellular phosphate, trigger AMPD pathway, and lead to obesity, fatty liver, and elevated blood pressure.
Fructose metabolism causes ATP depletion, inhibits fat oxidation, promotes fat synthesis, contributes to fatty liver, oxidative stress, and insulin resistance.
Deep dives
Fructose Metabolism and High Blood Pressure
Fructose metabolism and its impact on high blood pressure were explored in this podcast episode. The speaker discussed how fructose, when metabolized, leads to the generation of uric acid, which can cause high blood pressure. Studies on animals showed that a high salt diet increased serum sodium, which activated an enzyme converting glucose to fructose. This fructose metabolism resulted in elevated blood pressure. However, when the metabolism of fructose was inhibited, the rise in blood pressure was blocked. It was also found that sugar, particularly in the form of fructose, raises uric acid levels, contributing to the development of obesity, insulin resistance, fatty liver, and elevated triglycerides. The episode emphasized the significance of fructose and its connection to high blood pressure and metabolic disorders.
The Evolutionary Impact of a Uricase Mutation
The podcast delved into the fascinating evolutionary impact of a uricase mutation that allowed certain apes to efficiently store fat during periods of food scarcity. This mutation, which occurred about 12 to 15 million years ago, increased the uric acid response to fructose and facilitated fat storage. It enabled the survival of apes in Europe during a period of global cooling and ultimately allowed them to make their way back to Africa, passing on the uricase mutation to their descendants. Humans and primates with this mutation have a unique ability to toggle between metabolic pathways, allowing for fat storage and energy conservation. The uric acid generated during fructose metabolism plays a critical role in this process.
Uric Acid, Gout, and Metabolic Dysfunction
The podcast explored the multifaceted relationship between uric acid, gout, and metabolic dysfunction. It was noted that high uric acid levels are associated with increased risk of gout, a painful inflammatory condition. Sugar consumption, particularly fructose, was linked to elevated uric acid levels. The podcast discussed how fructose metabolism causes a depletion of intracellular phosphate and triggers an AMPD pathway, leading to metabolic effects such as obesity, insulin resistance, fatty liver, and elevated blood pressure. The phenomenon of fructose metabolism leading to these metabolic disorders aligns with the characteristics of metabolic syndrome. Additionally, the podcast highlighted that sugar consumption is more likely to cause obesity when consumed in liquid form due to the concentration and speed of absorption.
Fructose, ATP Depletion, and Metabolic Effects
The episode delved into the fascinating mechanism behind the metabolic effects of fructose and ATP depletion. The metabolism of fructose, unlike glucose, leads to a significant drop in ATP levels within cells, triggering a series of reactions. This ATP depletion pathway, coupled with increased lactate production and oxidative stress to the mitochondria, inhibits fat oxidation, promotes fat synthesis, and contributes to fatty liver development. Fructose metabolism also leads to oxidative stress in pancreatic islet cells, promoting insulin resistance. The podcast highlighted the adverse impact of uric acid on the islet cells and underscored how high sugar diets, even with calorie restriction, can lead to fatty liver, hypertension, insulin resistance, and other metabolic effects.
The Negative Effects of Excessive Sugar Consumption
Consuming high amounts of sugar, especially fructose, can lead to various health problems. Research shows that high sugar intake can cause fatty liver, diabetes, insulin resistance, and low-grade inflammation in the body. Even in small doses, fructose can have detrimental effects on metabolism and overall health.
The Role of Uric Acid in Metabolic Diseases
Uric acid, which is produced when the body metabolizes fructose, plays a significant role in the development of metabolic diseases such as obesity, diabetes, and cardiovascular disease. High uric acid levels can impair fat oxidation, contribute to insulin resistance, and promote the growth of certain cancers.
The Impact of Umami Taste and MSG
Umami taste, characterized by a savory flavor, is enhanced by monosodium glutamate (MSG) and certain purines, including uric acid. Foods rich in umami, such as certain meats and soy products, may raise uric acid levels and potentially contribute to metabolic dysfunction and weight gain.
Guidelines for Fructose and Sugar Consumption
It is advisable to limit or avoid excessive fructose and sugar consumption. Restricting processed foods with added sugar, sugary beverages, fruit juices, and high-fructose corn syrup is crucial. Moderation is also recommended when consuming natural fruits, as they can still contribute to fructose intake. Water intake and awareness of overall carbohydrate consumption are important factors in maintaining a healthy diet.
In this episode, Rick Johnson, Professor of Nephrology at the University of Colorado, explains how his research into the causes of blood pressure resulted in a change of research direction to focus more on how fructose has such profound metabolic effects. Rick discusses the relationship between salt and high blood pressure, provides a masterclass into uric acid, and expertly reveals the mechanisms and pathways by which sugar (specifically fructose) can profoundly impact metabolic health. From there, he explains how he applies this information to real life patients, as well as touches on some of the most promising ideas around pharmacotherapy that are being developed in response to the epidemics of fatty liver, insulin resistance, diabetes, and obesity. Furthermore, Rick gives his take on artificial sweeteners compared to real sugar, discusses cancer’s affinity for fructose, and much more.
We discuss:
The connection between blood pressure and fructose that shifted Rick’s professional focus [4:00];
The relationship between salt and blood pressure (and the role of sugar) [5:45];
Defining fructose, glucose, and sugar [19:30];
An ancient mutation in apes that explains why humans turn fructose into fat so easily [23:00];
The problems with elevated uric acid levels, and what it tells us about how sugar causes disease [31:30];
How sugar causes obesity—explaining the difference in glucose vs. fructose metabolism and the critical pathway induced by fructose [40:00];
Why drinking sugar is worse than eating it [50:00];
Unique ability of sugar to drive oxidative stress to the mitochondria, insulin resistance, and diabetes [54:00];
Why cancer loves fructose [1:00:15];
The many areas of the body that can use fructose [1:05:00];
