August 14, 2023
Here is a short written version of the fructose story in tandem with the podcast with Dr. Rick Johnson where we go deep. We are going to discuss the survival switch and fructose metabolism in specific as it relates to pregnancy. It will be another life changing discussion for many of us.
Fructose is the natural sugar found in fruit, honey and root vegetables. Historically, humans consumed fructose in these natural whole foods and did so moderately. Since the 1970's, there has been a major rise in fructose consumption, primarily as a beverage. We are consuming it daily in fruit juices and sweetened drinks like soda, energy drinks and sports drinks. The advent of government subsidized high fructose corn syrup (HFCS) has provided companies a very cheap source of processed sugar to sweeten beverages and processed foods. Cheap and sweet. Not a good combination for humans. Fructose is much sweeter than glucose making it the driver of most sweet foods taste. From the 2010 National Health and Nutrition Examination Survey, we observe data that Americans consumed around 24 grams of fructose per day in the 1970's. Now that number is in the 55 gram per day range. Adolescents take the prize at 70+ grams a day. This is equal to 17+ teaspoons (packets of sugar) a day!!!!! This is a bolus of calories, but this is not the whole story.
Why does it matter?
Because it is driving metabolic disease in most Americans costing us all countless healthcare dollars and lost healthy days of life. The newest data by Dr. Johnson points to the fructose problem driving perinatal complications. Let's go back to the fructose story.
The story:
One major factor in the perinatal preeclampsia problem in the United States is the constant and excessive exposure to the monosaccharide fructose and the disaccharide sucrose which is a combination of one molecule of glucose and one of fructose in something that we call table white sugar.
How does the body see fructose?
The liver is the location for the metabolism of most of the fructose whereas glucose is metabolized everywhere especially the muscles and the brain. The majority of ingested fructose goes to the liver where it is metabolized to fat without the control of the hormone insulin and feedback negative regulation. This is not good. The body likes to control the metabolic system through feedback loops that shut off when calorie/sugar/fat contents are sufficient.
Fructose directly turns on genes that increase fat deposition! Why would this be??? Let us look at gorillas. They gorge on fruit during the natural fruit season in the fall in order to produce fat for the long winter. This is sort of like a polar bear gorging on seals in the fall to survive the winter. Nature has a plan. Where does it go wrong?
Humans!
We take seasonal fruit and give access to them year round. We make juice and demand that children get juice or milk in school when water is the best choice. We make HFCS cheap and accessible all year long in soda and beverages. Oops. We have just produced a mismatch of our genetically perceived environment and the true environment. We have a genetically predisposed seasonal fruit metabolism style with fructose exposure all year long. This also happens through any excessive fructose ingestion as foods, beverages or even starches through a reverse fructose engineering called the polyol pathway.
(Part of the Science: Fructose also causes a decrease in the enzyme lipoprotein lipase, which keeps fat particles in the blood circulation. Fructose also has an effect on increasing the transcription of genes that promote glucose production in the liver and thus more glucose release. The end result is excess blood sugar, the development of insulin resistance, type II diabetes mellitus and leptin resistance. The science gets much deeper.)
So, fructose used to be useful during periods of feast and famine. What used to be helpful is now dangerous with constant exposure. Nature always has a plan.
Let's read the abstract from Dr. Johnson's recent paper in the journal Nature Hypertension Research: "Preeclampsia is a hypertensive disorder of pregnancy and is due to abnormal placentation. The pathogenesis remains unclear. Fructose is biologically distinct from glucose and has a critical role in fetal growth in early pregnancy. Many species, including humans, produce fructose in their placenta during the first trimester to assist fetal growth and survival during a time when hypoxia is significant. Fructose is preferred over glucose in hypoxic tissues, and in the developing fetus, fructose has a critical role in stimulating the production of nucleic acids, lipids and glycosaminoglycans. Fructose production normally decreases significantly following the establishment of maternal-fetal circulation following placentation. However, if there is impaired placentation, local hypoxia will continue to drive fructose production. Excessive fructose metabolism drives endothelial dysfunction, oxidative stress, elevated blood pressure, insulin resistance, fatty liver, and a rise in uric acid and vasopressin levels, all of which are features of the preeclamptic state. In addition to fructose production, dietary fructose, for example, from soft drinks, would be additive and has been reported to be a strong independent risk factor for preeclampsia. Uric acid-associated endothelial dysfunction disturbs the invasion of the spiral artery, leading to placental ischemia and further placental hypoxia." (Nakagawa et. al. 2022)
This abstract is again a look at the upstream anthropological biology of human survival being suited for a normal environment where the placenta has a specific plan during early embryology. The placenta has a poor blood supply for 8 plus weeks after the sperm and egg unite. That issue was solved thousands of years ago by the placenta's cells choosing to metabolize fructose primarily via glycolysis (where oxygen is not required) leading to the energy requirements being fulfilled in this low oxygen state. As Dr. Johnson notes, when the blood supply to the placenta takes hold, the energy supply switches to glucose metabolism with oxygen which is more energy producing and promotes rapid growth. However, it appears that the consumption of fructose via mothers and or the consumption of high volume starchy foods is driving the metabolism of fructose via two different pathways leading to the same end result, decreased fetal placental circulation development which in turn leads to endothelial dysfunction, oxidative stress (rusting for humans), increased blood pressure, insulin resistance and excessive fat deposition all of which trigger a metabolic syndrome like event that we call
preeclampsia. The end product of fructose metabolism following ingestion or internal generation via the polyol pathway is the production of uric acid. This molecule is at the center of all of the dysfunction and it is the reason that we have to counsel pregnant women to avoid excess ingestion of foods and beverages made from fructose, sucrose and starch.
So, what do we do?
The first thing to do is to reduce and preferably eliminate sugar-laden beverages including juice. Get soda, juices, coffee beverages or sports drinks out of the house. Drink mostly water or unsweetened teas.
Second, reduce how fast the sugar is absorbed by adding fiber to your diet. The best based sources of fiber are sweet potatoes, vegetables, beans and whole fruit as berries. Adding fiber to every meal is a brilliant idea to reduce blood sugar spikes.
Third, exercise more to burn sugar so that it can't be used to make fat. This also turns on more glucose transporters to push glucose into the muscle which decreases the amount that the liver sees thus decreasing fructose production via the polyol pathway.
Fourth, increase the intake of bright colored vegetables and fruits, which contain natural chemicals to reduce the burden of ROS. Spices, dark chocolate, nuts and berries have very high ORAC (Antioxidant strength) scores.
Fifth, read labels and avoid foods with fructose or HFCS in them.
Sixth, drink lots of water when you eat anything salty to reduce the sodium concentration in the blood which decreases the polyol pathway activation and thus fructose production with all of its downstream effects.
My take home point today: Fruit is ok in moderation, sugar drinks are not!
Listen to the podcast to get a deeper perspective directly from Dr. Johnson.
Dr. M
For more information on this topic, visit: https://drrichardjohnson.com
