The Reason Why White Table Sugar and also Fructose in Fruits are Bad for Cardiovascular and Metabolic Health?

 

In this blog post here I posted yesterday on cholesterol and heart disease there was a comment by Dr Mary Lee that reads (in pink)

https://scientificlogic.blogspot.com/2023/

Thank you, Dr Lim for your splendid article and explanation on why cholesterol is not the main cause of heart disease as all along we all thought, even among doctors, that cholesterol is the cause of heart disease, resulting in untold profits from statin drugs being prescribed unnecessary as you correctly said. I don’t encourage the use of statins myself as a doctor.  

Frankly I find your biochemical equations on the synthesis of cholesterol in the body difficult to follow. I wonder if other readers understand.

 You also mentioned Professor Dr John Yudkin who was your mentor at London University that sugar was the primary cause of coronary heart disease rather than saturated fats or cholesterol. I have heard and read about Professor John Yudkin who was very famous.  His findings on why sugar is deadly rocked the world and medical and scientific professions are now reviving very strongly among the medical communities.

But how does that work since fruits also contain a lot of sugar?  As a doctor, as with everyone else, I would have thought fruits are good for health and may also be heart protective as they are rich in antioxidants. How would you explain that?

Dr Mary Lee

Here’s my reply to her (in blue):

Thank you for your kind words, your opinion and your question Dr Lee

Let me try to explain why cane white sugar (sucrose) is more harmful than glucose or even the sugars in fruits.

 Kindly allow me to explain this in technical biochemical language. Please bear with me.  Later I shall then explain why I like to use simple layman’s language.

The metabolic pathways of glucose and fructose take different pathways upon entry into the cell. Glucose undergoes phosphorylation via hexokinase to form glucose-6-phosphate, initiating glycolysis.

 This pathway generates pyruvate, subsequently entering into the Kreb tricarboxylic acid (TCA) cycle for ATP production.

Conversely, fructose is also being phosphorylated by fructokinase, forming fructose-1-phosphate, which enters glycolysis downstream.

The unique metabolism of fructose contributes to distinct intermediates, such as dihydroxyacetone phosphate and glyceraldehyde-3-phosphate quite different from glucose. Furthermore, fructose metabolism culminates in the production of acetyl-CoA, influencing lipogenesis. This is the key entry into cholesterol synthesis.  This divergence underscores the nuanced impact of glucose and fructose on cellular energy homeostasis and metabolic outcomes.

I hope this divergence in metabolic pathways of glucose and fructose, although both are simple sugars as glucose and fructose found in sucrose (ordinary sugar) and also in fruits explains why sugars on hydrolysis and in digestion is harmful, not just in the aetiology of cardiovascular disease as explained by Professor Dr John Yudkin my very highly respected mentor.

Fructose in fruits and also in sucrose or ordinary table sugar is the root cause of all these metabolic syndromes such as hyperglycaemia and Type 1 diabetes, atherosclerosis, dyslipidemia, hypertension, cardiovascular diseases, fatty liver and liver diseases... etc for which there is no cure unless we are willing to change the ways we chose our foods for better protective nutrition by reducing sugar intake.  

Fruits though are health-protective as you said, but excessive intake are also very heath-damaging because of the presence of fructose (fruit sugar) that takes different metabolic pathways.

The pancreas where insulin is secreted by the alpha and beta cells is then unable to handle even glucose as it usually does, let alone fructose that is then diverted to the liver. This may damage even the liver into fatty liver, perhaps into liver cirrhosis.  

 Fructose or fruit sugar overloads the pancreas into degeneration till even blood glucose becomes out of control and diabetes mellitus sets in.

A good example was Steve Jobs who died of pancreatic cancer because he only ate fruits and nothing else in his skewed-up belief that fruits was good for health and longevity. I hope my explanation here is clear.

On your complaint that I used technical language and biochemical equations to explain the synthesis of cholesterol in the body which you found it difficult to follow, and that you wonder if other readers understand, I am sorry about this.

 I had no choice, and here again to explain the difference between glucose and fructose (though both are simple sugars as monosaccharides that cannot be broken down further by hydrolysis or by digestion). There is no way I could explain the synthesis of cholesterol in the body or how statin drugs work without bringing in the complex pathways of biochemistry or pharmacodynamics.

Neither would I be able to explain why sucrose containing fructose in equal parts with glucose is more harmless than glucose without using the language of biochemistry again to explain. 

Sometimes it is very difficult for a scientist to explain to another scientist in another field of expertise, and I have this difficulty myself, let alone explain to lay people.

Whatever it is, scientists normally would prove their point with emperical evidence and data. Often scientists in order to carry an infornmation across to the lay public they really have to go down to their level of understanding without quoting studies published in scientific journals. 

Scientists initially search through past literature and published papers. They may then propose a new theory using previous studies as a springboard towards their new discoveries. They do this by carrying out their own studies with data to back up their hypothesis. Sometimes other scientists will try to prove the other scientists was right or wrong by carrying out their own studies. This is very daunting and challenging especially during paper presentations in scientific conferences. 

For instance,  scientists I know today have shown that both Einstein Special and General Theory of Relativity were correct by carrying out their own observations and studies such as using Michelson-Morley experiment, time dilation and length contraction for Einstein Special Relativity, or using Eddington's solar eclipse experiment, gravitational redshift and gravitational lensing effect to detect another extrasolar planet outside our own during a stellar eclipse, or they may use lunar laser ranging experiment for Einstein’s Theory on General Relativity.

More recently, scientists started using GPS satellites systems to detect very teeny tiny differences in time to prove Einstein was correct for both his Special and General Theory of Relativities

These experimental validations, along with subsequent advancements in technology and observational capabilities, have consistently supported the predictions of Einstein's theories of relativity.

Sometimes it may not be possible to get experimental data, but their methodologies must be reproducible by other scientists such as the way they are able to trace highly complex metabolic pathways.   

For instance, biochemical scientists use a variety of techniques to elucidate and understand biomolecules and to trace metabolic pathways such as by using radioactive isotope labelling to look at emitted radiation that can be detected and traced, by using mass spectrometry, nuclear magnetic resonance spectroscopy about the structure and abundance of metabolites. Alternatively, they may use enzyme assays, gene expression analysis, fluorescent probes and microscopy, metabolic flux analysis, chemical inhibitors among others. 

By combining these techniques, scientists can gain a comprehensive understanding of metabolic pathways, their regulation, and their significance in various biological processes. These are reproducibly without needing to show data 

We cannot challenge the academic and intellectual ingenuity of these scientists using their probes and their experimental studies.   

 I knew what I wrote was beyond even medical doctors who have just a basic bachelor’s degree in general medicine. 

They have just  simple broad understanding on anatomy, biochemistry (if any), physiology, pharmacology, microbiology which they do in their first two pre-clinical years, studying just a bit of each in 2 or 3 lectures before spending the remaining 3 years in various wards, each ward for only 3 or 4 months before moving on to other aspects of general medicine, mainly in appled medicine such as in  diagnosis, and treatment of diseases, all spread out over their remaining three clinical years. 

So, I don’t expect medical doctors who are basically clinicians to understand much biochemistry unless they also hold a PhD degree in biochemistry or a PhD in nutrition, in which case they would know more than my simple self.

In most of my blog articles you read here, you would notice I use very simple layman’s language to carry my message across. I hardly use any technical language with references and citations as I used to do when I was in medical research for publications of papers in scientific journals.

Since retirement I wanted to write simple articles only for lay general readers to get more readership. But if I were to use technical language then I would lose readership. I get between just 20 – 50 readers every day for my blog if I don’t write anything for days. But if I were to write a new article in simple English language, then my readership would jump to between 130 to over 800 per day.

But in certain cases, like now and in my last article on cholesterol and heart disease I can’t avoid it, else there was no way I could explain why cholesterol per sec is harmless by using simple language or explanation.

 Then they will ask me to explain in what way is it harmless when everybody including medical doctors believes it is harmful for the heart. Then how else could I explain without the language of biochemistry, pharmacology or even medicine.

I hope you understand Dr Mary Lee. Thank you for understanding why I want to avoid using scientific language except in very few cases.   

Lim jb