Sugar: Glucose, Fructose and Sucrose


Get to Know Your Sugar for Smart Longevity Diet Choices

Let’s get one thing clear. Fructose and Glucose (while both sugar) are not the same thing.

Sure, they are made of the same chains of chemicals.

The difference is in the number of molecules forming each sugar. Fructose has a ring of five and glucose has a ring of six.

This small difference translates into completely different processing pathways when you eat them. Fructose is broken down in the liver, while glucose is broken down in our cells. Insulin regulates the uptake of glucose into cells.

Here is a diagram:

Sucrose and GlucoseSucrose: That is a disaccharide, a combination of two chains – one fructose and one glucose.

Fructose: I’ll Take High Uric Acid with a Side of Fatty Liver Disease Please

Fructose has a reputation for being the ‘healthy’ sugar.

There is some merit to this. It comes from fruit, which is packed with vitamins, fibre, and minerals. It does not trigger insulin release or resistance. Instead, Fructose is broken down in the liver.

In moderation, this would not be a problem. The problem is the sheer amount of Fructose consumed. In the USA, this is the main sweetening agent in soft drinks, fruit juice and processed foods of all kinds.

The outcome is a fatty liver. Left unchecked, that can turn into fatty liver disease.

Excess fructose also causes elevated levels of Uric acid. This is associated with both heart disease and Alzheimer’s disease. If your goal is autophagy via cellular scarcity mimetics, then excess fructose will put a stop to that too.

Fructose Link to Fatty Liver Disease

Glucose: Insulin Resistance and Oxidative Stress

We need sugars. They are broken down into energy via the AMP / ATP cycle – making them vital to life. Insulin has the key role in regulating the uptake of glucose into the cells. Without it, we’d have excess sugar in our blood – causing havoc with signalling pathways, methylating cell membranes and damaging the tissues in our blood vessels.

Excess glucose triggers fat storage. That means excess adipose tissue. Inflammation follows, along with a range of unpleasant health issues. When insulin stops being effective, you’ll start on the road to Type 2 Diabetes.

Insulin resistance and type 2 diabetes

No Sugar is ‘Healthier’: They Are Bad in Different Ways

Excess sugar is a time bomb for your health.

I put it 3rd in my ‘Quick Wins’ list of longevity habits, behind quitting smoking and taking regular exercise.

My prediction for 2030 is that feeding excess sugars / simple carbs to children (and mislabelling it ‘healthy’) will be seen as bad a mistake as eating trans fats and smoking in hindsight.

Fruit juices are literally poison, add breakfast cereals, sweet soda / pop drinks, chocolate bars and cakes – and the average person is contributing to chronic conditions in mid-life and beyond every day.

Simple carbohydrates like wheat, potatoes and rice become glucose on digestion. There is no such thing as a ‘carb crash,’ it is a sugar crash. Your body is flooded with glucose, and your insulin response is triggered, resulting in a massive dip in blood sugar once all the sugar has been taken into your cells. If there is one thing that longevity science is clear on, it is that excess visceral fat caused by excess sugar consumption and a long, healthy life do not go together.

Sugar habits

It’s Not Just the Amount: How the Surface Area of Carbs Relates to a Flood of Blood Glucose

The reason that refined carbs are dangerous is the larger surface area.

When you grind flour into minute specs, our digestive juices have a larger total surface area compared to bigger pieces. Quick digestion, quick uptake into the blood and – boom – your body is flooded with glucose all at once.

That ‘healthy’ breakfast cereal is highly refined. It is a massive hit of sugar. Adding vitamins and minerals as an afterthought might be useful if you are deficient in them – though it does not alleviate the damage caused by a flood of sugar.

I’ll bang the drum on fruit juice, full-sugar soft drinks and breakfast cereals all day every day.

That insulin surge happens multiple times per day for most people. A quick sandwich, that cake in the afternoon, pasta with your dinner… all spike blood sugar.

Welcome to the aptly named ‘Glucose Rollercoaster’ of highs, lows, and constant carbohydrate / sugar cravings.

Breakfast Cereals, poison with added vitamins

But, But Mark – Fruit is Healthy!

An apple a day keeps the doctor away was not bad advice fifty years ago.

In those days, total fruit consumption was tiny. High Fructose Corn Syrup was not used to sweeten processed foods and drinks. And vitamins and mineral supplements were rare.

These days, you can get all the vitamin C you need from a simple over the counter pill (or even better, vegetables). Add fibre from healthy cruciferous greens and a balanced intake of minerals, and you don’t need that fructose-spiking apple at all.

Berries are low in sugar and high in antioxidant – and taste great.

That apple or other piece of fruit is far better than processed fruit juice.


Wrapping Up: Sugar is Poisonous – It is Also my Personal Weakness

I’ll end this page by admitting my own weakness for sugars.

When I feel down, or have not slept well, my craving skyrockets. When I see the dessert menu, a fierce internal battle begins. Chocolate, crème bule and ice cream… ahh, they are just so delicious.

While I don’t subscribe to the live like a monk to reach 120 school of thought – sugar is something to manage closely.

It is so damaging, especially with daily consumption, that the benefits of drugs, exercise, fasting and other longevity interventions will be wiped out. Getting the basics right is vital for a long, healthy life.

Fructose, glucose, sucrose (and the high-GI carbs which we break down into them) must become rare treats – and not a staple.

Longevity science can’t be any clearer, sugar is toxic and should be consumed in moderation. Sugar reduction is a major part of my health span habits guide.


More Healthy Ageing and Nutrition Guides:

Mark’s Blog





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