‘An apple a day keeps the doctor away’, may have been true once upon a time when we were all slim and car-less. All fruit is rich in fructose and at one time fructose was hailed as a natural sweetener with a lower Glycemic Index than sucrose, so didn’t raise insulin as much. Fructose is 1.73 times sweeter than sucrose, so we need less, and was touted as an all round good apple, recommended to diabetics to control blood sugar whilst satisfying their sweet cravings. The food industry loves fructose because it is highly soluble in water, retains moisture well and so improves the quality, texture and shelf life of their food products. Added to this we are encouraged to eat our 5 a day of fruit and vegetables – and who wants to eat 5 sprouts and a stick of celery when we can eat a banana, orange and some super sweet strawberries?
Sadly fructose has had its day in the sun and is now associated with developing diabetes, metabolic syndrome, increasing cholesterol, developing non-alchoholic fatty liver disease , increased inflammation and is even being linked to gout and wrinkly skin. How can something that starts out so well end so badly? Well, part of the answer lies in how fructose is metabolised by the body. Unlike glucose, which can be metabolised and used every cell in the body, fructose is mainly metabolised in the liver. In that conversion it uses ATP – ATP is often likened to a rechargeable battery to produce energy – and a by-product of this is uric acid. And this is why a high fructose diet is linked to increased Gout. So if prone to gout, it would be wise to restrict fructose in the diet which means avoiding fruit juices altogether and eating minimal fruit. Processed foods and drinks should be examined for how much fructose they contain.
In the liver fructose not used by the liver for energy is converted to triglycerides, and so raises cholesterol levels. Due to its nature, fructose, having been converted to free fatty acids (what triglycerides are made out of), builds up in the liver and so causes the non-alchoholic fatty liver disease or hepatic steatosis. It also messes with the genes responsible for burning up body fat in the mitochondria1 as the footnoted review goes into. However, I recommend an ice-pack on the head to fully understand why.
The review also went into how fructose fed rats and hamsters showed the typical insulin resistant impaired memory and a lack of brain adaptability. Both of these matter – loss of memory is obvious; however, decreased adaptability – or plasticity – in the brain is equally dreadful. Contrary to what we used to believe, we now know that the brain adapts and changes to stimulation until we die, so it is important to keep the brain active and healthy and not mess it up with excessive amounts of fructose from the diet. Herbal tea is sounding more and more attractive.
When I used to eat fruit, I always found eating an apple for a snack made me feel hungrier. It wasn’t so bad with berries, but this was because I used to eat a lot of them and then went on to eat some nuts or ham or whatever else I could lay my hands on. Research now shows why regular apple eating can make us hungry – taking in fructose does not stimulate insulin, but it also does not raise leptin, which is the hormone that tells us we have eaten enough. On top of this, it does not lower ghrelin, the hormone that tells us we are hungry. So a glass of freshly squeezed orange juice or a coke with lunch will soon have us wandering off to the tea trolley in search of a spare biscuit or two.
Needless to say, it gets worse. As the footnoted review states
Leptin resistance may be an early hallmark of fructose and feeding-induced metabolic dysfunction.
Added to this is
fructose induced inflammation which is now recognized as a common feature of the metabolic abnormalities observed in obesity.
It has been found that taking in fructose activates various inflammatory pathways, which further increases cholesterol, as it happens. Metabolic abnormalities are principally diabetes and metabolic syndrome, which is insulin resistance along with high cholesterol levels and high blood pressure, characterised by an apple shaped fat body. Body fat stored from fructose goes around the organs as opposed to under the skin, leading to the apple shape – or the potato shape: big belly, skinny arms and legs.
Within this inflammatory pathway, the gut wall is damaged and bad bacteria in the gut proliferate. There is some slight good news here, and that is that taking oligofructose, a way of feeding the good gut bacteria, blunted the fatty liver disease and circulating cholesterol in rats. So if a high fructose diet has been eaten, then taking a course of high quality probiotics will help reverse some of the damage, and the same will go for sugar mad children.
In all of this, the American Heart Association recommends limiting sugar intake to to no more than 100 calories a day for women and 150 calories a day for men. Children should have less. Fructose is particularly bad for children as the linked article, Fructose – how worried should we be? by George A Bray goes into. This is mainly because there is no nutrition in fizzy drinks but also because of the conversion of fructose to uric acid, as mentioned above. High levels of uric acid, apart from causing gout, also lower levels of nitric oxide, essential for controlling blood pressure and protecting the walls of the blood vessels (arteries and veins). So children drinking a lot of fizzy pop or fruit juice are predisposing themselves to obesity, heart disease, diabetes and gout as they grow up.
Finally fructose is terribly aging. The blog on AGEs went into this – and fructose sprinkled on food for its browning properties is even worse than sugar for aging us inside and out. Rats fed fructose had “significantly more aging markers such as cross-linking in the collagen of their skin.”2 So if fear of getting fat and forgetful is not enough, getting wrinkly might be reason to cut out the fruit juice in favour of the Earl Grey Tea.
The above video is 8 min 21 secs long and is an interview with Robert Lustig, a paediatric endocrinologist who treats obese children. He does talk about high-fructose corn syrup, used in America in virtually everything, it seems, and which makes simple fructose seem almost friendly it is so bad. However, Mr Lustig also blasts away at sugar and fructose. The interview is interspersed with a couple of researchers for the sugar cane companies, so the sugar addicts amongst us can hang onto those parts. If we want to know more, here is a youtube video with Robert Lustig that is about 1 hour 30 mins long.
To live a lean, healthy life with minimal need for botox then restoring sugar in any form to a rare and splendid treat to be enjoyed once or twice a year is a must. After all, caveman couldn’t scurry off to the local Mars Bar bush for a sugar fix.
- Dekker MJ SuQ. Fructose: a highly lipogenic nutrient implicated in insulin resistance, hepatic steatosis and the metabolic syndrome. AJP-Endo Nov 2010 vol.299 no 5 E685-E695 [↩]
- Louisa L Williams. Radical Medicine. Cutting edge natural therapies that treat the root causes of disease. Healing Arts Press. [↩]