Jahnavi Sarma
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Written By: Jahnavi Sarma | Updated : October 4, 2019 4:31 PM IST
The liver is the only organ in the human body that is capable of metabolising fructose. ©Shutterstock
According to a new study at Joslin Diabetes Center, high levels of fructose in diet can inhibit the liver's ability to properly metabolise fat. This effect is specific to fructose. But researchers say that, contradictorily, equally high levels of glucose in your diet can actually improve the fat-burning function of the liver. According to them, this is why high dietary fructose has more negative health impacts than glucose does, even though they have the same caloric content. This study was published in Cell Metabolism.
According to researchers, fructose makes the liver accumulate fat. It acts almost like adding more fat to the diet. This contrasts the effect of adding more glucose to the diet, which promotes the liver's ability to burn fat, and therefore actually makes for a healthier metabolism.
They say that a high level of fructose is bad. It is not bad because it contains more calories. But it is bad because it affects the liver's metabolism adversely and makes it incapable of burning fat. Researchers also added that fructose makes the liver store more fat. This is not good for either the liver or for whole body metabolism. But they are quick to add that when you switch the sugar in the diet from fructose to glucose, even though they're both equally caloric, the glucose doesn't have that effect. In fact, if anything, overall metabolism is somewhat better than if they just were on plain high-fat diet.
For the purpose of the study, researchers conducted a series of studies on animals. They compared the effects 6 separate diets on metabolism. The diets were regular chow, chow with high fructose, chow with high glucose, a high-fat diet, a high-fat diet with high fructose and a high-fat diet with high glucose.
Researchers looked at various known markers of fatty liver to find out the effects of each diet. They say that they looked at levels of acylcarnitines in the liver's cells. These are produced when the liver burns fats and a high level is bad news. It indicates that the liver is burning a lot of fat. They noticed that the animals on a high fat plus fructose diet had the highest level of acylcarnitines. It was lower in animals on the high-fat plus glucose diet than in the plain high-fat diet. This showed that glucose aided fat-burning action in these animals.
Researchers also analysed the activity of a critical enzyme for fat-burning known as CPT1a. Higher levels of this enzyme is an indication that mitochondria are performing their fat-burning jobs correctly. However, in the high-fat plus fructose diet, researchers saw that levels of CPT1a are low and their activity was very low. This means that mitochondria was not function properly.
They, therefore, conclude that both high-fat and high-fat plus fructose diets damages mitochondria and makes it easier for the liver to synthesise and store fat rather than burn it. They are hopeful that a drug can be developed to block fructose metabolism. This will prevent the negative actions of fructose and help prevent fatty liver disease and its adverse metabolic consequences, including impaired glucose tolerance and type 1 diabetes, they say.
In light of this study, let us see what exactly fructose is.
There are many fruits and vegetable that are naturally sweet. This sweetness is due to the presence of fructose. The sweetness of honey is also due to fructose. Though it is a natural sweetener, it is not recommended for diabetes patients. This is because, it can spike their blood sugar levels. Sometimes, it can be sweeter than other types of sugar. The sugar you use at home is actually made up of 50 per cent fructose and the rest consists of sucrose and glucose.
Your liver has to break up fructose into glucose before your body can use it as energy. It was earlier thought to be harmless because it was a natural food source. But now, there are any studies that say that too much of this can cause health problems. But, if you have it in moderation, it is not a bad food.
Fructose is not all bad. It is lower in calories than glucose and sweeter than it too. But the only problem is that we tend to consume it in large quantities. This is when it becomes a bad food. Let us see what happens when you overdose on fructose.
You must learn to say no to this food especially if you weight more than you should. This is because, unlike glucose, fructose can convert to fat in your body. This can make you fat.
A study at Yale University says that too much of this food can affect your brain. Researchers gave 20 adults of average weight and height drinks that contained lots of either sucrose or fructose. The participants had to undergo an MRI before and after the drinks. It was seen that those who had the sucrose drinks exhibited suppressed reduced hunger signals in the brain. But this was not the case with the other group. Researchers concluded that this food can make you eat more.
The liver is the only organ in the human body that is capable of metabolising fructose. Your liver converts fructose to fat if you have it in excess. These add to your fat cells already there in the liver. It can cause liver toxicity and fatty liver disease. It can also cause metabolic disorders like type 2 diabetes and also heart diseases and even some cancers.
