Fructose is a common part of the Western diet. It is known for containing empty calories and having limited nutritional value and is found in a variety of sweetened foods. We all know the dangers of consuming excess sugar but fructose comes with a whole new set of health concerns. New research shows that fructose can actually damage genes. What’s the truth behind the above headline? Is there enough scientific backing to support this claim? In this article, we’ll be looking into the truth behind fructose so that you can keep yourself and your family safe.
What is fructose?
Fructose is also known as fruit sugar. It is of course, found in fruit (especially vine fruits and berries) as well as other natural sources such as honey, root vegetables and flowers. However, it is not these natural sources that are causing concern. Fruits also contain a lot of fibre which helps to slow down the digestion of fructose. They are also full of vitamins and minerals, which are an essential part of a healthy diet.
It is commercial fructose that is the worry. Derived from sugar cane, corn and sugar beet, this synthetic form of fructose is added to all sorts of food and drink products in order to improve the flavour. It is even added to certain baked goods to give them a more scrumptious brown tone.
Which foods contain fructose?
Natural fructose is found in:
- some vegetables
Synthetic fructose is used as a sweetener in soda, various soft drinks and snacks. Even some snack foods that appear to be healthy can contain large amounts of fructose. Look out for HFCS (high fructose corn syrup) on labels. Isomaltose is another culprit. It is derived from fructose and glucose and is found in beverages, cereal products, chewing gum, confectionery, preserves and diet foods. The terms levulose and invert sugar also signify fructose content in foods.
What effect does fructose have on the brain?
Changes in genes in the brain have been linked to a number of diseases including:
- cardiovascular disease
According to a new study by UCLA life scientists, it could be fructose that is responsible for damaging genes in the brain.
In the study, researchers trained a group of rats to escape from a maze. The rats were divided into three groups. Each group was given water to drink, but two of the groups had water with added fructose. The amount of fructose given to these rats was equivalent to what a human would consume if they drank a litre of soda every day. In addition to fructose water, one group of rats was also given an omega-3 fatty acid known as DHA (docosahexaenoic acid) which is believed to help reverse the effects of fructose. The study was set out to test the effects of fructose, as well as find out if DHA was as effective as it was rumoured to be.
After six weeks of consuming the special water, each group of rats was made to run through the maze once more. The rats who had been given pure water were twice as fast as those who had been given only fructose water. This proved that fructose had impaired their memory quite dramatically. However, the rats which were given a combination of fructose and DHA had similar results to those which were given just water. This implies that DHA does indeed eliminate the effects of fructose.
After putting the rats through the maze, the scientists decided to conduct other research. They discovered that the rats on the fructose-only diet had much higher levels of blood glucose, insulin levels and triglycerides than the other two groups. These results are especially worrying as they would be linked to diabetes, obesity and numerous other diseases if they occurred in humans.
The team of researchers went on to sequence over 20,000 genes in the brains of the rats. They discovered that fructose had altered over 700 genes in the hypothalamus (the metabolic centre of the brain) and over 200 genes in the hippocampus (the area where memory and learning are regulated).
Alterations to these genes can cause a number of conditions including:
- Bipolar disorder
How does this affect me?
Apart from the effects on the brain, fructose can also have an impact on other parts of your body. Fructose is metabolised by the liver, which is completely manageable if only small quantities are consumed. However, when large amounts of fructose are sent to the liver, it can damage the liver in a similar way that alcohol and other toxins do. Fructose is metabolised directly into fat, where it gets stored in your fat cells, leading to obesity, mitochondrial malfunction and obesity-related disorders.
It is really important to be aware of how much fructose you are consuming. Just one can of soda can make you exceed your daily fructose allowance. Considering that many people consume several litres of soda a day along with snacks, desserts and other sugary foods, you can see why fructose is such a problem.
As well as avoiding fructose or limiting it wherever possible, it is also worth considering your DHA intake. DHA is particularly abundant in wild salmon and is also found in other fish and their oils, flaxseeds, walnuts and certain fruits and vegetables.
RDA of fructose and DHA
Research shows that consuming 50g or more of fructose each day could have serious health implications. There are even sources that suggest a daily fructose limit of 25g. If you are concerned about your fructose intake then consider limiting the amount of fizzy drinks, sugary snacks and processed food that you consume. Fruit should form a large part of your diet and you can still happily eat 3-4 pieces of fruit each day without exceeding your fructose limit.
Fructose levels in fruit:
1 medium banana 7.1g
1 orange 6.1g
1 medium apple 9.5g
1 medium pear 11.8g
10 cherries 3.8g
1 cup of strawberries 3.8g
Â½ a grapefruit 4.3g
1/8 melon 6.7 g
1 cup of blueberries 7.4g
1 cup of dried apricots 16.4g
Fructose levels in other sources (based on a 200 calorie serving):
fruit juice 12g
baby food 21.79g
canned sweetened apple sauce 21.38g
sports drink 20.12g
raisin bran cereal 7.69g
salad dressing 7.65g
Table sugar is made up of 50% fructose.
If you are consuming high levels of fructose, then you need to reassess your diet. Although evidence supports the idea that DHA can balance out the effects of fructose, it is not advisable to use DHA to allow yourself to eat more fructose. Ideally, cut back on your fructose intake but also try to eat more foods that are rich in DHA to reap the benefits.
The top DHA-rich foods:
The RDA of DHA is 500g a week which is equivalent to two 4 oz servings of fatty fish. It is important to vary the type of fish you eat to avoid the risk of mercury poisoning. To guarantee DHA intake, you can take a fish oil supplement. When it comes to fish oils, you will also hear a lot about EHAs. These are another type of omega-3 fatty acid and are also important for our health. EHA is more linked to mood, while DHA is linked to brain development. They have both been proven to help with heart health. When taking supplements, you should aim for 500mg of DHA and EHA respectively each day.
Healthy alternatives to fructose
There are plenty of sugar alternatives out there that appear to be healthy. One example of this is agave syrup which is actually 90% fructose, making it almost as dangerous as HFCS. There are plenty of reports that state coconut palm oil is fructose-free when in reality it contains 35% fructose. This is an improvement from table sugar but is still not as healthy as many are led to believe.
Stevia is a healthy option, containing no fructose, no calories, no sugar or carbohydrates. It even has a glycemic index of 0. As it is a natural sweetener that comes from the leaves of the Stevia plant, it is a very good option for anyone looking to cut back on fructose.
The best way to limit your intake of fructose is to cut back on processed foods and to eat simple, healthy, home-cooked food whenever possible. Food labels are often complicated and with several terms being used interchangeably for one ingredient, it can be easy to overlook unhealthy ingredients. If you do buy processed food, then it is important to familiarise yourself with food labels. Taking the time to understand fructose now will help you to stay healthy in the future.