With all the negative press about the dangers of eating large amounts of fructose these days, it’s not surprising people are confused as to what is good for us to eat.
Fructose is the main form of carbohydrate, and therefore the natural form of sugar, found in fruits, honey and sugar (along with a molecule glucose), some vegetables, fruit juice, flavoured mineral waters and other soft drinks.
Fructose is also found in High Fructose Corn Syrup, (HFCS), a particularly dangerous product which is made from a corn byproduct used as animal feed!
Fruit contains fibre, which can help slow down the conversion of fructose into blood sugar and some fruits contain less fructose than others, making them a healthier choice (see lists below). About 3-4 apples contains the same amount of fructose as 1 x can of soft drink, conatining HFCS!
One of the main problems of eating fructose and sugar comes from the spike in blood sugar levels. This causes the pancreas to release insulin which then converts the fructose or sugar into storable energy.
The glucose molecule (found in sugar), travels to the liver and if the liver requires fuel for energy, it will make use of the glucose. If it doesn’t need any more fuel (which is often the case in our diets today), this glucose will be stored as fat in the body.
Fructose is sent straight to the liver for converting into glycogen, which is stored in the liver, promoting fatty liver disease.
Glucose will cause more insulin to be released than fructose, but fructose will cause more triglycerides to be formed, particularly in the liver.
Fat in the liver is thought to reduce the effectiveness of insulin, which leads to insulin resistance, metabolic syndrome and diabetes. This leads to an increase in pro-inflammatory hormones being released (particularly on a cellular level), it also reduces metabolism, increases the risk of gout, may affect brain function (due to increasing uric acid levels) and joints. There is also some concern that sugar and fructose may affect the kidneys, the digestive system, eyesight (particularly cataract formation) and even a possible risk for developing certain cancers such as breast, colorectal and pancreatic cancers.
Fructose (which is also in sugar) has been scientifically proven to be a key player in obesity, not only for the abovementioned problems of fat production but because it also affects how hungry we feel. Fructose doesn’t switch off the hormone ghrelin (our hunger hormone) and therefore doesn’t allow the hormone leptin to switch on (to tell the brain we’ve had enough to eat), so this means fructose keeps telling our brains that we need to keep eating.
High fructose corn syrup and other forms of fructose, are being added to foods either in place of sugar, or as well as sugar and often other sweeteners including artificial sweeteners.
Here are some more dangers of consuming sugar and high levels of fructose:
- Feeds the non-beneficial microbiome (such as candida) in the gut, the more you feed them, the more they reproduce, and the more they demand you feed them sugar.
- Promotes ageing including wrinkling of the skin.
- Increases inflammation in the body and makes your blood more acidic.
- Can lead to osteoporosis.
- Depresses the immune system.
- Sugar mimicks anxiety, therefore if fight or flight is an issue, sugar may exacerbate this.
- May cause depression
- Rots your teeth.
- Raises your blood sugar level, which can lead to insulin sensitivity and type 2 diabetes.
- Contributes to obesity by causing you to eat more (by altering “hunger” hormones)
- Can create the urge to binge
- Is a major cause of non-alcoholic fatty liver disease
- Increases uric acid levels (think gout and inflammation)
- Is addictive (almost as much as drugs), the more you eat it, the more you want it.
- Provides ’empty calories’ with no nutritional value
- Can cause malabsorption of copper (which can affect your heart, cause anaemia and affect your thyroid)
- Robs your body of minerals.
- Robs you of energy
- Contributes to heart problems
- May increase cholesterol (particularly the bad guys LDL or VLDL)
- Can cause cancer
- Contributes to ulcers
- Can cause gallstones
- Contributes to adrenal fatigue
- Suppresses your immune syste
- Weakens eyesight
- Sugar can cause hypoglycemia (low blood sugar levels).
- May contribute to eczema
- May contribute to arthritis
Sugar or sweetening agents may appear on labels as;
- Aspartame (synthetic artificial sweetener),
- Barley malt syrup,
- Beet sugar,
- Brown sugar,
- Cane juice and cane syrup,
- Coconut palm,
- Coconut sugar,
- Corn sugar
- Date sugar,
- Fruit concentrate (which is mostly pure fructose),
- Fructose or fructose syrup,
- Glucose syrup,
- Glucose-fructose syrup,
- High Fructose Corn Syrup
- High maltose corn syrup,
- Hydrogenated starch hydrolysates
- Invert sugar,
- Maple syrup,
- Rice syrup (brown rice syrup),
- Saccharin (artificial sweetener),
- Stevia rebaudiana,
- Sugar alcohols (products using these can be called “sugar free”!),
- Turbinado sugar
FRUCTOSE CONTENT OF FOODS
Low fructose (less than 1%)
- Apricots (raw)
- Bean sprouts (such as alfalfa)
- Beetroot (fresh)
- Broad beans
- Brussel sprouts
- Chinese cabbage
- Cranberries (raw)
- Green bean
- Green capsicum
- Green chilli
- Pumpkin (butternut)
- Snow pea
Moderate fructose (1-2.5%)
- Apricots (canned)
- Banana (just ripe)
- Beetroot (canned)
- Blueberries (frozen/fresh)
- Cabbage (white/savoy)
- Guava (raw)
- Honeydew melon
- Kiwi fruit
- Peaches (fresh)
- Pear (with skin)
- Pineapple (raw)
- Pumpkin (Queensland blue & golden nugget)
- Red capsicum
- Red chilli
- Sweet potato
- Tomato (raw)
High fructose (2.5-5%)
- Banana (Very ripe)
- Blackberry (raw/frozen)
- Cherry (raw)
- Fig (raw)
- Jack fruit
- Mandarin (canned in syrup)
- Paw paw
- Pineapple (canned in natural juice)
- Star fruit
Very high fructose (greater than 5%)
- All dried fruit: figs, dates, apricots, prunes, sultanas, raisins, currants
- Apples, although the pectin slows down the conversion of fructose to blood sugar
- Berries, tinned in syrup (cherries, raspberries, strawberries, blueberries)
- Custard apple
- Dark plum in tinned syrup drained
- Nashi pear
- Pickled onion
- Tomato concentrate products (eg. Tomato paste)
My recommendation is to avoid sugar and refined fructose as much as possible, and enjoy whole pieces of fresh fruit in moderation, choosing fruits from the low fructose lists over the those from the higher fructose lists.
Eating fruits with fat and protein (such as a handful of nuts and seeds or cheese, or yoghurt), will help slow down the conversion of fructose to blood sugar. But remember, any excess fuel for energy will be stored as fat in some form or other.
Image courtesy of Tuomas_Lehtinen at FreeDigitalPhotos.net