Fructose in one form or another is grossly over consumed in the UK, but don’t get me wrong, Fructose is a legitimate carb source and if consumed in moderation, is perfectly fine for you. You see the bulk of the fructose consumed 30-50 years ago would have been via fruit, but the key here is that the fructose in fruit is also accompanied by fibre, both soluble and insoluble (pectin and the skin of the fruit), and glucose. Here’s where the balance bit comes in…
The consumption of fructose on it’s own does not stimulate insulin, which may seem like a good thing for many people, particularly Diabetics, but it’s all about how much you consume and in what form you consume it in. Diabetics are generally advised against actively adding fructose to their dietary regime because it may contribute to insulin and leptin resistance. So despite fructose’s low insulin response and potential to lower HbA1c (long term glucose control), it may actually contribute to the onset of Imparied Glucose Tolerance (IGT). Diabetics and the general public are advised to limit their fructose intake to 25-40g per day, however safe and prudent amounts would require dose response tests, but this is not practical for most, so 25-40g per day is a guide.
Link between fructose and weight gain
Fructose’s inability to stimulate insulin may be at the root of it’s potential to increase fat gain. The reason for this may be attributed to High fructose corn syrups (HFCS) and fructose sweeteners, the increased use of which has led to a 4 fold increase in worldwide fructose consumption. Incidentally the rise in fructose consumption is paralleled with a rise in obesity, diabetes, hypertension, and kidney disease. So although there are many more factors involved, fructose may be related to metabolic syndrome, a condition that includes obesity, insulin resistance, elevated triglycerides, abdominal obesity, high blood pressure and much more. Fructose can contribute to weight gain through the chain reaction resulting from a lack of insulin stimulation. Fructose’s failure to stimulate insulin means Leptin, the appetite suppressing hormone (satiating hormone) isn’t triggered, whilst Ghrelin (hunger hormone) remains upregulated. Consequently nutrient partitioning is effected and so to is appetite…in other words you feel more hungry, eat more and even run the risk of prompting insulin resistance (also a precursor to weight gain) and leptin resistance!
So what’s best?
Like with most things, keeping it simple and natural is best. Starchy carbs have been the most effective way to regulate blood sugar levels because of it’s complex chemical structure. A complex structure causes the carb source to be broken down more slowly, in turn delivering a drip feed of glucose to the body. This gradual, drip feed of glucose minimises glycaemic spikes (drastic rises in blood sugar) which in turn regulates energy levels AND minimises fat storage. Definitely consume fructose, you need to consume it if you wish to have a varied diet that is rich in vitamins and minerals. The exclusion of any food group and/or nutritional component is risky, so continue to consume intrinsically. Intrinsic sugars mean the sugar is within the cell i.e. an apple’s fructose is contained within the apples cells. Conversely apple juice, or worse still high fructose corn syrup, the likes of which you might find in a fizzy drink, is outside of the cell when consumed. Non- milk extrinsic sugars prompt a more profound hormone response because they are without fibre and glucose. This is related to glycaemic load, but is beyond the scope of this article to discuss, however it is prudent to remember that the insulin and hormonal response any sugar has on the body is lessened if it is consumed in conjunction with other foodstuffs.
There is no overall conclusion if I’m honest, but if and when you do have fructose aim to limit it to 25-40g per day, and ensure that it’s a natural form it and that it is intrinsic of the cell. Avoid HFCS’s like the plague and remember that the use of regular sucrose as a sweetener may be better for you in the long run, but not to over do it. In order to regulate blood sugar levels and minimise fat storage, you should try to consume a starchy carb source approx every 3 hours a day, this is to ensure your body receives a drip flow of energy, whilst minimising unwanted insulin spikes.
The American Journal of Clinical Nutrition, (2008). How safe is fructose for persons with or without Diabetes? Retrieved 24th June, 2014, from http://ajcn.nutrition.org/content/88/5/1189.full