Wednesday, November 03, 2010

The Truth About Fructose Dangers

Pure crystalline fructose is an alternative natural sweetener that has long been used in the natural products industry as a common sugar substitute. Its major claim to fame is that in the short term fructose raises blood sugar far less than sucrose, the primary sugar found in white sugar that is made from sugar cane or sugar beets. Crystalline fructose should not be confused with the synthesized liquid sweetener called high fructose corn syrup (HFCS), which is made by a different process and is a mixture of roughly half fructose and half glucose (dextrose) that is widely used in the beverage and processed food industries. Unlike HFCS, fructose is a naturally occurring sugar made by plant photosynthesis that is a primary sugar in many healthy fruits. Being about 50% sweeter than sucrose, fructose can also be used more sparingly in recipes to cut their caloric intake by about 1/3.

Because of the unique challenges of formulating natural products without the use of artificial sweeteners or flavorings, sometimes a small amount of fructose is the best match for the flavorings in a product. For example, liquid vitamin B-12 has a distinct flavor profile and other sweeteners do not mask it quite as well as fructose can. Often a mixture of sweeteners may be used to create a “mouth feel” that is acceptable to consumers, who often use white sugar as their sensory standard for sweeteners. While some people may intellectually prefer other sweeteners or even white sugar, in sensory tests the fructose mixture often gets higher marks from consumers, and this leads to high compliance with recommended label uses.

I appreciate the concerns over the use of fructose. It has certainly been abused in the Western diet, especially in the form of HFCS. Americans' fructose consumption on average has tripled over the past century. But increased consumption of fruit juice and sucrose itself also are implicated in our national health decline; certainly not fructose alone, nor fructose in low doses.

According to Dr. Lustig*, an authority on fructose metabolism, human studies have not consistently shown the effect of fructose to induce insulin resistance; a negative effect reported in some animal and preliminary human studies related to altered liver metabolism. Dr. Lustig also admits that not all human studies show a negative effect of fructose on liver health or metabolic syndrome. There appear to be certain individual factors involved that make such effects somewhat idiosyncratic. Many of the studies cited are cell studies, animal studies giving high doses of fructose to mutant mice, or human studies where consumption of a lot of soft drinks were involved that provided a large number of calories comprising an unhealthy proportion (25% or more) of total daily caloric intake (about 500 calories as fructose every day). Contrast this with a healthy nutritional product that provides only a few calories, a very low percent versus those unhealthy diets!

Dr. Lustig notes that "In the hypocaloric (eg, starvation) state, fructose is as beneficial as glucose"; while also noting it has ill effects in the "hypercaloric state". He also discusses how a small amount of ethanol, a substance with similar liver effects to high fructose diets, is actually health-promoting while large amounts have the opposite effect. This reinforces that the ability of substances to elicit ill effects on the liver are typically dose dependent and require larger-than-normal amounts. In effect, 'the dose makes the poison;' as has been noted for many substances throughout history.

Dr. Lustig specifically cites three what he calls "antidotes" to the negative hepatic (liver) effects of fructose:

1. reduce the amount consumed

2. exercise

3. increase fiber intake.

So, upon reviewing these facts, the consumption of a small amount of fructose is unlikely to be harmful to the general public. Additionally, consumption of reasonable amounts may also be quite harmless if the person gets enough fiber and/or exercise. And the accepted fact that fructose does not directly raise blood glucose still gives it some short term advantages over certain other sweeteners for many people, if consumed at appropriate levels. Faster acting sugars that are higher on the Glycemic Index like glucose (which represents close to half of the sugar content of HFCS) would more immediately impact one's blood sugar, with chronic overuse eventually leading to insufficient/reduced insulin sensitivity (increased insulin resistance) that is associated with a loss of blood sugar control. Higher Glycemic sugars would affect this blood glucose control system much faster than an equivalent amount of pure fructose. And a lack of insulin sensitivity also indicates a problem in properly absorbing and recycling vitamin C in many of our body's cells; especially immune, muscle, and bone cells.

There are a variety of natural sweeteners to fit into most individuals' personalized dietary regime; but I do not promote the indiscriminate use of any sweetener, especially refined or synthetic ones. People like to have choices and will select sweeteners according to their own taste and health issues. For example, some avoid barley malt because of gluten sensitivity or certain other sweeteners because of corn allergies. People on limited diets need to scrutinize the available sweeteners and select what seems right for their own situation. But it's clear that a small amount of almost any natural sweetener, say to sweeten a cup of tea, does not seem to have any demonstrable health risk. For overly large amounts, the potential risks do increase. But a demonstrated risk level typically represents consumption of several hundred calories a day of refined sugars, including fructose, and it obviously is unwise to take in most of our daily carbohydrates in the form of refined sugars of any kind.

Consumption of small amounts of pure crystalline fructose simply doesn’t have a measureable effect on health and doesn’t need to be avoided. It’s the fructose consumed in large quantities in processed foods and beverages, where it comprises perhaps the major source of carbohydrates in the modern diet, that is the real health concern.

* Lustig RH. Fructose: metabolic, hedonic, and societal parallels with ethanol. J Am Diet Assoc. 2010 Sep;110(9):1307-21. PubMed PMID: 20800122.

1 comment:

Marco Parigi said...

Excellent article, Thank you