Do you want to feel the power of cell-to-cell communication? If so, according to an army of keen sellers of supplements, you need glyconutritionals, described as "a blend of specific plant saccharides that provide support for the immune system"…"and necessary for the body's creation of glycoforms, the structures on cell surfaces that 'talk' to other cells."
It's probably fair to say that when GPs hear such a spiel they try hard to remember basic biochemistry lectures. But while you dredge through your grey matter trying to recall everything you ever knew about saccharides, Krebs and other biochemical cycles, you will probably find the glyco-nutritional salesperson presenting glowing testimonials from satisfied users of their products.
However, your foray into biochemistry will at least enable you to argue ration-ally when presented with claims that our food contains "only two or three of the eight essential monosaccharides we need". You should by then have recalled that our bodies can make many essential compounds from basic building blocks — in this case, various mono- and disaccharides.
In my experience, the multi-level marketing company representative will usually mention the poor quality of the typical diet, quote textbook references on glycolipids and glycoproteins, mention various research scientists and may even throw in a Nobel prize winner to support the products on offer.
So what should we make of all this? Well, there's no doubting the validity of glycobiology. Glycoproteins and glycolipids, which combine sugar-based molecules with either proteins or lipids, do play essential roles in many biochemical cycles.
Glycolipids are found in the brain and in the myelin sheath around nerve fibres while glycoproteins are found in cell walls, collagen and the bone matrix. They're also involved in hormones and enzymes and are needed for transporting nutrients. Claims that glycoproteins have a role in the immune response are correct because they are sites for attachment or recognition for viruses and bacteria.
Such facts are available in any biochemistry textbook. But these facts do not mean that we need to take supplements of these substances.
Glycolipids and glycoproteins are intermediary substances made in the body, just as our bodies make the enzymes and many other biochemical intermediaries we need. We don't experience a glyconutrient deficiency that can be remedied with a pill.
After years of searching, I am still unable to locate a single clinical trial published in a recognised scientific journal that has studied people given glyconutrient supplements. I continue to ask representatives selling these products (made by a multi-level marketing company called Mannatech) for such studies, but instead I get photocopies of biochemistry textbooks and testimonials from satisfied customers who claim the products have cured them of various health problems.
Often I have been told that a Nobel prize was awarded for work on glyconutrients. Like others, I have looked into these claims and found Dr Gunter Blobel, from Rockefeller University in New York, was awarded a Nobel Prize in Medicine in 1999 for his research on identifying signals that direct proteins to specific parts of a cell.
Dr Blobel's work is universally acknowledged for its usefulness in understanding hereditary diseases such as cystic fibrosis, familial hypercholesterolemia and hyperoxaluria. But the implication that Dr Blobel's work gives validity to some requirement for glycoprotein supplements is at best far-fetched.
This world-renowned cellular and molecular biologist is not connected with Mannatech and has not published research on their supplements or any need for such supplements. A PubMed search for Dr Blobel and glyconutrients yields nothing.
There is no evidence that we are unable to make our own glycolipids or glycoproteins. Nor is there any evidence that some people are deficient in these compounds and have a greater incidence of various diseases. And without a single trial in support of Mannatech supplements, and taking into account their high price, I do not think they deserve support from those who believe in evidence-based medicine.
Any GPs who are tempted to promote Mannatech products would do well to look up the files on a Queensland GP whose registration was cancelled for two years after making unsubstantiated claims that Mannatech products were effective against several serious diseases.
Sales of creatine supplements are booming in the US and are especially popular among male athletes, who use it to increase muscle size and strength. Studies of college students in the US show that creatine is used by many boys, but only a few girls.
Creatine is an amino acid derivative that comes from protein in the diet and is also made in muscle from amino acids. Within skeletal muscle, creatine forms creatine phosphate and acts as a direct source of energy for the muscle cells.
There are many exaggerated claims made about creatine, but the use of creatine (usually as creatine monohydrate) certainly has more credence than glyconutrients. However, it's not suitable for everyone and supplementation needs supervision.
Creatine monohydrate has been studied in athletes and supplements can increase muscle levels of creatine phosphate by about 20%. However, some people - usually those whose base levels of creatine phosphate are already high - have no response to extra creatine. Once levels have increased, taking higher doses does not produce a measurable improvement in performance.
The Australian Institute of Sport (AIS) classifies creatine under its A supplements, which means it is supported for use by AIS athletes with supervision. The AIS web site ( www.ais.org.au) is a good reference site, and lists safe supplements as well as those for which there is no proof of benefit for athletes and a group of compounds that they recommend should not be used.
The AIS recommends creatine only for certain athletes and only under careful supervision since the benefits and risks are not entirely understood. It should be taken with carbohydrate and the athlete should expect a weight gain of about 1kg due to fluid retention. Correct dosing protocol is important and can be checked on www.ais.org.au/nutrition/documents/SupCreatine.pdf
There are suggestions that creatine is unsuitable for those with type 1 or type 2 diabetes. Studies in rats have shown increases in fasting insulin levels and increasing insulin resistance. In type 1 diabetes, creatine could increase sensitivity to insulin, so risks may outweigh any potential benefits. Those with a history of renal disease may also be at increased risk of renal problems, especially if they exceed the recommended dose of creatine. Some people taking creatine also report muscle cramps and diarrhoea.
In general, creatine should be used only by specific athletes and requires supervision to check dose and potential side effects. It's not suitable for teenagers and the AIS does not use it for those who are still growing.