Can Colas Fit into the Diet of an Endurance Athlete?

One of the hot topics on blogs and websites for ultra-endurance athletes is the use of regular cola drinks on marathon day. Athletes promote certain things on the basis of their own experience. It is important to recognize that many different combinations can work- up to a point.  Research properly done, tends to lead to conclusions that work for most people, under most circumstances, most of the time.  Are your needs the same as theirs? Can you tolerate the same foods? Are you incorporating information wisely, or combining choices appropriately? Consider these facts, and compare nutritional content, summarized at the end to help you decide whether you might try cola:

1. What is the concentration of the sugar in solution (expressed as carbohydrate  grams per 100 grams or carb %) and what  numbers of particles are in the solution (expressed as osmalality)?  The best choices are dilute, with carb % between 4-8 g/100 g and a low osmolallity – essentially sports hydration solutions.
   
   
2. What is the form of the sugar?  Not all sugars give equal benefit to the athlete, or to any normal individual.  Those most beneficial to athletes, or anyone needing a fast rise in their blood gucose are glucose, dexrtrose, and sucrose.  Fructose is considered a low Glycemic Index sugar, which is not fast enough to suit the needs of an athlete.  Fructose concentration is very high in any regular soft drinks, sweetened with high fructose corn syrup.  These have been proven to raise blood sugar too slowly, and have been associated with gut upset and with causing an increased sensation of falling blood sugar in athletes.
   
   
3. Is caffeine available? Caffeine is helpful to athletes. Cola does provide caffeine. Can it be found in other forms with or without sugar?
   
   
4. What is the acidity of the solution?  The lower the pH, the more acidic the drink, and the more likely it is to cause an upset stomach or heartburn, especially when little solid food is being taken. 
   
   
5. How fizzy is the drink?  If colas are used they must be flat to prevent reflux.
   
   
6. What is the electrolyte solution of the drink? (The table below only notes the two main ones, sodium and potassium)   We know endurance athletes need more electrolytes, but individual needs are highly variable.  There are many ways to supplement electrolytes using either tablets or more specialized sports solutions or capsules.  Note that colas are extremely low in sodium and potassium, so when using colas, more electrolyte supplementation is needed.
   
   
7. How many different fluids will be available to you on your run? Do you have a fuel belt that can hold different fluids?

What’s the bottom line?  Some cola can fit, as it is a source of caffeine and sugar, but cola should not be the principle source of carbohydrate during any endurance event. Care must be taken to take additional water and electrolytes, and to avoid taking cola close to having another beverage which has a high osmolar load. (Don’t take a cola and Red Bull liquid close together!) Cola could work in nicely as an extra beverage during a mini-meal break.

It should be noted that colas, or any sports drinks should be reserved for occasional use and should not be regular basis as part of anyone’s regular diet. Colas and sports drinks provide significant energy and very limited nutritional value.  Since humans tend to like whatever they get used to eating or drinking, there is some danger that these may be taken too often, when not required, often replacing milk in the diet. 

Being sources of phosphoric acid, colas are harmful to teeth. Colas are frequently taken in large volumes of .5 to 2 litres per day, easily contributing 25% or more of daily energy, with most coming from fructose.  The impact of this level of consumption was recently studied by researchers from the University of California, Davis, and reported last Spring in the Journal of Clinical Investigation.  The researchers randomly assigned 32 overweight individuals to drink three daily servings (the equivalent of 25% of their energy requirements of a glucose- or fructose-sweetened beverage for 10 weeks. At the end of the study period, both groups had gained similar amounts of weight, but those consuming fructose-sweetened drinks showed an increase in intra-abdominal fat, the kind that embeds itself between tissues in organs, became less sensitive to insulin (the hormone released by the pancreas that controls blood sugar), and showed signs of dyslipidemia—elevated blood levels of lipids. The fructose group also showed increased fat production in the liver, elevated LDL or bad cholesterol and larger increases in blood triglycerides. The group drinking glucose-sweetened beverages showed none of these changes.

Beverage	Main sugars	Carbohydrate g/100  g	Osmolality mmol/L	pH	Caffeine mg	Sodium mg/250 ml	Potassium mg/250 ml
Gatorade	Glucose,, fructose* sucrose	6	350	3.2	0	95-110	37
Powerade	Fructose, glucose	8.2	350-390	3.5-3.8	0	54	44
eLoad	Dextrose Sucrose	5.4		4.5	0	48	185
Coca Cola Classic- 355 ml	Fructose, sucrose	10.6	493	2.4	35	4	2
Red Bull	Not specified	10.9	601	3.3	76	200	7
Coffee –brewed	0	0	high		95	5	116
Orange Juice for comparison	Fructose, glucose	13	600	3.6-4.0	0	5	105

* in 2010 Gatorade’s formulation will change to omit fructose, and switch to dextrose

References:

SDA National Nutrient Database for Standard Reference. http://nal.usda.gov/fnic/foodcomp/search

Sílvia Helena de Carvalho Sales-Peres et al. 200.Evaluation of the erosive potential of soft drinks. Eur J Dent.;1(1): 10–13.

Stanhope, KL, et al. 2009.  Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. J Clin Invest 119(5) 322–1334