An email exchange with William Sichel
WS: Dear Dr Stoddard.
Very much enjoyed your article "A Pain in the Gut" which I stumbled on during some research. Wish I'd found it a few years ago. A couple of queries if I may?
Do you consider fructose a GI irritant even when combined with another carbohydrate?
Me: Absolutely. Regardless of what you ingest it with, it has the potential to cause GI upset.
WS: Reference sports drink pH. Wouldn't it be better if sports drinks had a pH of 7 like water especially as we are trying to buffer excess stomach acid?
Me: A substance with a pH of 7 would not buffer anything, because it is neutral. It would have to have a pH greater than 7 to buffer acid. But, you raise a good point in that any substance with a pH of 7 if far less likely to irritate your GI tract, much like water has a very low chance of doing this. So, the goal would be to create a sports drink with a pH of 7. This is difficult to do as some ingredients in sports drinks are acidifying, such as citric acid, which does contribute substantially to enhancing the flavor of the drink. So, the goal is to get as close to 7 as possible, while of course making it taste good. Taste and acidity are competing properties that need to be balanced.
WS: With regard to pH, in my 24 and 48 hour events I am experimenting with calcium carbonate tablets (500mg per tablet), one every hour or two, to address pH issues.
Me: Sure, this is fine. But, if you choose products already formulated with pH in mind, you are less likely to need this measure.
WS: With regard to caffeine's tendency to irritate the GI system - would you recommend guarana as a better alternative.
Me: For events less than 24 hours, I don't feel you need anything else in your racing diet but carbs, water and electrolytes. For events greater than 24 hours, added protein can help stave off muscle wasting. Anything else is surplus and unnecessary, and gives your gi tract too many things to contend with during a time of compromise. Guarana does nothing for your performance, and may in fact complicate digestion due to this fact.
WS: With regard to taste/acidity, is there a role for very small quantities of sodium bicarb e.g.1.5g/L to push the pH nearer to 7 or 8?
Me: That research was done years ago, and it was found that this compound irritates the gi tract. Again, if you are choosing products formulated with pH in mind, these steps are not going to be required. Our products are always formulated with this in mind-very few, if any others, are.
WS: In events lasting longer than 24hrs, namely 48hrs and 6 day races you suggest that additional protein (presumably whey or soya) would be beneficial to stave off muscle wasting/catabolism. In these longer events at what time point would you start to introduce the protein i.e. during the first day or later?
Me: This is debatable, with no clear answer. It also varies with one important thing, and that is how successful you have been in fueling yourself with carbohydrate, as optimal carb fueling will reduce your need to catabolize protein for energy, as one of the biggest determinates of protein catabolism during exercise is carbohydrate usage. Assuming that this aspect is optimal, I would consider starting some protein intake by the end of the first 24 hours and beyond.
WS: Would liquid meal replacement products be a good idea to introduce the protein and a little fat every 4hrs or so? Or just use a good protein/carbohydrate recovery drink.
Me: I am a big believer in liquids for ultra events, as these again reduce demand on the gi tract. From an energy perspective, fat, however, is not needed at all, even for ultras, as even the leanest person has days and days worth of fat stores in their bodies for use as energy. Whether or not certain types of fat, or more specifically, fatty acids, have any 'soothing' effect on the mucosa (the lining of the gi tract), or other as of yet unknown benefits, is not yet known. Fats also may improve the palatability of what you are ingesting, which days into it can be important as you are dreaming of real food, but fat intake can just as easily be nauseating as your gut has to contend with what usually is a complicated process, that being the digestion of fat. So, based on what is known at present, a protein/carb recovery drink is fine for this purpose.