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Nutrition and Physical Activity
Athletes (and Coaches) Say the
Darndest Things
Christine Rosenbloom, PhD, RD, CSSD
From 1952 to 1969, the television show ‘‘House Party,’’ hosted Sports Drinks and High-Fructose
by Art Linkletter, featured a segment of interviews with
Corn Syrup
school children, aged 5 to 10 years old. The segment entitled I quit drinking sports drinks because they contain the
‘‘Kids Say the Darndest Things’’ became a hit, spawning ‘‘crack’’ of sweetenersVhigh-fructose corn syrup. (20-
year-old male cross-country athlete)
several books and a revival series hosted by Bill Cosby from
1998 to 2000. This article revisits the premise by reviewing High-fructose corn syrup (HFCS) has become a
some of the ‘‘darndest’’ things that athletes and coaches say 4-letter word with many consumers, including athletes.
about nutrition and sports performance. This review will High-fructose corn syrup is an ingredient in the most
popular sports drinks, and because sports drinks are
cover topics on caffeine and hydration, sports drinks and formulated to provide fluid, simple carbohydrates, and
high-fructose corn syrup and dental erosion, and fasting for electrolytes lost in sweat, they are often recommended to
competition. Nutr Today. 2009;44(2):77–80 endurance athletes. Containing 55% fructose and 45%
sucrose, HFCS is used in sports drinks to replace some of
the sucrose. High-fructose corn syrup is used for 2 main
P roviding nutrition counseling to athletes and
coaches is a rewarding experience, but every once
in a while, an athlete or a coach will say something
that makes even the most seasoned nutrition professional
say ‘‘huh?’’ Like the time an exhausted distance runner
reasons. The first is costVsugar prices rise and fall with
climate change or political upheaval in sugar-growing
countries.1 High-fructose corn syrup is derived from
corn, an abundant crop in the United States; therefore, a
ready and steady source of this sweetener is a bonus for
swore she had iron deficiency anemia when the problem the food industry. The second reason is the stability that
turned out to be the low-carbohydrate diet she was liquid HFCS has over crystalline sugar especially in acid
consuming because her mom insisted that she follow the beverages such as soft drinks and sports drinks.
meal plan outlined in the Dr Atkin’s weight loss program. High-fructose corn syrup got its bad reputation in 2004
The distance runner’s hematological profile was normal, when Bray et al2 published a paper in the American
but she was consuming only 50 g of carbohydrate per day Journal of Clinical Nutrition speculating that the increase
or 1 g of carbohydrate per kilogram of body weight, in HFCS in the US food supply paralleled the increase in
compared with 7 to 8 g of carbohydrate per kilogram that obesity in children and adults. That set off a fire storm of
is recommended for an endurance athlete. Then there blame, and the idea that HFCS was ‘‘sweeter’’ than
was the baseball coach who watched a late night sucrose and was metabolized differently from sucrose,
television infomercial and ordered a case of a supplement setting the stage for increased consumption and
that purported to ‘‘tan and trim’’ his athletes. He increased obesity, was firmly set in the minds of many
subsequently found out that the supplement contained consumers. (For an excellent review of the chemistry and
synephrineVa substance banned by the National metabolism of HFCS, see Schorin M. Nutr Today.
Collegiate Athletic Association. The ‘‘tanning’’ ingredient 2005;40:248-252.) The belief that HFCS is sweeter than
gave him an odd orange tint; the ‘‘money back’’ guarantee sucrose and causes sugar craving, thereby encouraging
never materialized. In this article, we examine some of people to overconsume HFCS-sweetened beverages, is
the ‘‘darndest’’ things said by athletes and coaches. not true.3 High-fructose corn syrup is not
Nutrition Today, Volume 44 Number 2 March/April, 2009 77
Nutrition and Physical Activity Athletes (and Coaches) Say the Darndest Things
fructoseVfructose is sweeter than sucrose, but HFCS is micronutrients that are needed in energy metabolism.
closer in chemical composition to sucrose (sucrose is However, athletes, especially endurance athletes; those
50% glucose and 50% fructose). If sucrose is given a participating in intermittent high-intensity sports such as
reference sweetener value of 100, crystalline fructose soccer, football, and basketball; and those who exercise
is assigned a value of 173, indicating that fructose is in hot, humid environments can benefit from consuming
sweeter than sucrose. However, in sensory tests, HFCS is sports drinks.
rated equivalent to sucrose in sweetness and retains that
sweetness at varying temperatures3; therefore, HFCS is
not sweeter than ordinary table sugar. Caffeine and Hydration
Some athletes judge a food by its glycemic index (GI), I don’t drink any beverages with caffeine because they
and athletes may choose low-GI foods before exercise to cause dehydration. (32-year-old professional athlete)
help moderate blood glucose response during the
exercise, while choosing high-GI foods and fluids after For decades, the conventional wisdom has been that
a hard workout to rapidly replace muscle glycogen. The because caffeine has diuretic properties, athletes who are
GI of HFCS has not been established, but the GI of soft trying to hydrate before exercise or rehydrate after
drinks sweetened with HFCS is 63Vvery close to the activity should avoid caffeine. When you add that advice
GI of sucrose4 at 68. If using GI as a determinant to select to the abundance of caffeine found in today’s food and
a beverage, then it would be good choice for a beverages, everything from energy drinks to gum,7 it is
post-workout fluid to help restore muscle glycogen to hard for an athlete to avoid caffeinated products. In a
prepare the athlete for the next day’s workout or review on caffeine, water balance, and exercise
competition. performance, Armstrong8 questioned the long-held
Another idea that Bray and colleagues put forth was advice given to athletes to avoid caffeine. Armstrong
that HFCS changes the body’s signals for satiety, causing reviewed 30 years’ worth of research on caffeine,
an overconsumption of beverages and foods sweetened hydration, electrolyte losses, and heat illness in active
with HFCS. Melanson et al studied the short-term effects people. Methylxanthines, the stimulants in coffee, tea,
of HFCS versus sucrose consumption on appetite, and cocoa, stimulate the central nervous system and the
circulating glucose, insulin, leptin, and ghrelin in lean cardiac muscle. Caffeine is the primary stimulant in
women. The researchers gave the women isocaloric diets coffee, theophylline is the stimulant in tea, and
with either sucrose- or HFCS-sweetened beverages taken theobromine, also found in tea, is the stimulant in
as 30% of energy. On the day after the beverage chocolate and cocoa.8 Of the 3 methylxanthines,
consumption, the women could eat ad libitum. Blood theophylline is the most potent diuretic, with a weaker
chemistries revealed no significant differences in fasting effect found for caffeine and theobromine. After
blood sugar, insulin, leptin, and ghrelin levels, and there scrutinizing all of the evidence on caffeine and water
was no difference in calorie or macronutrient intakes on balance, Armstrong8,9 came to the following conclusions:
the day after the trial with sucrose or HFCS.5 In a review
& Consuming caffeine at 300 to 400 mg or less per day
of HFCS, energy intake, and appetite regulation,
has a similar diuretic effect as water does but does not
Melanson and colleagues agree that there is insufficient
impair exercise performance or health.
evidence to suggest that HFCS is metabolized differently
& Both water and caffeinated beverages can result in
than sucrose or causes alterations in appetite compared
retained bodily fluidVwhen dehydration is present,
with other sweeteners. However, most of the research
more fluid is retained, whether the fluid comes from
has been conducted on lean men and women, and few
water or caffeinated beverages.
data on the effect of HFCS on obese people have been
& Caffeine-containing beverages do not cause greater
presented.
increases in core body temperature, sweat rates, or
The American Medical Association issued a statement
performance times, even under hot environmental
about HFCS at its 2007 annual policy-making meeting,
conditions.
saying, ‘‘At this time there is insufficient evidence to
& The effect of larger doses of caffeine (99 mg caffeine per
restrict the use of high fructose syrup or label products
kilogram of body weight) on fluid and electrolyte
that contain it with a warning.’’6
balance is not well studied, so it wise for athletes to
Although current short-term studies on lean adults do
avoid excessive caffeine, but there is no need to entirely
not show any detrimental effects of HFCS, it is wise for
avoid caffeine.
all athletes to moderate sugar intake and obtain needed
carbohydrates from whole grains, fruits, and vegetables. Field studies of caffeine intake have supported
These carbohydrate-containing foods not only provide Armstrong’s review. In a crossover design, participants
the energy needed by active people but also deliver exercised twice a day for 2 hours at each exercise bout
78 Nutrition Today, Volume 44 Number 2 March/April, 2009
Athletes (and Coaches) Say the Darndest Things Nutrition and Physical Activity
for 3 consecutive days. Study participants could drink ad Two independent dental examiners evaluated dental
libitum and drank the equivalent of 84 oz (7 cans) of erosion using a standardized index. Clinical examiners
either caffeine-free soft drink or caffeinated soft drink. In did not know the results from the questionnaires. The
the 3 days of the study, there was no difference in results showed that athletes with high sports drink
hydration measuresVurine-specific gravity, urine ingestion did not have any significant dental erosion.13
volume, or body weight.10 The limitation of this study is recall bias and a
Therefore, it seems that the advice that caffeine is convenience sample, but it was the first study of dental
dehydrating and should be avoided by athletes is not an erosion in ‘‘real’’ athletes.
evidence-based recommendation.9 Coombs12 reviewed the literature on sports drinks and
dental erosion and concluded that isolating one dietary
Sports Drinks and Dental Erosion component, in this case sports drinks, as the sole cause of
dental erosion in young, healthy athletes is simplistic.
I quit giving the kids sports drinks because they are the
Dehydration, a condition that is not uncommon in very
leading cause of cavities; I let them have juice or fruit
active individuals, may play more of a role in promoting
drinks instead of sports drinks. (High school soccer coach)
tooth wear than the choice of beverages does. Saliva
The idea that sports drinks cause dental erosion and an helps to buffer acids in the mouth, and saliva flow is
increase in dental caries was postulated when in vitro decreased with dehydration.12,14 Young14 advises athletes
studies showed that the acid pH of sports drinks (as well to think about drinking adequate water to avoid
as carbonated soft drinks, energy drinks, fruit juice, and dehydration; limit the time that acid drinks stay in the
fruit drinks) contributes to the dissolution of tooth mouth, especially when dehydrated; eat more fresh fruit
enamel. Dental erosion is an irreversible loss of the hard to stimulate saliva production; get adequate dietary
surface of the tooth and not related to decay caused by calcium; and avoid excess alcohol, which can exacerbate
microorganisms.11 Consumption of sports drinks has dehydration.
been on the rise in groups of people other than athletes
because of marketing efforts of the major sports drinks Fasting for Competition
companies.12 Active children and adolescents have been
I want to ‘‘pre-fast’’ my athlete before Ramadan begins so
consuming more soft drinks, sports drinks, and energy
he will get used to fasting. (cross-country coach referring
drinks than previous generations of children have, so to an athlete who fasts during the month of Ramadan)
dentists wanted to know if these acid beverages are
harming the dental health of this population. Kitchens Athletes who are practicing Muslims fast during the holy
and Owens11 tested the effect of 7 beverages (Coca Cola month of Ramadan. The fast lasts from sunrise to sunset
Classic, Diet Coke, Gatorade, Red Bull, Starbucks and includes total abstinence from food and water.
Frappuccino coffee drink, Dasani bottled water, and tap Ramadan occurs during the ninth month of the Islamic
water) on surface roughness (the precursor to dental calendar and often coincides with preseason training and
erosion) by immersing previously extracted teeth in each competition in fall sports such as cross-country, soccer,
of the beverages. The results of this in vitro study showed and basketball.15 Anecdotally, athletes report that the
that the cola drinks (both regular and diet), sports first week of fasting is the most difficult, but as the month
drinks, and energy drinks caused significant roughness to progresses, they adjust to the daytime fasting. Having
the tooth surface but the coffee drink and waters did not. worked with professional basketball players and
The critics of in vitro studies suggest that immersion collegiate soccer, basketball, and cross-country athletes
of extracted teeth in acidic beverages is not how athletes who fasted for Ramadan, our strategy has been to
use sports drinks in the ‘‘real’’ world. Although the maximize food and fluid intake in the predawn meal and
authors of this study said their protocol simulated how post-sundown meal. For collegiate athletes, the biggest
children and adolescents use these beverages, they admitted challenge is the morning mealValthough they rise for
that their clinical model was a ‘‘worst case scenario.’’11 morning prayers, many prefer to crawl back into bed
In response to the in vitro studies, Mathew et al13 instead of eating before sunrise.
studied in vivo sports drink consumption in collegiate Carbohydrate stores in the body are limited. Skeletal
athletes. Researchers recruited a convenience sample of muscle stores about 300 to 500 g of glycogen
304 athletes in a variety of sports at The Ohio State (1,200-2,000 calories), and the liver holds 60 to 100 g
University (wrestlers were excluded because of their (240-400 calories), with a scant 15 to 20 g
weight control practices and swimmers were excluded (60-80 calories) in the blood.16 Maximizing the body’s
because of their exposure to chlorinated pool water). carbohydrate stores is one of the best ways to provide
Athletes completed a detailed questionnaire and were fuel to working muscles during an activity of long
interviewed about foods, beverages, and dental hygiene. duration, such as distance running. As exercise intensity
Nutrition Today, Volume 44 Number 2 March/April, 2009 79
Nutrition and Physical Activity Athletes (and Coaches) Say the Darndest Things
increases, carbohydrate oxidation provides about 70% of 2. Bray GA, Nielson SJ, Popkin BS. Consumption of
energy needs at the beginning of exercise, with more than high-fructose corn syrup in beverages may play a role in the
three-quarters of the carbohydrate coming from the epidemic of obesity. Am J Clin Nutr. 2004;79:537Y543.
muscle stores of glycogen.16 When carbohydrate stores in 3. Forshee RA, Storey ML, Allison DB, et al. A critical
examination of the evidence relating high fructose corn
muscle and liver are exhausted, the athlete becomes syrup and weight gain. Crit Rev Food Sci Nutr.
exhausted too. Fasting a cross-country athlete before 2007;47:561Y582.
Ramadan would put the athlete at risk for earlier fatigue 4. Melanson KJ, Angelopoulos TJ, Nguyen V, Zukley L,
than if he/she started the fast with full glycogen stores. By Lowndes J, Rippe JM. High-fructose corn syrup, energy
maximizing glycogen stores in the days leading up to intake, and appetite regulation. Am J Clin Nutr.
Ramadan and by providing adequate carbohydrate in the 2008;88(suppl):1738SY1744S.
morning and evening meals, athletes can participate in 5. Melanson KJ, Zukley L, Lowndes J, Nguyen V,
high levels of training even during the religious fast. Angelopoulos TJ, Rippe JM. Effects of high-fructose corn
Ideally, athletes in heavy training would be ingesting syrup and sucrose consumption on circulating glucose,
carbohydrate during exercise as well as pre-exercise and insulin, leptin, and ghrelin and on appetite in
normal-weight women. Nutrition. 2007;23:103Y112.
for recovery. Jeukendrup17 suggests that by ingesting 6. AMA finds high fructose corn syrup unlikely to be more
different simple carbohydrates that have different gut harmful to health than other caloric sweeteners. http://
transporter systems (glucose and fructose), the oxidation www.ama-assn.org/ama/pub/category/18691.html.
of carbohydrate can be increased 20% to 50%. However, Accessed July 29, 2008.
during Ramadan, athletes do not eat during the day, so 7. Schardt D. Caffeine: the good, the bad, and the maybe.
the best dietary strategy is to provide sufficient Nutrition Action Health Letter. March 2008.
carbohydrate before the fast to fill muscle and liver 8. Armstrong LE. Caffeine, body fluid-electrolyte balance, and
glycogen stores. Sports dietitians will have the exercise performance. Int J Sport Nutr Exerc Metab.
opportunity to have a living laboratory in 2012 when the 2002;12:189Y206.
London Olympic Games (held July 27 through August 9. Ganio MS, Casa DJ, Armstrong LE, Maresh CM.
Evidence-based approach to lingering hydration questions.
12, 2010) coincides with Ramadan (July 20 through Clin Sports Med. 2007;26:1Y16.
August 19, 2012).15,18 It is estimated that one-third of 10. Fiala KA, Casa DJ, Roti MW. Rehydration with a
athletes participating in the Olympic Games will be caffeinated beverage during the nonexercise periods of
Muslims (R. Maughan, written communication, 3 consecutive days of 2-a-day practices. Int J Sport Nutr
January 7, 2009). Exerc Metab. 2004;14:419Y429.
Sports dietitians have the opportunity to dispel 11. Kitchens M, Owens BM. Effect of carbonated beverages,
common nutrition and sports performance myths by coffee, sports and high energy drinks, and bottle water on
staying abreast of current research and providing the in vitro erosion characteristics of dental enamel. J Clin
evidence-based recommendations to athletes and coaches. Pediatr Dent. 2007;31:153Y159.
Athletes and coaches will still say the ‘‘darndest’’ things, 12. Coombs JS. Sports drinks and dental. Am J Dent.
2005;18:101Y104.
but we can help guide them to sound nutritional practices. 13. Mathew T, Casamassmo PS, Hayes JR. Relationship
between sports drinks and dental erosion in 304 university
Christine Rosenbloom, PhD, RD, CSSD, is a professor of nutrition at athletes in Columbus, Ohio, USA. Caries Res.
Georgia State University. She provides nutrition counseling to the athletes at 2002;36:281Y287.
Georgia State and conducts research in sports nutrition. 14. Young GW. Tooth wear: diet analysis and advice. Int Dental
Correspondence: Christine Rosenbloom, PhD, RD, CSSD, Division of J. 2005;55:68Y72.
Nutrition, Georgia State University, Atlanta, GA 30303 15. Ramadan on the net. http://www.holidays.net/ramadan/.
(crosenbloom@gsu.edu). Accessed November 8, 2008.
16. Ivy JL. Role of carbohydrate in physical activity. Clin Sports
Med. 1999;18:469Y484.
REFERENCES 17. Jeukendrup AE. Carbohydrate intake during exercise and
1. White JS. Straight talk about high-fructose corn syrup: what performance. Nutrition. 2004;20:669Y677.
it is and what it ain’t. Am J Clin Nutr. 2008;88 18. London 2012. http://www.london2012.com. Accessed
(suppl):1716SY1721S. December 15, 2008.
80 Nutrition Today, Volume 44 Number 2 March/April, 2009
