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Dietary basics for athletes: will we ever learn?
It’s a brand new year, and a time when many athletes are thinking about how their nutrition can be optimized for the year ahead. With that in mind, SPB looks at new evidence suggesting that far too many sportsmen and women are still neglecting the dietary basics, and gives advice for those who may be confused!
Given 24/7 access to the internet and an explosion of sports nutrition knowledge – particularly relating to sport performance – this should (in theory at least) mean that most athletes have all the required tools at their fingertips for optimizing their day-to-day diet. Even when lifestyles are chaotic and planning is not a forte, the there are numerous software programmes to help design well-balanced, nutritionally complete menus, which are readily available for mere pennies or even for free. With that in mind, you might assume that in 2024, making basic mistakes with nutritional intake is a thing of the past, especially in elite/professional athletes.
But what does the recent evidence actually tell us about the nutrition habits of 21st Century athletes? Sadly, it seems that a significant number of sportsmen and women are still falling short of meeting their basic nutritional needs. As a scientific researcher and writer, I first reported on this topic for SPB back in 2010, where we demonstrated that sportsmen and women across a wide range of sports and nationalities are still vulnerable to poor nutritional habits. In particular, it seems that our growing understanding of the athlete’s nutritional needs and the easy availability of excellent online information and advice does NOT seem to have improved athletes’ levels of knowledge or diminished findings of nutritional insufficiency in the athletic community. Just a few examples of these findings include:
· Elite male swimmers – over 50% of whom were deficient in calcium and insufficient in carbohydrate intake(1).
· Female judo athletes who failed to meet their needs for iron, calcium B1 and niacin intakes(2).
· Female handball, runner, karate and basketball athletes, 100% of whom failed to meet their magnesium and copper intake requirements(3).
· Highly trained female cyclists, whose average daily intakes for folic acid, magnesium, iron, and zinc were sub optimum, while. More than one-third of the cyclists failed to consume even 60% of the recommended daily intake for vitamins B6, B12, E and the minerals magnesium, iron, and zinc(4).
· Seventy two elite female athletes where 65% failed to meet carbohydrate intake recommendations and many failed to meet their needs for for folic acid, calcium, magnesium, and iron(5).
· Over 550 Dutch elite and sub-elite athletes, the majority of whom had sub-optimum vitamin D intakes and where iron intake was sub optimum in a substantial number of the women(6).
The ‘performance in a bottle’ myth
As we shall see shortly, the frequent problem of athletes consuming poor or sup-optimum day-to-day diets has not gone away. But why is the case given there’s so much information out there? One possible explanation is that many athletes mistakenly believe that high-tech sports nutrition formulations and supplements can guarantee optimum performance, leading to a ‘performance from a bottle’ mentality. Unfortunately however, relying heavily on sports nutrition products may actually lead to a poorer basic diet quality, because many athletes simply assume that they no longer need to worry about eating high quality natural foods, thereby leading to a reduced intake of key nutrients such as fiber, antioxidants and essential fats.
A poorer-quality, low-nutrient diet is undesirable for a number of reasons – not least because such diets are associated with lowered immunity and a generally reduced resilience of the body to withstand the day in, day out rigours and cumulative stresses of training. While sports drinks and supplements have their place – especially when training volumes and intensities increase – an athlete’s day-to-day diet is actually far more important, and the true cornerstone of health, vitality and resilience to withstand the demands of training.
Female athletes and day-to-day diet
As the evidence from studies has continued to accumulate, some researchers have concluded that female athletes may be especially vulnerable when it comes to less than ideal dietary patterns and sub-optimum nutrition(7). The reasons are complex, but most likely due to the different physiology of the female body – for example monthly menses, which increases the risk of iron deficiency – along with other factors such as a desire to reduce body fat levels through increased training loads, and aesthetic reasons (particularly in sports such as gymnastics and swimming where athletes are subject to the pressure of performing in front of large crowds).
Examples of the female dimension to this problem can be seen not only in the studies listed above(2-5) but also from research suggesting that female swimmers(8) and female gymnasts(9) may be among the highest risk athletes for poor dietary practices in sport (for all the reasons cited above). In a 2021 study, which we reported in a previous SPB article, Slovenian researchers compared the risk of nutritional deficiencies in the two sports among age and performance-level matched female athletes (17 swimmers and 17 gymnasts) of the same age and all training and competing at a high level (10). As well as assessing cardiovascular health markers and body composition measures dietary intakes were analyzed using a standardized food frequency questionnaire and blood tests were carried out to determine actual nutrient levels. The key findings were (see figure 1):
· Both groups had low intake of carbohydrates, fibre, polyunsaturated fats, and high intake of free sugars and saturated fats
· The gymnasts were consuming low levels of protein
· Both groups were deemed insufficient in micronutrient (vitamin and mineral) levels but the gymnasts much more markedly so (see figure 1).
· Both groups had very significantly lower-than-recommended serum levels of vitamin D3.
Figure 1: Dietary intake of elite-level gymnasts and swimmers
Key: Black bars = swimmers; grey bars = gymnasts. SFA = saturated fatty acids; MUFA = monounsaturated fatty acids; Zn = zinc; Mg = magnesium; P = phosphorous; Na = sodium; Fe = iron; Se = selenium; Ca = calcium; K = potassium; PUFA = polyunsaturated fatty acids. The gymnasts fell significantly short of reaching the recommended intakes of most of the nutrients tested, while the swimmers fell short in many.
Males and females
Lest you assume that sub-optimal dietary patterns are mainly an issue for female athletes (therefore male readers can relax), more recent research over the past five years or so has concluded this is NOT the case. In a 2020 study on collegiate distance runners, the majority of the runners (73%) consumed less than recommended levels of carbohydrates while 50% of women and 24% of men did not meet the recommended daily allowance for calcium and 95% of the runners did not meet the RDA for vitamin D(11)!
In another 2020 study, athletes from women’s (rowing, swimming, gymnastics) and men’s (swimming, wrestling) teams at a large Midwest university underwent nutritional assessment(12). In this case, the female rowers reported the highest diet quality while the male wrestlers had the lowest (see figure 2). Regardless, the authors reported that suboptimal diet quality coupled with and increases in body fat percentage from in-season to out-of-season likely justify dietitian-led interventions year-round to improve the athletes’ dietary patterns.
Figure 2: ‘Radar plot’ of Healthy Eating Index Scores in NCAA Division I Athletes*
In a well nutritionally balanced diet, the plots would extend right out to the solid black border line. However, as can be seen, the athletes fell short on recommended dairy, whole grain, greens/beans and total vegetable intakes, with the wrestlers (small dot line) faring particularly poorly.
*Image courtesy of Taylor et al, Am J Health Behav. 2020 Jul 1;44(4):432–443
In a further (and quite damning) study published earlier this year, the dietary quality of 21 male and 73 female National Collegiate Athletic Association (NCAA) Division I athletes from 19 different varsity teams was assessed using the Healthy Eating Index (HEI - a measure of diet quality used to assess how well a set of foods aligns with key recommendations and dietary patterns published in the Dietary Guidelines for Americans) with higher scores indicating better diet quality (range 0-100)(13). It found that the average HEI score for the athletes was 59, and only nine athletes achieved an HEI score or 80 or more! There were no significant differences in HEI scores between sexes, class, majors or sport played. Most surprising of all was that whether an athlete had taken previous nutrition coursework made zero difference to how healthy their diet was. In their summing up, the authors concluded that based on US dietary guidelines for the general population, the athletes’ dietary quality was poor, which could have negative effects on their health and performance.
New research
To emphasize the fact that little has changed when it comes to athletes’ day-to-day diets, we can turn to new research by US scientists published just a few weeks ago on the dietary habits of cross-country runners(14). Published in the journal ‘Current Developments in Nutrition’, this study investigated dietary intakes during a competitive season in female and male NCAA Division I cross country student-athletes.
Twenty eight participants (fourteen men and fourteen women) were recruited from the Florida State University Men’s and Women’s Cross Country teams who competing in the 2019 cross country season. Following an initial consultation and a fitness assessment, each athlete completed five separate food records spread evenly across their competitive season. To ensure accuracy, the food-record forms were given to participants ahead of time, and the runners were asked to record the foods they had consumed for the 1–2 days preceding the day of data collection.
Instructions on accurate food record completion were provided by a registered dietician, and the runners were instructed to include details such as brand names, place of purchase, cooking method, use of cooking oils and seasonings, and time of consumption. In total, nine days of food records were analyzed for each participant: four days during the regular season and five days during the championship season. In addition, the athletes kept records of their training sessions over the season so that the researchers could assess whether their dietary intakes had impacted the way they trained. Once gathered in, all the food records were analyzed for nutritional content and then a healthy eating index score was calculated using the most up to date recommendations(15).
The findings
The key findings were as follows:
· Carbohydrate intakes were below athlete guidelines in 43% of females and 29% of males.
· None of the 28 athletes met the RDA for vitamin D.
· Only 79% of females and 36% of males met the RDA for calcium
· Most females (13) and males (11) consumed iron supplements, which took their total intake above that recommended as the upper level (averaging a whopping 110mgs per day!).
· Thirty five percent females and 50% of the males failed to meet the basic healthy eating recommendations, and nearly all failed to meet the HEI guidelines for the main food groups (except protein foods) – see figure 3.
· Rough estimates of energy intakes vs. energy expenditure indicated that approximately one-third of females and half of males were energy deficient during the regular season. With a decrease in training volume, energy deficiency prevalence decreased in the championship season to 46% of males and no females.
Figure 3: Athletes’ HEI scores for the main food groups
Outer black dotted line = ideal intake. Green dotted line = HEI scores achieved by the average US adult. Asterisks show where the shortfall is significant.
Practical implications for athletes
As more and more studies are added, the role of optimum nutrition in helping athletes to perform at their very best has never been so well understood. Moreover, strategies and detailed information on ways that nutrition can be optimized have never been so accessible. And yet with each passing year, the same findings – that the day-to-day nutrition of even elite athletes is all too often way below what it should be – continue to emerge.
Why is this the case? One possible reason is that many athletes are seduced by sports nutrition science; they assume that so long as they consume hi-tech protein and carbohydrate powders and exotic ergogenic aids, the nutritional content of their meals every day is less important. Although there’s little data on this psychological aspect of sports nutrition it is anecdotally an attitude I have personally frequently encountered while chatting to athletes at the gym.
The obvious solution remains one of educating athletes about why dietary basics are so important and how to achieve this with simple dietary changes. This can be done by either self education or by athlete coaches. For younger athletes competing at a high level, the coach is probably in the best position to help athletes understand and improve their diet. When athletes are still living at home, the role of the parents should not be neglected, and they should be involved in the education process too. As we mentioned above however, this might still not be enough as attending college courses on nutrition still made little difference to the varsity team athletes in the study mentioned above(13)!
If you are a self-coached athlete reading this who is still not sure about how to get the dietary basics right and not rely too heavily on sports nutrition products, there are a couple of excellent articles worth reading. The first is this article, which explains the common dietary mistakes athletes make, and directs athletes on how to get professional help to kick start the process. Alternatively, this article looks at nutrition hierarchy, explaining how you can ensure you’re focussing on the right elements of your diet, explaining when and how sports nutrition products may be used to complement a diet that’s intrinsically nutritious and well balanced!
References
1. Int J Sport Nutr Exerc Metab. 2004 Feb;14(1):81-94
2. Nutrition. 2002 Jan;18(1):86-90
3. Int J Sport Nutr. 1999 Sep;9(3):295-309
4. Am Diet Assoc. 1989 Nov;89(11):1620-3
5. Int J Sport Nutr Exerc Metab. 2010 Jun;20(3):245-56
6. Nutrients. 2017 Feb 15;9(2). pii: E142. doi: 10.3390/nu9020142
7. Journal of Women’s Health 2020; May 13; Vol 29, No. 5
8. Int J Sport Nutr Exerc Metab. 2014 Aug;24(4):450-9
9. Eur J Sport Sci. 2016 Sep;16(6):726-35
10. J Nutr Metab. 2021 Jan 12;2021:8810548
11. J. Am. Coll. Nutr. 2020;39(8):747–755
12. Am J Health Behav. 2020 Jul 1;44(4):432-443
13. J Am Coll Health. 2024 May-Jun;72(4):1309-1315
14. Curr Dev Nutr. 2024 Oct 15;8(11):104475. doi: 10.1016/j.cdnut.2024.104475. eCollection 2024 Nov
15. J. Acad. Nutr. Diet. 2023;123(9):1280–1288. doi: 10.1016/j.jand.2023.05.015
Andrew Hamilton
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