• Protein Bread.
• Protein Milk.
• Protein Crisps.
• Protein Cereal.
• Protein Ice-Cream.

You can walk into almost any supermarket today and it won’t take you long to find something with the word protein printed across the packaging. There is an abundance of products that traditionally you wouldn’t pick up for their protein benefits that are now sold and smartly marketed as “high protein”. Protein has arguably never been more prominent in mainstream nutrition. 

However, this isn’t necessarily a bad thing for athletes, and for the general population, as protein plays a fundamental role in tissue growth, repair, and maintenance. Most athletes are now aware that consuming enough protein matters.

The Others

But when one nutrient takes the spotlight, what happens to all the others? 

Iron, potassium, calcium, vitamin D, omega-3, carbohydrates, and even adequate overall energy intake just to name a handful, don’t receive quite the same coverage. They aren’t usually marketed in supermarkets with the same passion or covered through media with the same depth. Nevertheless, they each play a justified and significant role in an athletes training, recovery, and of course performance. 

Iron

This isn’t an argument for reduced protein consumption, it’s instead to encourage looking beyond protein. Iron is viewed as an essential mineral for performance as it plays a vital role in supporting oxygen transport and cellular energy production (Badenhorst et al., 2021). In other words, iron assists in oxygen transportation around the body both in the red blood cells (haemoglobin) and in the muscle cells (myoglobin). This is critical during sport performance as muscles need sufficient oxygen to produce energy efficiently, maintain contractions, and even post exercise to support the body’s increased oxygen demands during recovery. Efficient oxygen delivery and transport during and after exercise, enhances recovery, reduces fatigue, and improves overall performance. 

Inadequate iron intake can affect endurance athletes, such as long-distance runners, cyclists and swimmers, as well as team-based athletes, such as footballers and netball players, whose high intermittent and physical demands can increase fatigue sensitivity (Solberg and Reikvam, 2023; Brassington et al., 2026). The need for sufficient iron consumption is even more crucial for female athletes when compared to their male counterparts. This is due to increased blood loss through menstruation and the potential for inadequate dietary intake caused by restrictive dietary practices or attempts to reduce body weight (Muñoz, Villar and García-Erce, 2009; Harrabi et al., 2025). Hence, it is imperative that athletes, especially female athletes, are including enough iron in their weekly diet. 

Food sources that are high in iron include meats and fish like beef, lamb, turkey, tuna, and sardines. For athletes on a vegetarian or plant-based diet good sources of dietary iron include; lentils, kidney beans, spinach, cabbage, pumpkin seeds and dates, however research suggests that to increase the absorption of iron from plant-based sources (non-heme) they should be consumed in conjunction with sources of vitamin C from something as simple as a glass of orange juice (Skolmowska and Głąbska, 2022).

Vitamin D & Calcium

Vitamin D & calcium are nutrition’s Bonnie and Clyde; it’s criminal how effective they are when they pair up. Between calcium and bone health lies a direct link as calcium plays an essential role in bone mineralisation, along with phosphorus, which provides the bone with strength and rigidity. The British Dietetic Association (BDA) also affirms that calcium plays a role in muscle contraction and nerve function. Vitamin D is then essential as it helps the body absorb the calcium and phosphorus as well as regulating calcium/phosphate homeostasis. This contributes to and supports overall bone health. Additionally, vitamin D also has a role in muscle function (Sale and Elliott-Sale, 2019). While calcium provides a fundamental building block for bones and teeth, Vitamin D helps regulate the processes that allow calcium to be absorbed and utilised effectively. 

Athletes, especially those in contact sports, place high levels of mechanical stress on their skeleton whether it be from running, jumping, changing direction, lifting and/or collisions. This causes a bone response to exercise that is influenced by many factors, one of which being an athlete’s nutrition (Dolan et al., 2020). Therefore, athletes must take seriously the importance of maintaining bone health to enable them to comfortably commit to their potentially busy training and performance schedule. Inadequate calcium and vitamin D status can increasingly compromise bone health and in turn foster concerns around bone weakness and potential injury. An injured athlete is one that must take a step away from what they love to focus on recovery, a scenario best avoided. 

Certain athletes are more susceptible to inadequate calcium and vitamin D levels. The latter is more likely to occur amongst athletes who train predominantly indoors, those who lack exposure to sunlight, and athletes with darker skin, as higher levels of melanin can reduce vitamin D production from sunlight. Low calcium status is more likely to be found amongst plant-based athletes due to them not consuming dairy products. Vitamin D levels can be increased through sunlight exposure where possible, oily fish, eggs, and supplementation where appropriate. Whereas calcium levels can be increased by milk and dairy, or for plant-based athletes through calcium fortified tofu and plant-milks.

Potassium

Potassium is a nutrient essential to human function, playing a vital role in maintaining fluid balance, osmolality of cells, blood pressure regulation, muscle function, and more (McLean and Wang, 2021). Potassium becomes increasingly relevant to athletes for the role it plays in muscle contractions (supporting repolarisation after each contraction) and blood pressure regulation (counteracting sodium and promoting vasodilation). Sufficient potassium intake helps to support muscle and cardiovascular function (Senay, 2023). Moreover, sufficient potassium consumption may help negate some of the physiological consequences linked to hypohydration, prevalent in combat sports especially during aggressive cuts that some athletes undergo for fight preparation (Pallarns et al., 2016). Potassium therefore plays an important supporting role in athletic performance across most, if not all, athletic populations due to its role supporting fundamental physiological processes.

Potassium is one of the body’s key electrolytes and so is often supplied to athletes through electrolyte drinks and powders. However, potassium can also be found abundantly in different fruits and vegetables such as bananas, watermelon, avocados, potatoes, sweet potatoes, squash, and tomatoes. Another pretty good reason to get your 5-a-day in!

Food for Thought

Protein has earned its place in sports nutrition, but I don’t think it should dominate the conversation!

Iron, vitamin D, calcium, and potassium are only a few nutrients that could have been explored throughout this article. Each plays a fundamental role in providing an athlete with a complete nutritional profile, and their importance should not be overlooked just because protein has the spotlight. The next time you see “High Protein” plastered across a food package, there’s nothing wrong with reaching for it, just remember to look beyond the words on the front.

References

Badenhorst, C. E., Goto, K., O’Brien, W. J. and Sims, S. (2021) ‘Iron status in athletic females, a shift in perspective on an old paradigm’, Journal of Sports Sciences, 39(14), pp. 1565-1575.

Brassington, R. J., Mara, J. K., Ball, N., Waddington, G., Paul, K. and Cooke, J. (2026) ‘Match demands and physical qualities of female athletes in Australian football, rugby union, rugby sevens, and rugby league: a scoping review’, Biology of sport, 43(1), pp. 405-428.

Dolan, E., Varley, I., Ackerman, K. E., Pereira, R. M. R., Elliott-Sale, K. J. and Sale, C. (2020) ‘The Bone Metabolic Response to Exercise and Nutrition’, Exercise and sport sciences reviews, 48(2), pp. 49-58.

Harrabi, M. A., Fendri, T., Chaari, F., Ayed, R., Hadadi, A., Boughattas, W., Mezghani, I., Kallel, C., Rebai, H., Turki, M., Ayadi, F. and Sahli, S. (2025) ‘Efficacy of 8-week oral iron supplementation on fatigue and physical capacity in young women with iron deficiency anemia: An uncontrolled pilot clinical trial’, PloS one, 20(10), pp. e0334499.

McLean, R. M. and Wang, N. X. (2021) ‘Potassium’,  Advances in Food and Nutrition Research, pp. 89-121.

Muñoz, M., Villar, I. and García-Erce, J. A. (2009) ‘An update on iron physiology’, World journal of gastroenterology : WJG, 15(37), pp. 4617-4626.

Pallarns, J. G., Martinez-Abellan, A., Lopez-Gullon, J. M., Moran-Navarro, R., De la Cruz-Sanchez, E. and Mora-Rodriguez, R. (2016) ‘Muscle contraction velocity, strength and power output changes following different degrees of hypohydration in competitive olympic combat sports’, Journal of the International Society of Sports Nutrition, 13(1), pp. 10-10.

Sale, C. and Elliott-Sale, K. J. (2019) ‘Nutrition and Athlete Bone Health’, Sports medicine (Auckland), 49(Suppl 2), pp. 139-151.

Senay, L. C. (2023) ‘Potassium in Exercise and Sport’,  Macroelements, Water, and Electrolytes in Sports Nutrition: CRC Press, pp. 151-165.

Skolmowska, D. and Głąbska, D. (2022) ‘Effectiveness of Dietary Intervention with Iron and Vitamin C Administered Separately in Improving Iron Status in Young Women’, International journal of environmental research and public health,19(19), pp. 11877.

Solberg, A. and Reikvam, H. (2023) ‘Iron Status and Physical Performance in Athletes’, Life (Basel, Switzerland), 13(10), pp. 2007.

About the Author

Jamal is a final-year BSc Sport and Exercise Science student planning on pursuing an MSc in Sport Nutrition. He has a particular interest in nutrition and its role in performance, recovery, and health. He takes a hybrid approach to his training pushing his physical limits through strength training, boxing, and swimming with the aim of becoming a well-rounded athlete. This personal interest in performance coincides with his passion for taking a similarly comprehensive approach to nutrition. He hopes to make evidence-based sports nutrition more accessible and to explore the often-overlooked nutritional factors that can influence performance across different sporting disciplines.