Professional athletes like football (Soccer) players are exposed to large amounts of physiological and psychological stress, which can increase infection susceptibility and threaten availability for training and competition. A new journal article investigates what effect diet and lifestyle choices have on those at increased risk.

Most professional football players take their diets seriously, however, this isn’t always the case and with up to 50 competitive, high-pressure games in a nine month period as well as training almost every day, players who do not priorities their diet put themselves at increased risk of infection.

International Journal of Sport Nutrition and Exercise Metabolism recently published a Case Study: Nutritional and Lifestyle Support to Reduce Infection Incidence in an International Standard Premier League Soccer Player. 

The case study demonstrates how a scientifically supported and practically applicable nutrition and lifestyle strategy can reduce infection incidence in an illness-prone professional footballer.

In the three months before the intervention, the player had three Upper-Respiratory Tract Infections (URTIs) and subsequently missed three competitive matches and two weeks’ training. He routinely missed breakfast and commenced morning training sessions in a fasted state resulting in a large daily energy deficit.

Throughout the 12-week intervention, his diet was altered and the player was provided with a daily sleep and hygiene protocol. There was a positive increase in serum vitamin D 25(OH) concentration from baseline to Week 12 (53 n·mol-1 to 120 n·mol-1) and salivary immunoglobulin-A (98 mg·dl-1 to 135 mg·dl-1), as well as a decline in the number of URTI symptoms (1.8 ± 2.0 vs. 0.25 ± 0.5 for Weeks 0–4 and Weeks 8–12, respectively). More importantly, he maintained availability for all training and matches over the 12-week period.

The Player

The player in this case study is an unnamed 25-year-old central defender, currently playing in the English Premier League.

Baseline anthropometric characteristics were as follows: height, 1.88 m (6ft 2); mass, 75.0 kg; body mass index, 21.2 kg/ m2; body fat, 7.8%; fat mass, 5.8 kg; and fat-free mass, 69.2 kg.

Diet and Training Assessment

Body mass and sum of skin-folds in the 12 weeks before the intervention found that the player was losing body mass and fat mass before the intervention.

Analysis revealed that the player adopted dietary habits associated with immune dysfunction. Of particular concern was that his fluid and energy intake was low, meaning he was likely to be dehydrated and in a large daily energy deficit, which has been demonstrated to suppress immune function. He also trained in the fasted state with no nutrient provision during exercise, often after only five hours sleep.

At baseline, the player was provided with a meal plan which ensured the provision of adequate energy and fluid. The diet encouraged the player to consume food and fluid before morning training and a 6 percent isotonic sports drink providing 32 g of carbohydrate and 250 mg of sodium during training. After morning training, the player consumed a drink containing 50 g of carbohydrate and 25 g of protein to promote recovery. His evening meal consisted of 175 g meat, 150 g mixed vegetables, 100 g rice or potatoes and water, he would consume this at least three hours before he went to sleep. His evening snack was 100g of Greek yogurt or cottage cheese to augment post-exercise overnight recovery, quite the change from the chocolate bar he was used to consuming after 10 pm. To help him sleep there was strictly no caffeine post 3 pm and he did not drink any alcohol.

The Centre Back was also given a vitamin D supplement as he had a borderline deficiency. He also ingested a probiotic drink containing Lactobacillus casei Shirota twice daily to reduce the incidence and severity of URTIs.

The Results

The player increased his calorie intake by 90% as well as increasing his carbs, protein and fat from baseline.

The URTI symptom score declined, demonstrating a reduction in the number of URTIs and associated symptoms over the course of study.

The player reported more stable energy levels, concentration and focus during training and matches. He slept on average for seven to eight hours per night, which he described as better quality sleep than he experienced before the intervention, he also competed in all the matches and training sessions over the 12-week period of study without any illness.

Body mass remained higher than it was at baseline over the course of the intervention. There were no appreciable changes in lean mass (Baseline, 69.2 kg; Week 4, 70.1 kg; Week 12, 69.9 kg) or fat mass (Baseline, 5.8 kg; Week 4, 6.0 kg; Week 12, 5.5 kg) over the course of the intervention.

The authors state that the large increase in daily caloric intake, as well as changes in the type and timing of macro-nutrient intake were the reasons for the positive outcomes.

This study can help footballers and practitioners seeking to deploy nutrition and lifestyle strategies, to reduce risk of illness and improve player availability for training and competition. These proven simple changes in diet and lifestyle can also help grassroots players or any athletes who feel prone to illness.