Table 3

Dietary supplements, sports foods and beverages that are potentially useful for footballers (adapted from Maughan et al232)

Type of supplement and examplesUseConcernsMain mechanismsProtocol
Micronutrients
Vitamin D
Iron
Calcium
Prevent or treat deficiency to help maintain health and performance.Inappropriate use or when taken with lack of monitoring or supervision can lead to health problems.See section on micronutrients.According to Doctor’s prescription.
Sports foods
Carbohydrate (CHO)-electrolyte drinks
CHO gels
Sports bars and confectionery
Recovery shakes
Protein drinks
Protein-enhanced food
Liquid meal supplements
Supply convenient macronutrients to support energy or recovery needs for training and match play.Greater cost than whole foods. Inappropriate use or amounts when taken with lack of monitoring or supervision.Macronutrient and/or fluid supply.See sections on match day (topic 1) and training (topic 2).
Performance
CaffeineReduces perception of fatigue, enhances endurance, repeated sprint performance,301 302 skill and fine motor control303 304 and improves cognitive function.304Highly individual response (both positive and negative). Side effects with high doses include anxiety, nausea, insomnia, tremors and reduced sleep quality. More serious side effects include tachycardia and arrhythmias.Central nervous stimulant.
Adenosine receptor antagonist.
3–6 mg/kg BM, in the form of anhydrous caffeine (ie, pill or powder form), consumed ~60 min prior to exercise or lower caffeine doses (<3 mg/kg BM, ~200 mg), provided both before and at half-time consumed with a CHO source.
Sports foods (or coffee) provide multiple options for delivery.
Dose of caffeine should first be evaluated using lower caffeine doses to assess response, especially if used regularly in training and match play.
Note: caffeine is currently on WADA’s monitoring programme, so the WADA list should be checked prior to use in case of a change in status.
CreatineImproves high-intensity repeated sprint performance.305 Enhances training capacity and chronic training adaptations
(muscle strength and power306 and lean BM).307 308 May also support brain function.309
Potential for 1–2 kg BM increase after creatine loading. No negative health effects following appropriate protocols.310
Falsely increased creatinine levels.
Increases muscle creatine stores, increasing the resynthesis of phosphocreatine.311Loading phase: ~20 g/day (divided into four equal daily doses), for 5–7 days.
Maintenance phase: 3–5 g/day (single dose) for the duration of the supplementation period.
Lower dose approaches (2–5 g/day) for 28 days may avoid the associated increase in BM307;
~4–6 weeks are required following chronic creatine supplementation for levels to return to baseline.
20 g of creatine (5 g dose on four occasions beginning on the same day of fatiguing exercise) may promote muscle glycogen resynthesis in the first 24 hours postexercise.312
Note: concurrent consumption with a mixed protein/CHO source (~50 g of protein and CHO) may enhance muscle creatine uptake via insulin stimulation.
β-alanineEvidence is contradictory:
may improve high-intensity exercise and repeated sprint performance.259
May enhance training capacity.305
Possible skin rashes and/or transient paraesthesia (skin tingling).
A positive correlation between the magnitude of muscle carnosine change and performance benefit remains to be established.
Sprint training may be more effective to increase the buffering capacity of the muscle.313
Increases muscle carnosine, an important intracellular buffer.314Daily consumption of ~65 mg/kg BM, ingested via a split-dose regimen (ie, 0.8–1.6 g every 3–4 hours) to give up to 6.4 g/day over an extended supplement time frame of 4–12 weeks. Protocol requires planning alongside training and match loads. Further investigation required into long-term supplementation (ie, >12 weeks).
NitrateLimited football-specific evidence. Improves economy and endurance exercise performance,305 and football-specific intermittent exercise performance in amateur players.315Individual response to supplementation.
Possibility of minor gastrointestinal upset.
Beetroot juice may discolour urine.
Performance gains harder to obtain in highly trained athletes with well-developed aerobic capacity.316
Increases tissue nitrite and nitric oxide, which reduces the oxygen cost of exercise via enhanced function of type II muscle fibres and reduces the ATP cost of force production.Protocol: acute performance benefits are most likely seen within 2–3 hours following a nitrate bolus of 5–9 mmol (310–560 mg).
Prolonged periods of nitrate intake (>3 days) may also be beneficial to performance. High nitrate-containing foods include leafy green and root vegetables, including spinach, rocket salad, celery and beetroot, which may provide a food first solution for chronic use.