How Exercise Increases Your Nutritional Needs — And What to Supplement

Regular exercise is one of the best things you can do for your health, but it also increases your body's demand for certain nutrients. Understanding these increased needs can help you optimise performance, recovery, and long-term health.

Magnesium: The Muscle Mineral

Exercise increases magnesium loss through sweat and urine. Magnesium is essential for muscle contraction, energy production, and electrolyte balance. Studies show that even marginal deficiency can impair exercise performance and amplify the negative consequences of strenuous exercise, including increased inflammation and oxidative stress.

B Vitamins: Energy Metabolism

B vitamins are crucial cofactors in energy metabolism. Active individuals have increased requirements for B1 (thiamine), B2 (riboflavin), and B6 (pyridoxine) due to higher metabolic rates. Research suggests that athletes with poor B vitamin status have reduced ability to perform high-intensity exercise.

Iron: Oxygen Transport

Intense exercise can deplete iron stores through several mechanisms: foot-strike haemolysis (destruction of red blood cells from impact), increased sweating, gastrointestinal bleeding during intense exercise, and reduced absorption due to the inflammatory response to training. Female athletes are particularly susceptible to exercise-induced iron depletion.

Zinc: Recovery and Immunity

Zinc is lost through sweat and is essential for tissue repair, immune function, and testosterone production. Heavy training can temporarily suppress immune function — the 'open window' theory — making adequate zinc intake particularly important for preventing illness during training blocks.

Vitamin D: Performance Factor

Vitamin D receptors are found in muscle tissue, and deficiency has been associated with impaired muscle function and increased injury risk. A study of professional athletes found that vitamin D supplementation improved sprint times, vertical jump height, and reduced injury rates.

Practical Recommendations

If you exercise regularly (3+ times per week at moderate to high intensity), consider a comprehensive supplement that covers magnesium, B vitamins, zinc, vitamin D, and iron (for menstruating women). Electrolyte replacement during and after training sessions lasting over 60 minutes is also important. Protein timing matters too — consuming 20-40 grams of protein within 2 hours of training optimises muscle repair and adaptation.

Key Supplements for Active Individuals

Here are the supplements with the strongest evidence base for supporting exercise performance and recovery:

• Magnesium: Lost through sweat and crucial for muscle function, energy production, and sleep quality. Athletes may need 400–600 mg daily. Magnesium glycinate is ideal for recovery and sleep.
• Vitamin D: Critical for bone health, muscle function, and immune resilience. Athletes training indoors or in northern latitudes are particularly at risk. Aim for 1,000–2,000 IU daily.
• Iron: Female athletes, endurance runners, and vegetarian athletes are at highest risk for sports-related iron deficiency. Test ferritin levels before supplementing.
• Omega-3: Reduces exercise-induced inflammation, supports joint health, and may improve muscle protein synthesis. Aim for 2–3 grams of EPA+DHA daily for active individuals.
• Creatine: The most studied performance supplement in history. Improves high-intensity performance, strength, and recovery. Effective for both recreational exercisers and competitive athletes.
• Protein: Active individuals need 1.4–2.0 grams per kilogram of body weight daily. Supplemental protein helps bridge the gap between food intake and requirements.

Who Needs to Supplement Based on Activity Level?

The more active you are, the greater your nutritional demands:

• Recreational exercisers (3–4 sessions/week): A quality multivitamin + omega-3 covers most additional needs
• Regular gym-goers and runners: Add protein, creatine, and magnesium
• Competitive athletes: Full testing and personalised supplementation recommended — iron, vitamin D, and electrolytes become critical
• Endurance athletes (marathon, triathlon, cycling): Electrolyte replacement during training, plus iron and B vitamin monitoring
• Strength athletes: Creatine, protein, zinc (for testosterone support), and joint supplements like collagen or MSM

Daily Tips for Exercise Nutrition

Time your supplements strategically: protein and creatine post-workout, magnesium in the evening for recovery and sleep, B vitamins in the morning for energy. Stay on top of hydration and electrolytes, especially during longer sessions or in warm conditions. Don’t train fasted regularly without supplementing — your body needs fuel and micronutrients to perform and recover. Get blood work done at least annually to catch any deficiencies early, especially iron, vitamin D, and B12. Periodise your supplementation to match your training — higher support during intense phases, maintenance during deload weeks. Listen to your body: persistent fatigue, frequent illness, slow recovery, and poor sleep are all signals that your nutritional support may be inadequate.