Performance multivitamins are supplements that contain vitamins, minerals, and other rare nutrients that enhance athletic performance and support overall health. While they’re safe for use, it's not necessary that your body would adapt to all of them. You may occasionally face the following issues with prolonged use of a performance multivitamin:

• Upset Stomach: Digestive issues such as nausea, vomiting, diarrhea, or cramps can occur if the multivitamin is taken on an empty stomach.
• Allergic reactions: Some people may be allergic to certain vitamins or minerals, which could cause itching, hives, or difficulty breathing.
• Vitamin toxicity: Symptoms such as nausea, vomiting, headache, dizziness, and fatigue could also indicate that your body has had enough (quite literally). 
• Masking of nutrient deficiencies: Taking a multivitamin may mask nutrient deficiencies, making it difficult to identify underlying health issues. 

For a body that endures a lot of stress or athletic exertion, supplements are an essential part of the diet. But you should choose your supplement based on the results that you want to see (Too much of everything can be harmful, right?). So, refer to this checklist when you create your performance training diet chart: 

• Creatine: Most well-researched and effective supplement for boosting performance during high-intensity activities such as weightlifting or sprinting. Increases muscle mass, strength, and power output.
• Caffeine: A stimulant that can enhance endurance, focus, and mental clarity. Best known for reducing fatigue during prolonged exercise. 
• Beta-alanine: An amino acid that can increase levels of carnosine, which improves muscular endurance.
• Nitrate: Abundantly found in beetroot juice, nitrate can improve blood flow and oxygen delivery to muscles.
• Branched-chain amino acids (BCAAs): Set of essential amino acids that can reduce muscle soreness, and improve recovery after exercise.
• Rhodiola rosea: An adaptogenic herb that improves your mental ability to handle stress.
• Ashwagandha: Another adaptogenic herb that may help reduce stress, improve physical performance, and enhance core strength.
• Cordyceps: A mushroom extract that may improve oxygen uptake and utilization.
• Fish oil: A source of omega-3 fatty acids that can help reduce inflammation, and improve cardiovascular health.

As the name indicates, performance supplements are used to enhance the muscular strength of the body. They improve protein synthesis to help your muscles develop at a rapid pace, easily recover from fatigue, and handle physical stress for a longer duration. Supplements enriched with adaptogens like Ashwagandha can further contribute to your mental well-being, making your brain more receptive to its surroundings.