A Personal Trainer’s Guide to Supplements


In the fitness industry, there are many, many supplements. With more being created and released every single year, we thought we’d break down some of the main ones, curating a comprehensive guide to those which are the most researched, science-backed and beneficial, to help you as a personal trainer understand the basics.

This article will present some of the most tried and tested supplements available, explaining what they do, what they should be used for, as well as some of their benefits. 

The Basics of Fitness Supplements

Whey Protein

Whey protein is one of the most well known supplements in the fitness industry, renowned for its rapid digestion and absorption. Sourced from milk, it is ideal for post workout recovery. Whey is rich in essential amino acids needed for muscle synthesis, making it a go to choice for many looking to improve their performance and physique.

Benefits of Whey Protein:

  • Complete Protein: Whey protein is a complete protein, containing all of the essential amino acids.
  • Satiating: Whey protein is highly satiating, meaning you get full quicker, which is beneficial for weight loss by helping control hunger.
  • Rapidly Absorbed: Whey protein is easily digestible and rapidly absorbed, making it convenient for meeting daily protein targets and supporting quick recovery post workout.

Micellar Casein

Whilst whey protein is best known for post workout recovery, micellar casein is known as the best slow releasing protein, ideal for night time consumption. Its slow absorption rate provides a steady supply of amino acids to muscles as you sleep, aiding in recovery and reducing muscle breakdown. Incorporating micellar casein into your routine can help support muscle repair and growth.

Benefits of Micellar Casein:

  • Muscle Protein Synthesis: Micellar casein supports extended muscle protein synthesis, aiding in repair and growth.
  • Satiety: Its slow digestion helps maintain fullness for longer, helping weight management and reducing the urge to snack.
  • Bedtime Use: Ideal for pre sleep consumption to help maintain positive protein balance overnight.
  • Anti Catabolic: May help prevent muscle breakdown during fasting or between meals.

Plant Protein

For those following a plant based diet, plant protein offers an excellent alternative to animal derived proteins (such as whey and casein). Derived from sources like peas, rice, and hemp, many plant proteins are not actually complete proteins by themselves, however when combined correctly, they can form a complete amino acid profile. They are not only beneficial for maintaining muscle growth and recovery, but they also offer dietary inclusivity for vegans and vegetarians.

Benefits of Plant Protein:

  • Complete Protein Options: Many plant protein sources, when combined properly (such as rice and peas), provide a complete amino acid profile, which is essential for muscle growth and repair.
  • Fibre: Many plant protein options often come with added fibre, which can aid in digestion and promote gut health.
  • Environmental and Ethical Benefits: Choosing plant proteins can have a lower environmental impact and align with ethical considerations regarding animal welfare.

Vitamin D

Vitamin D plays a key role in bone health, immune function, and overall wellbeing. Having adequate Vitamin D levels in the body is also crucial for muscle function and recovery. Vitamin D is best known for being sourced from sunlight, and also from food in limited quantities, so many people choose to supplement vitamin D, either with Vitamin D tablets or a Vitamin D spray especially in countries with limited levels of daily sunlight exposure. 

Benefits of Vitamin D:

  • Bone Health: Vitamin D plays an instrumental role in calcium absorption, supporting strong and healthy bones.
  • Immune System Support: Vitamin D supports the immune system.
  • Muscle Function: Plays a significant role in supporting muscle function, potentially maintaining strength and reducing the risk of muscle weakness.

Omega-3 Fish Oil

Omega-3 fatty acids are essential fats that may have anti-inflammatory properties, crucial for athletes and active people. Found in fish oil and plant sources like flaxseed, Omega-3s can aid in reducing post exercise soreness and help maintain heart health, as well as cognitive function. Integrating Omega-3 Fish Oil supplements or Plant Based Omega-3 supplements into your diet can support overall health and athletic performance.

Benefits of Omega-3 Fish Oil:

  • EPA & DHA: Omega-3 that is sourced from fish contains both EPA and DHA, both of which can be beneficial to the body.
  • May help maintain heart health: Omega-3 fatty acids may help maintain heart health by lowering triglyceride levels and reducing blood pressure.
  • May help reduce inflammation: Omega-3 fish oils may help reduce inflammation and exercise induced muscle soreness.

Beta Alanine

Beta alanine is best known for its role in increasing carnosine levels in muscles, which helps buffer lactic acid buildup during high intensity activities. Supplementing with beta alanine can improve endurance, delay fatigue, and improve overall performance in both strength and endurance exercise, making it a popular ingredient in many pre workout supplements. 

Benefits of Beta Alanine: 

  • Elevated Muscle Carnosine Levels: Beta alanine supplementation boosts muscle carnosine, which in turn aids pH regulation and lactic acid management during high intensity exercise.
  • Improved Endurance: Beta alanine improves overall exercise performance by managing lactic acid production, which then delays the onset of muscle fatigue and increases overall work capacity and muscular endurance.


Creatine is one of the most researched and proven supplements for increasing strength, power, and maintaining muscle mass. It works by replenishing ATP stores, the primary energy currency of the cell, helping aid performance throughout high intensity workouts.

Benefits of Creatine:

  • Increased ATP Production: Creatine aids in synthesising adenosine triphosphate (ATP), boosting energy for muscle contractions during high intensity exercises.
  • Exercise Performance: Increases ATP availability, improving strength, power, and performance in short duration, high intensity activities.
  • Promotes Muscle Growth: Leads to greater water retention in muscle cells, supporting protein synthesis and muscle hypertrophy.
  • May Improve Hydration: Creatine draws water into muscle cells which increases cell volume and may help improve hydration.


Supplementation is one of the most talked about topics in the fitness industry, and there is also a lot of misinformation about them! Whilst new supplements come out every single year, as a personal trainer, you are responsible for knowing the basics. This article has presented some of the core, top level supplements, all of which are amongst some of the most well known and highly tested/researched in the industry.

REMEMBER: as a personal trainer, it is your responsibility to provide guidance, support and advice. It is NOT your responsibility to prescribe any kind of meal plan, supplements or medication. Whilst it is not illegal for a personal trainer to suggest or even sell supplements to clients, they should be aware that should anything negative happen to clients as a result of those supplements, the personal trainer is ultimately responsible. 

This article was created to provide a basic level of awareness for personal trainers and general fitness practitioners, of some of the most well known and used supplements. 
If you’re looking for your first step to becoming a Personal Trainer, then be sure to check out our Level 3 Personal Trainer Course.