Pure Gym Limited

A beginner's guide to supplements

Written by Lewis Gaffney | Personal trainer at Birmingham City Centre

For as long as I can remember, supplementation has been a hot topic within gyms so let me start by clearing up a common misconception: supplements aren't bad for you but neither are they necessary.

So if they're neither of these things, should you take them? 

To help you decide whether you want to include any supplements your diet, here's a breakdown of pros and cons of consuming the most common fitness supplements in the market.

What are supplements?

Supplements are products intended to provide nutritional value to the body but not used to substitute for food. They can be split into two categories: food and non-food.

Food supplements provide the nutrients you'd get from a well-balanced diet. The most common food supplements are protein powders and fish oils (Omega-3).   

Non-food supplements provide the nutrients found in ineffective doses in our diets and are usually used to improve a specific area of our health, recovery or performance. Two common examples that can't be provided in effective doses by our diets but improve athletic performance are caffeine and creatine.

Let's look at some of the most common food and non-food supplements in the market.

Pros and Cons of Top Supplements

Protein Powders

Pros: Protein powders are a convenient way of adding more protein to your diet particularly if you're struggling to meet your protein targets, or if you're on the go, as they can be a easy source to pack and consume.

Cons: On the flip side, they aren't a great source of other vitamins and minerals, so I would suggest that you'd be better off getting your protein from a natural food source like chicken, fish or beans, in each of your meals, which provide added nutritional benefits too. 

If I were to pick a protein powder, which one would I pick?

If you're looking for a protein powder, I recommend checking out the biological value (BV) as they're not all the same. The biological value indicates how much of the protein and amino acids can be absorbed by the body. The higher the number, the more your body will be able to absorb it.

To give you an idea of how this biological value can differ, here's how some protein sources compared.

  • Whey protein isolate: 159
  • Whey protein concentrate: 104
  • Egg protein:
  • Pea protein: 65
  • Casein: 77

Looking at these examples, whey protein isolate seems the best option but with so many brands out there it can be hard to know which brand is best. I usually go to https://labdoor.com/ to check which brands have the highest ratings.

Carbohydrate Powders

Pros: Carbohydrate powders are great for delaying fatigue which can help boost performance over time. Doses should be capped at 30-60g of carbohydrate powder per hour of exercise due to how fast we can digest and use it.

Carbohydrate sources such as dextrose and multi dextrose are more likely to have the edge over food sources for sporting performance as they're quicker to digest. 

Cons: However, they won't provide fibre and won't fill you up as much as food. These powders are popular with lean bodybuilders and long duration athletes as they help you stay hydrated, replenish carbs after exercise and increase overall calorie intake.

Carbohydrate Drinks

Popular with people exercising for long periods of time, carbohydrate drinks are consumed to help replenish our glycogen stores to help with recovery and performance. The isotonic variety is often best as they also help reduce dehydration.

Pros:  These drinks differ from powders as they are readily made and easily accessible and often contain small amounts of electrolytes too. Hypertonic drinks are the most effective as they often contain around 10g of carbs which helps replenish glycogen during bouts of intensive exercise.

Cons: However, most people don't exert themselves enough to really need hypertonic drinks, so it can be a waste of your money.


Pros: Dissolved in water, these powders help create fluid balance during and after exercise, and prevent dehydration and muscle cramps. That's why they're popular with people undertaking lengthy or high intensity exercise. To get the maximum benefits make sure the powder includes potassium, calcium, sodium and magnesium.

Cons: Due to their main use being for long duration or high intensity exercise, the sugar content in these drinks is nothing to worry about however overuse of these drinks can cause weakness and nausea due to the high levels of magnesium so it's important to consume plenty of plain water along side them.

Fatty Acids (Omegas)

Pros: Research shows that these supplements can help reduce inflammation, reduce cholesterol and improve brain health. Most effective in doses of 2-4g a day, they are beneficial to everyone but particularly when recovering from surgery or if overweight.

Cons: High doses may interact negatively with some other medications for diabetics or anyone using blood thinning drugs so if these apply to you, please consult your medical professional prior to use. Not all brands contain equal amounts of compounds within the supplement, speak to your medical professional to see which blend will work best for you.

Vitamin D

Pros: The benefits of this supplement include increased bone health and reduced symptoms associated with colds, Crohn's disease, diabetes, pain and depression. Being deficient in vitamin D can also cause rickets or cardio disease, which is why the government recommends using a Vitamin D supplement during the winter months.

Cons: Most supplements only contain doses of 400 IU (International units) per tablet and although this is within the NHS guidelines some research has shown that we need up to 1000 IU's per day to see results. Supplementing only seems to be dangerous when taking around 4000 IU's or higher per day as this can cause higher levels of calcium in the blood which can lead to kidney disease.


Pros: While not often thought of as a supplement, caffeine can provide effective results such as increased mental and performance and fat loss. As a stimulant, caffeine works to keep us alert by blocking certain receptors in the brain. Just 3-6mg per kilogram of body weight can improve physical performance for up to two hours. You'll find caffeine in sports drinks, coffee and caffeine supplements.

Cons: Drawbacks to using caffeine are that it may disrupt sleep if drank later in the day. If an excess of 400mg is consumed on a regular basis, then our bodies can become immune to its effects so it's not as effective.


Pros: This supplement has been shown to contribute towards increased maximal strength, improved sprint performance and increased ability to repeatedly perform at maximum effort. Suitable for men and women, recommended doses are 3-6g per day around the workout period.

Cons: It's not unusual to experience weight gain of 1-2kg in the first few weeks of use, but the majority of this will be water.


Pros: Magnesium deficiency has been associated with muscle weakness, nausea, unwanted weight loss, sleep deficiency and muscle cramps. The US Department of Health recommends supplementing anywhere between 350-420mg a day for adults, however, it's recommended increasing that dosage for those undergoing heavy exercise to combat these symptoms.

Cons: Supplementation above and beyond the recommended daily amounts can cause side effects such as: irregular heartbeats, low blood pressure, diarrhea, muscle weakness and nausea.

Beta Alanine

Pros: Taken prior to exercise in dosages of 80mg per kilogram of body weight (with no side effects shown), beta alanine supplement allows you to perform harder for longer when exercising in short, intense bursts of between 60 and 240 seconds. 

Cons: The only known side effect of this supplement is called acute paresthesia which is an uncomfortable but harmless tingling of the skin. Many people find this uncomfortable however these effects do not last long.

To Supplement or not to Supplement?

I hope this information can help you to decide whether you need or want to include any supplements into your diet. There are plenty more supplements not mentioned here so be sure to do your own research before using them. If you do decide you want to add any supplement to your diet, I recommend adding them one at a time so you can monitor the effect they have more clearly and assess whether it's worth including them.

About the author: Lewis Gaffney is a Personal Trainer at PureGym Birmingham City Centre. His mission is to provide people with the best training methods possible for their goal and teach methods for long-term health and fitness. His background in sport and injury rehabilitation has given him a brilliant understanding of how the body moves, and how it reacts to different stresses. Follow Lewis on Instagram for more free training and nutrition tips: @lewisgaffneyfitness


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