Updated: Oct 3, 2019
The short answer to this is you don't have to take any supplements. They are called supplements for a reason, they are there to add to your diet should you need them. I would always recommend trying to get all your macronutrients and micronutrients from food first before relying on newest superfood tablet or shake. But supplementation does have it's place and I too use some alongside my diet, so we'll go through the ones I take and why.
Whey protein has been proven to help with fat loss and muscle building, and are various sources such as casein and whey. They contain BCAAs which are branched chain amino acids, the important one being leucine that's helps with protein synthesis (muscle growth).
Again you don't have to take this, I have a protein shake maybe every other day to help get my overall protein intake in if I find that I'm struggling to get it in with my food. I personally opt for a whey isolate as it's slightly purer that concentrate of hydrolysed.
So this is one of the most studied supplements out there and has been proven to work. creatine monohydrate is beneficial for building strength and can give you the capacity to get through a few more reps in a workout.
I take this first thing in a morning every day. There is a lot of information as to when to take, how much to take and whether or not you should load it up when you first start taking it. Me personally just started taking the recommended daily dose of 3-5g every morning and didn't bother loading it on the first week like some people would advise. It can be taken over long periods and has no side effects as it does naturally occur in the body anyway, supplementing with creatine just adds to the muscles natural stores.
You don't need to take this if your getting enough from your diet or you get a good exposure to sunlight, but as we live in the UK let's face it glorious sunshine isn't what we are known for. So vitamin D is important for healthy bones, teeth and muscles. Having a lack of or a deficiency in vit D can lead to weak bones.
If you have oily fish, red meat and eggs as part of your diet chances are you won't need to supplement with vitamin D. I tend to supplement with this during the winter months when we don't get a lot sun.
Again this is a supplement and not necessary.
So this is very popular supplement and is the most widely used stimulant in the world. That been said there is no conclusive evidence that states that caffeine helps with any strength gains in the gym. But it has been shown to decrease levels of fatigue which may benefit you during high intensity/volume workouts.
Yes I have some form of caffeine before I train to give me that pick me up to put the extra effort in to my session. It can have a lesser affect the more you take it so I try to have a few days of no caffeine what so ever every 3 weeks or so. It does raise your heart rate so be carful in what amounts you take it in as some pre-workout drinks have up to 300mg in which personally gives me heart palpitations. I tend to go for a drink that has no more than 180-200mg of caffeine in at a time. And be aware that the daily recommended allowance is 400mg for a healthy adult.
So I also take a multivitamin in a morning to just to make sure I'm not missing anything from food and I take turmeric as it's a natural anti inflammatory and I have a few joint aches and pains that I find are improved by taking this.
None of these supplements are necessary like I said at the start they are there to supplement a healthy diet and lifestyle they are not magic pills.