What supplements do we need - if any? Or is just a well balanced diet enough?
Ideally we eat home cooked food. There's variation in the ingredients. The ingredients are actual foods - ie they haven't been transformed in a factory, they've only been grown in a farm. Still. That may not be entirely enough.
Three reasons.
We may not have the variation that would be ideal. The average person's diet consist of 12 ingredients. Even as a coach who preaches variation it's super easy to eat the same things over and over.
Some foods may be harvested way before they are matured. If a banana travels from Costa Rica to Finland, it can't be yellow when it's harvested. That means it won't have all the nutrients a fresh picked banana would have. Food grown in Finland right now will not have seen sunlight in 3 months, and artificial farms may not always have a completely rich soil.
Some of the food we eat isn't going to be home grown, organic... etc. Maybe they're processed. Life is hectic at the best of times.
Vitamin D
For nordic skin some 30 minutes of sunlight is enough to get our daily need of Vitamin D. Since we don't have any sunlight over the winter months, it's necessary to supplement it.
20 ug (it's not really the u, but the greek m, but you know what I mean?) per day is the RDI, recommended daily intake. Check your packs if you get that. If you don't have any - go get it asap. Vit D is crucial.
Zink
zinc can be considered as a gatekeeper of the immune system, since the adequate function of virtually all immune cells is highly zinc-dependent.
-- Wessels, I., et al. Zinc as a Gatekeeper for Immune Function. Nutrients. 2017. 9(12), 1286.
It also boosts testosterone. Adequate testosterone levels are sinking (not zincing) and play a crucial part in performance for both men and women. Women have a lower amount of t, but still need some of it.
-- Effects of a Novel Zinc-Magnesium Formulation on Hormones and Strength L.R. BRILLA1 AND VICTOR CONTE2
OMEGA 3
Inflammation and the control thereof is in the centre of health. It plays a role in the western diet problems: diabetes, heart disease, blood pressure, overweight. Omega 3, and DHA in particular play a big part in keeping inflammation at bay. Enter the Zone by Dr Barry Sears discusses the hormonal pathways for that.
1 g of DHA per day is a good amount to aim for. Mind that 1000 m that packets usually suggest are with all Omega-3s and don't always even specify the DHA amount.
On top of that, eating fatty fish regularly (or brains, which also have high O3 content) will help. It's important enough that some evolutionary biologists have suggested that prehumans grew their brain size thanks to an increase in dietary fish (or brains, being one of the only ones on the savannah with the skills to crack open skulls).
Creatine
One of the few workout supplements that has a real documented effect on workouts. I'd go with a couple grams per day. If one wants to follow a pre bulk period one can, but it won't be strictly necessary. In a pre bulk one sort of loads up the body with the creatine. It can be considered "hifistelyä" (finnish for geeking out).
Protein Powder
1,5 - 2,2 grams of protein per kilo that you weigh. So if we're 70kg and aiming for the minimum, it'd be 105grams of protein per day. Some may easily hit that, if we eat 3 proper meals per day with good proteins in 'em. For some it's harder, especially the larger we are. For that reason a protein shake after a workout is a good idea. It increase the daily intake and makes it easier to stay consistent.
Protein intake also helps control hunger. It stimulates glucagon, which releases body fat. It builds muscle. If you can, eat real food instead of powdered.