Pre supplements: Feeling lethargic and often sick, not shaking off coughs.

Our Doctor diagnosed Vitamin D deficiency.

Post supplementation (and D levels returning to normal), sick far less often with lower severity + increase in energy levels [to normal]

EDIT: Clarified energy increase is to normal.

Pretty much the same experience. Have stopped taking supplements twice. And it took me right back to 4-5 colds a winter and no energy.

I'm in Denmark. And health authorities have started recommending everyone to take supplements doing winter. And elderly all year around.

Not everyone is going to get those benefits, though.

I've been so deficient that I literally hurt. I had trouble sleeping due to the back/neck pain and had to take breaks while cooking food. Supplements took care of the pain and the extreme lack of energy, but I've never been "energetic".

The best way to describe this, really, is that if I had taken supplements before, I'd have prevented undue lethargy and tiredness. What actually made me get sick less often was not working with the public nor with children, and I never really had trouble shaking off disease when I did get sick. (I ended up deficient due to moving to a northern climate).

At best, supplements help me keep a level of normal.

Yes, I think what you're describing agrees with my family's experience.

When I said 'lethargic'->'increase in energy levels', I didn't mean increase above the baseline. I meant 'lethargic'->'normal'.

That was My experience. Was stuck in bed 22 hours a day for a year, unable to even look at phone or tv. Few months after lots of Vit D I was kayaking every weekend.