Focus on a healthy, balanced diet and make sure you include enough variety focusing on plenty of colorful vegetables, fruits and nuts. Exercise regularly and take good care of your body getting enough sleep and enough sunshine.
Farming nowadays produce crops with 2/3 of the vitamins you used to get, due to exhausted soil [1]. Wild salmon has 33% more Omega-3 than the ones grown in tanks [2].
Even if you manage a 100% fresh/unprocessed food (unlikely nowadays), you still ingest less vitamins than your parents did.
The farming techniques used today are different than the ones used in the 1800s and before. So the vegetables/fruits today are not as healthy as they were. Especially when you consider consumers use visual guidelines for health (ie are the fruits plump, juicy, and colorful) instead of nutritional content.
The demand for "good looking" food is higher than the demand for healthy food. The food grown in Cuba is probably healthier since the farmers can't afford the more expensive, modern farming techniques.
Diet and exercise/lifestyle go a long way, but individual variation is still large -- perfect example: my wife and i have identical diets and eating habits, and my vitals are all "normal" -- yet she is b12 and vitamin D deficient, because her lower intestine doesn't absorb those into her body as effectively as mine does.
I have this unsubstantiated belief that most people taking supplements live an unhealthy life otherwise. Many people want a magic solution to things, and taking lots of pills seems to be cure du jour.
This is made worse by the fact that there do exist people for whom supplements are required. Without justification, everyone thinks they fall in that group.
It's certainly "enough". Anyone who takes supplements beyond that is no longer "satisficing" they are "maximizing".
I'm mostly vegan, and I tend to just try to focus on eating a good diet, but I do also try to supplement with things that are harder to find in my diet naturally: some kelp for iodine, B-12 since I don't eat much eggs (or meat for that matter).
I recently ordered some D3 spray, for reasons I can't really remember. Every now and then I go online and try to learn as much as I can about the research and make a judgement call.
A balanced diet is enough, but it's hard to know what "balanced" really means in this world where our food system has been so skewed towards processed foods and meat.
Nope, because even if you do all those things, at some point your body will start to slow down, you'll get aches and pains you didn't used to have, and some time you will suffer illness.
At that point many people are keen to see great benefits from placebos, and the door to quack medicine is open.
Maybe not entirely. By overdosing on artificial "vitamins", you drain your body out of the elements needed to process these. The rabbit hole goes a few miles deep. http://www.whale.to/a/shea1.html
Nothing is ever enough these days. People that exercise 5 to 7 times a week used to be considered healthy by all: now they are called "active couch potatoes" or something like that by some people if they also happen to have some sedentary hobbies when they are not working out. Recent studies have shown sitting a lot to be unhealthy in the long run: just sitting! Regardless of whether the person is active or not.
It feels like there is almost nothing that you're doing right, if you're living in the modern world. It's like we benefit from the actual services of a modern civilization greatly, but also suffer greatly from working and supporting that very same civilization (as opposed to a primitive one). I guess we ideally should all be working at standing workstations, rotated with a treadmill workstation because evidently standing too much also hurts you, and then in our leisure time we should spend it on some games/activities that boils down to jumping through the hoops that our ill-fitted-for-modern-civilization bodies and minds need to live a healthy life in a modern context.
Focus on a healthy, balanced diet and make sure you include enough variety focusing on plenty of colorful vegetables, fruits and nuts. Exercise regularly and take good care of your body getting enough sleep and enough sunshine.
Is that not enough?