(Disclaimer, I’m not a doctor, and I no longer have the citations to back up a lot of this stuff. Unless otherwise mentioned, a healthy body can easily dispose of an excess of these - but whenever a random internet commenter is telling you there’s no risk of accidentally poisoning yourself, you should do your own research)
Here are some other vitamins and minerals that are worth trying, but not well known about. All of them address potential deficiencies you might realize you’re laboring under. If they work for you, you should see pretty immediate results - well before you finish the first bottle, so they’re all low investment.
Creatine. Not just for working out! It helps you store ATP, which helps with physical but also mental fatigue (i.e. brain fog). We get a small amount from meat and our body can synthesize enough to keep us operational, but the body’s standards for “operational” are pretty dismal. If you are a vegetarian or vegan, creatine is mandatory.
Tryptophan, L-Phenylalanine, Tyrosine, and GABA. Four precursor aminos to major neurotransmitter types. It costs less than a daily coffee to give your body a blank biochemical check to manufacture optimal amounts of neurotransmitters.
Methylated forms of vitamin B. Particularly methylfolate and methyl B12. Your body has to methylate most forms of most B vitamins to use them. If this methylation process is interrupted or slowed, it bottlenecks your usable B vitamin amount no matter how much regular stuff you take. But you can just take the already-methylated form instead! If you are autistic or have chronic fatigue, definitely check these out. (Autism is correlated with MTHFR gene dysfunction among other things, and MTHFR gene dysfunction makes you unable to methylate regular forms of B vitamins, in fact in some cases the regular B vitamins going un-methylated will actually jam up that process and cause lots of other problems too. At least some fraction of chronic fatigue is exactly this problem, a group of biological cycles in your body grinding to a halt because they’re jammed up. Potentially this is also part of the health benefit of cutting out bread from your diet, as most bread is fortified with folic acid for dietary purposes, and folic acid is one potential source of jams.) This one has risks, you should actively research the doses and what symptoms to be prepared for
Choline. CDP choline, or alpha-GPC specifically, as those cross the blood brain barrier. Precursor to acetylcholine, which is heavily used in the brain for many things, memory in particular seems to be highly dependent on it. (Diphenhydramine is a common OTC drug for allergies that makes you sleepy; many people use it long term as a sleeping aid, and since it is anti-cholinergic, long-term use will actually suppress your memory.) Similar principle as the group of four above, give your body all the precursors it could want.
Glycine. As we got better at farming meat animals, we stopped having to make use of the bones, skin, sinews, etc., of animals. This inadvertently cut collagen, the major source of glycine, out of our diets. Has a lot to do with muscle repair and muscle pain, as well as sleep. (The single best night of sleep I have ever had in my entire life was the first night I took a bunch of glycine, in the form of hydrolysed beef collagen.)
Zinc. A common deficiency and one that interrupts testosterone production. Apart from all the things you probably know it for, testosterone is also really important in both genders for motivation.
Potassium. Compatriot to magnesium, sodium, calcium, phosphorus. Body has excellent regulation of calcium and phosphorus and can tap into large stores of those in your bones, sodium is generally plentiful in the diet, it’s magnesium and potassium that we are likely to have mild deficiencies of. Coconut water (low sugar variety) is a convenient and safe source, but note that direct potassium supplementation carries risks.
And lastly, if you’re taking a multivitamin, pick it up and look at the RDAs on the back. RDAs are hilariously bad*, if your multivitamin manufacturer is just putting close to 100% RDA of everything in, they are just ticking boxes and don’t care about making a product that gives you the benefits you are taking it hoping to receive. Look for another multivitamin. The RDAs should be all over the place, that’s an indication they’re analyzing the research themselves. I happen to use Thorne Research.
* So, this claim is extreme enough that it does require a citation. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210929/ explains how they screwed up their statistical analysis of vitamin D. They recommended 600 IU, saying it would achieve the desired levels in 97.5% of the population. But actually that would achieve desired levels in 97.5% of the study averages in their meta-analysis pool. That is, if you took all the studies they reviewed and turned each into a human person with vit D levels equal that study’s average level, their RDA would be enough for 97.5% of those 32 synthetic people to reach the desired level. The actual RDA to achieve the result they claimed (acceptable levels in 97.5% of the population at large) is nearly 9000 IU, 15x higher.