Vitamin A is pretty scarce in many diets, yet a 2010 paper shows that sufficient vitamin A produces 30% increase in ATP production. [0] ATP facilitates energy transfer between cells [5]

Lots of sources including wikipedia vitamin A page [6] don't seem to recognize the role of Vitamin A in energy transfer between cells. [2] [4] Wikipedia page for ATP does not mention the link with Vitamin A either. [7]

There are reports of Vitamin A supplements producing psychological productivity energy boost akin to caffeine. [1]

One cup of boiled carrots is sufficient daily intake of vitamin A. [2] Boiling the carrots increases vitamin A absorption due to breaking down the cellulose in carrots. [2]

Other sources include cooked tuna, cooked squash or pumpkin, cooked sweet potato, cooked spinach/kale/collard/chard/bok choy, or beef/fish liver. [3] If you aren't eating a good amount of these foods every day you are likely deficient.

VitaminA Vitamin-A (algolia has trouble with "Vitamin A" searches)

[0]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812036/

[1]: https://www.reddit.com/r/Supplements/comments/cxm1pg/vitamin_a_increase_in_energy/

[2]: https://www.livestrong.com/article/542992-does-boiling-carrots-destroy-the-nutrients/

[3]: https://www.myfooddata.com/articles/food-sources-of-vitamin-A.php

[4]: https://www.mayoclinic.org/drugs-supplements-vitamin-a/art-20365945

[5]: https://en.wikipedia.org/wiki/Adenosine_triphosphate

[6]: https://en.wikipedia.org/wiki/Vitamin_A

[7]: https://en.wikipedia.org/wiki/Adenosine_triphosphate