What about pregnant people who are too nauseous to eat? or the elderly?
This advice is for the general population. Under Certain circumstances such as pregnancy or in elderly, or in those who have a vitamin deficiency vitamins are definitely crucial. So always check with your physician to make sure that you don’t have a deficiency, and if you are pregnant, or have been placed on certain medications that may block absorption then vitamins can be of benefit. In those circumstances, specific guidelines exist to help with replacement.
What about vitamin B12? Vitamin D for those of us living above/below a certain latitude? Algae-based long-chain omega-3 fatty acids?
Yes, algae is in our top 20 foods: http://teamsherzai.com/brain-health-foods/