Eating well and sleeping well are not always on my agenda when traveling and not always even possible. :) So, yes I do take some vitamin supplements with me, mainly a multi-vitamin and a vitamin D capsule (both recommended by my doctor).
By the way, the whole advice from RS is: "Eat nutritiously. The longer your trip, the more you'll be affected by an inadequate diet. Budget travelers often eat more carbohydrates and less protein to stretch their travel dollars. This is the root of many health problems. Protein helps you resist infection and rebuilds muscles. Get the most nutritional mileage from your protein by eating it with the day's largest meal (in the presence of all those essential amino acids). Supplemental super-vitamins, taken regularly, help me to at least feel healthy."
Sometimes quoting things out of context distorts the advice being given.