This article gives a great breakdown to the biggest health concerns people have about the vegan diet: protein, omega-3s, planning, and substitutes.
Her words, however, are prefaced by that of another dietitian who explains that “plants are not the best sources [of protein] because their proteins do not break down into the full range of amino acids that the human body requires for healthy functioning”.
Why is that last quote even included in the article? While it may make for a neat bit of trivia, it is irrelevant in day-to-day life, where vegans eat from more than one food group. The fact that plant-based foods lack the full range of amino acids is only problematic in extreme scenarios (i.e.: eating nothing but wheat or potatoes for months).