Thank you for suggesting that we reference these two papers, Darmon and Drewnoski was very insightful and most certainly useful for this article, and we now make it clearer that education is a factor of SES and a proxy for income. Lines 419-428 offer an insight into income and affluence, however we have elaborated more on income in future perspectives 533-537 and in the conclusion, lines 550-555 as it may, as you say, play a significant role in these associations.
See Murayama, N. (2015). Effects of socioeconomic status on nutrition in Asia and future nutrition policy studies. Journal of nutritional science and vitaminology, 61(Supplement), S66-S68. Darmon, N., & Drewnowski, A. (2008). Does social class predict diet quality?. The American journal of clinical nutrition, 87(5), 1107-1117. The issues raised in the well quoted Darmon and Drewnowski paper need to be considered more.