If your friend is just eating copious amounts of meat without any care for vitamin and mineral intake, then of course this leads to suboptimal nutrition. It's w

If your friend is just eating copious amounts of meat without any care for vitamin and mineral intake, then of course this leads to suboptimal nutrition. It's worth saying that recommended daily allowances are set for entire populations, and not individuals, and individuals' genes determine specific requirements. For example, people with the genetic mutation responsible for Morton's toe [1] typically absorb B6 with 65% efficiency compared to those who don't have this mutation [2]. Without adequate B6, zinc is also absorbed less. Another consequence of bad health on low-carb diets can come from high intake of linoleic acid (omega-6). This is found in "vegetable" oils such as canola, sunflower and nut (even though they are actually not vegetables) [3]. We're told to take this fatty acid for our health, but we only need trivial amounts when our diet is optimal, and too much can disrupt the way that cell mitochondria work. One fact I find absolutely amazing is that in cancer studies with rats, tumour formation is heavily influenced by levels of linoleic acid in their diet [4]. [1] https://en.wikipedia.org/wiki/Morton's_toe https://en.wikipedia.org/wiki/Morton's_toe [2] https://www.sciencedirect.com/science/article/pii/S0306987714003272 https://www.sciencedirect.com/science/article/pii/S030698771... [3] http://www.mdpi.com/2227-9032/5/2/25 http://www.mdpi.com/2227-9032/5/2/25 [4] https://www.ncbi.nlm.nih.gov/pubmed/3921234 https://www.ncbi.nlm.nih.gov/pubmed/3921234