The paper shows that it is essentially impossible for an adult male to get the recommended DI of magnesium (420 mg/day) by eating vegetables alone. As far as I can see, the paper does not resolve whether that target is too high, or whether it can be reached by eating meat or taking supplements.
The same paper also says "[...] foods containing phytates, polyphenols and oxalic acid, such as rice and nuts, all contribute to magnesium deficiency due to their ability to bind magnesium to produce insoluble precipitates, thus negatively impacting magnesium availability and absorption."
