Mineral deficiencies help create hypoxic conditions, especially when they are needed to neutralized chemical and heavy metal toxins. Also, certain minerals are needed by the red blood cells to do their jobs efficiently. Magnesium deficient diet leads to significant decreases in the concentration of red blood cells (RBC), hemoglobin and eventually a decrease in whole blood Fe.
In fact, we find many ways in which magnesium deficiency leads to problems with oxygen transport and utilization (see below.) Iron of course is at the heart of hemoglobin so any deficiencies there are telling. And because many pharmaceutical drugs drive down magnesium levels they must be considered as major causes of lowered oxygen delivery to the cells. Said in a slightly different way, pharmaceutical drugs are a major cause of disease and death.
The mechanism whereby red cells maintain their biconcave shape has been a subject of numerous studies. One of the critical factors for the maintenance of biconcave shape is the level of red cell adenosine triphosphate (ATP) levels. The interaction of calcium, magnesium and ATP with membrane structural proteins exerts a significant role in the control of shape of human red blood cells. Magnesium enhances the binding of oxygen to haem proteins.
The concentration of Mg2+ in red cells is relatively high but free Mg2+ is much lower in oxygenated red blood cells then in deoxygenated ones. This suggests some kind of magnesium pump where oxygen climbs aboard the red cells and magnesium jumps off only to have to jump right back on the red cells again.
Magnesium is involved with the transport of ions, amino acids, nucleosides, sugars, water and gases across the red blood cell membrane. Magnesium levels drop more slowly in red blood cells than in the serum.
In healthy people, most red blood cells are smooth-surfaced and concave-shaped with a donut-like appearance. These discocytes have extra membranes in the concave area that give them the flexibility needed to move through capillary beds, delivering oxygen, nutrients, and chemical
Abnormal magnesium deprived red blood cells lack flexibility that allow them to enter tiny capillaries. These nondiscocytes are characterized by a variety of irregularities, including surface bumps or ridges, a cup or basin shape, and altered margins instead of the round shape found in discocytes. When people become ill or physically stressed (more magnesium deficient), a higher percentage of discocytes transform into the less flexible nondiscocytes.
 Influence of magnesium deficiency on the bioavailability and tissue distribution of iron in the rat. The Journal of Nutritional Biochemistry, Volume 11, Issue 2, Pages 103-108
 Terwilliger and Brown, 1993; Takenhiko and Weber; Wood and Dalgleish, 1973