Intravenous administration of nutrients can achieve serum concentrations not obtainable with oral, or even intramuscular (IM), administration. For example, as the oral dose of vitamin C is increased progressively, the serum concentration of ascorbate tends to approach an upper limit, as a result of both saturation of gastrointestinal absorption and a sharp increase in renal clearance of the vitamin.3 When the daily intake of vitamin C is increased 12-fold, from 200 mg/day to 2,500 mg/day, the plasma concentration increases by only 25 percent, from 1.2 to 1.5 mg/dL. The highest serum vitamin C level reported after oral administration of pharmacological doses of the vitamin is 9.3 mg/dL. In contrast, IV administration of 50 g/day of vitamin C resulted in a mean peak plasma level of 80 mg/dL.4 Similarly, oral supplementation with magnesium results in little or no change in serum magnesium concentrations, whereas IV administration can double or triple the serum levels,5,6 at least for a short period of time.Various nutrients have been shown to exert pharmacological effects, which are in many cases dependent on the concentration of the nutrient. For example, an antiviral effect of vitamin C has been demonstrated at a concentration of 10-15 mg/dL,4 a level achievable with IV but not oral therapy. At a concentration of 88 mg/dL in vitro, vitamin C destroyed 72 percent of the histamine present in the medium.7 Lower concentrations were not tested, but it is possible the serum levels of vitamin C attainable by giving several grams in an IV push would produce an antihistamine effect in vivo. Such an effect would have implications for the treatment of various allergic conditions.Magnesium ions promote relaxation of both vascular8 and bronchial9 smooth muscle – effects that might be useful in the acute treatment of vasospastic angina and bronchial asthma, respectively. It is likely these and other nutrients exert additional, as yet unidentified, pharmacological effects when present in high concentrations.In addition to having direct pharmacological effects, IV nutrient therapy may be more effective than oral or IM treatment for correcting intracellular nutrient deficits. Some nutrients are present at much higher concentrations in the cells than in the serum. For example, the average magnesium concentration in myocardial cells is 10 times higher than the extracellular concentration. This ratio is maintained in healthy cells by an active-transport system that continually pumps magnesium ions into cells against the concentration gradient. In certain disease states, the capacity of membrane pumps to maintain normal concentration gradients may be compromised. In one study, the mean myocardial magnesium concentration was 65-percent lower in patients with cardiomyopathy than in healthy controls 10 implying a reduction in the intracellular-to-extracellular ratio to less than 4-to-1. As magnesium plays a key role in mitochondrial energy production, intracellular magnesium deficiency may exacerbate heart failure and lead to a vicious cycle of further intracellular magnesium loss and more severe heart failure.Intravenous administration of magnesium, by producing a marked, though transient, increase in the serum concentration, provides a window of opportunity for ailing cells to take up magnesium against a smaller concentration gradient. Nutrients taken up by cells after an IV infusion may eventually leak out again, but perhaps some healing takes place before they do. If cells are repeatedly “flooded” with nutrients, the improvement may be cumulative. It has been the author’s observation that some patients who receive a series of IV injections become progressively healthier. In these patients, the interval between treatments can be gradually increased, and eventually the injections are no longer necessary.Other patients require regular injections for an indefinite period of time in order to control their medical problems. This dependence on IV injections could conceivably result from any of the following: (1) a genetically determined impairment in the capacity to maintain normal intracellular nutrient concentrations;11 (2) an inborn error of metabolism that can be controlled only by maintaining a higher than normal concentration of a particular nutrient; or (3) a renal leak of a nutrient. 12 In some cases, continued IV therapy may be necessary because a disease state is too advanced to be reversible.