the low-carbohydrate diet. As these studies demonstrated, there will obviously be a decrease in
nutrient intake if a subject decreases caloric intake from 1900 to 1400 (39). The question
therefore is whether a 1400 calorie ketogenic diet is more or less nutritionally complete than a
1400 calorie balanced diet.
On an absolute level, small decreases in thiamine, nicotinic acid, calcium and iron were
noted while there were increases in vitamin D and riboflavin. When compared on a relative scale
(amount of nutrient per 1000 calories), nutrient intake was actually higher on the low-
carbohydrate diet (39). It should be noted that the diet studied was higher in carbohydrate
(averaging 67 grams per day) than most ketogenic diets and contained milk. This provides only a
limited model for a diet containing 30 grams of carbohydrate or less per day.
Another study examining nutrient intake of a ketogenic diet at 2100 calories found the
ketogenic diet to provide greater than the RDA for Vitamin A, Vitamin C, riboflavin, niacin, and
phosphorous. There were deficiencies in thiamine, Vitamin B-6, folacin, calcium, magnesium,
iron, zinc and fiber (38).
It should be noted that current research into optimal health and prevention of diseases
focuses on nutrients in vegetables called phytonutrients, which appear to play a protective role in
many diseases. The limited vegetable intake on a ketogenic diet means that these nutrients will
not be consumed to any appreciable degree. This once again points to the fact that the ketogenic
diet should probably not be used long term (unless indicated for medical reasons), or that
individuals on a ketogenic diet should use their small carbohydrate allowance to maximize
vegetable intake.
Due to its restrictive nature, the ketogenic diet can be deficient in certain nutrients.
However this is no different than any other calorically restricted diet in that any reduction in food
intake will result in a reduction in nutrient intake. At the very minimum, a basic multi-
vitamin/mineral (providing at least the RDA for all nutrients) should be taken daily to avoid
deficiencies. Depending on the intake of dairy foods such as cheese, a calcium supplement may
be warranted. Specific nutrients, especially electrolytes are discussed in the next section.
Electrolyte excretion/Death
The diuretic (dehydrating) nature of ketosis causes an excretion of three of the body’s
primary electrolytes: sodium, potassium, and magnesium (31,40). These three minerals are
involved in many processes in the body, one of which is the regulation of muscle contraction,
including the heart. Some studies show a net loss of calcium while others do not (31).
A severe loss of electrolytes is problematic. At the least, it can cause muscle cramping,
which is often reported by individuals on a ketogenic diet. At the extreme, it can compromise
normal heart function.
During the late 1970’s, a large number of deaths occurred in individuals following a 300
calorie per day liquid ketogenic diet called “The Last Chance Diet” (41-43). This diet relied on a
processed protein as its only source of calories and the protein, which was a hydrolyzed collagen
protein with the amino acid tryptophan added to it, contained no vitamins or minerals. As well,
mineral supplements were not given or suggested to individuals on the diet.