Assessment of micronutrients in a 12-wk ketogenic diet in obese adults.

OBJECTIVE

A 12-wk ketogenic diet was found to have many beneficial effects in healthy obese adults, but it is not clear if the supply of micronutrients is adequate.

METHODS

In 35 adult individuals with body mass index >30, the intakes of minerals and their serum levels were analyzed at baseline and at weeks 4 and 12 of the ketogenic diet intervention. The intake of vitamins and serum antioxidative potential were also investigated.

RESULTS

Throughout the diet the intakes of magnesium, calcium, iron, phosphorus, and potassium were less than recommended values, but serum levels always remained within the reference range. Nevertheless, the level of calcium decreased significantly (from 2.52 ± 0.10 mmol/L at baseline to 2.36 ± 0.07 mmol/L at week 12, P < 0.001), which could be due to the omission of legumes and reduced dairy intake or because of the high fat intake alone. The levels of phosphate increased concomitantly. Calcium serum levels were negatively associated with ω-6 but not with ω-3 unsaturated fatty acid intake. The intakes of water-soluble vitamins were also too low. However, the antioxidative potential of serum did not change during intervention.

CONCLUSIONS

Careful choice of foods that will provide the necessary micronutrients is of utmost importance when consuming ketogenic diet. In the 12 wk study the decreased intakes were not reflected in serum values, but special attention to calcium should be advised if such diet is recommended for longer periods.