In April 2019 researchers from the UK published their review of the medical scientific literature to assess nutrient intake of low carbohydrate diets. A total of 10 studies were involved in the review. It was noted that only one study included the use of multivitamin supplements. Dietary intake was reported over 2 to 104 weeks, with weight losses ranging from 2 to 9 kg. Although no nutritional deficiencies were reported, the intake of thiamine, folate, magnesium, calcium, iron, and iodine was seen to decrease by 10-70% following the start of a low carbohydrate diet. Individuals on the Atkins diet showed inconsistent changes in vitamin A, E, and β-carotene intakes, whilst individuals on the Paleolithic diet reported increases in these micronutrients. However, it shoud be noted that an increase in individuals with iodine deficiency was reported in those using the Paleolithic diet (15% of individuals rising to 73% after a 6 months period). The researchers concluded by stating that micronutrients in foods and/or supplements should be considered when designing, prescribing or following low carbohydrate diets.
Churuangsuk C et al. Impacts of carbohydrate-restricted diets on micronutrient intakes and status: A systematic review. Obes Rev. 2019 Apr 22. [Epub ahead of print]