Abstract
High-carbohydrate (HC) diets and low-carbohydrate ketogenic diets (LCKD) are consumed by athletes for body composition and performance benefits. Little research has examined nutrient density of self-selected HC or LCKDs and consequent effect on blood haematology in an athlete population. Using a non-randomised control intervention trial, nutrient density over 3 days, total blood count and serum ferritin, within endurance athletes following a self-selected HC (n = 11) or LCKD (n = 9) over 12 weeks, was examined. At week 12, HC diet participants had greater intakes of carbohydrate, fibre, sugar, sodium, chloride, magnesium, iron, copper, manganese and thiamine, with higher glycaemic load (GL), compared to LCKD participants (P < 0.05). LCKD participants had greater intakes of saturated fat, protein, a higher omega 3:6 ratio, selenium, vitamins A, D, E, K1, B12, B2, pantothenic acid and biotin. Mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) decreased in LCKD participants after 12 weeks but remained unchanged in HC participants, with no change in serum ferritin in either group. This analysis cannot examine nutrient deficiency, but athletes should be made aware of the importance of changes in dietary type on micronutrient intakes and blood haematology, especially where performance is to be considered.
Highlights
The low-carbohydrate ketogenic diets (LCKD) has emerged as a popular method for decreasing body mass in overweight patients [1], improving body composition in athletic populations [2,3,4] and has been examined in terms of exercise performance effects [5,6,7]
Examination of nutrient density within endurance athletes who adhered to a HC or LCKD revealed consumption of a HC diet resulted in greater intakes of fibre, sugar, sodium, chloride, magnesium, iron, copper, manganese and thiamine, with higher glycaemic load (GL), compared to LCKD consumption
Irrespective of dietary approach, endurance athletes should be made aware of the dangers of low iron and encouraged to monitor blood work with a medical professional
Summary
The LCKD has emerged as a popular method for decreasing body mass in overweight patients [1], improving body composition in athletic populations [2,3,4] and has been examined in terms of exercise performance effects [5,6,7]. Despite the broad range of research examining its effects in non-athletic and athletic populations, little research has examined the micronutrient density of an LCKD. A recent review by Churuangsut et al [13] reported reduced intakes of thiamine, folate, magnesium, calcium, iron and iodine upon consumption of carbohydrate-restricted diets, but no study reviewed was classed as “ketogenic”. Several trials presented within the review [13] were weight loss trials, so decreased micronutrient consumption was expected.
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