Changes in Iron Status During Weight Loss
For several decades, very-low-energy diets
(VLEDs) have been used by obese individuals to achieve weight loss. During
the weight loss, patients often have dramatic drops in circulating thyroid
hormone concentrations and experience cold intolerance. Because poor iron
status is known to alter thermogenesis, we investigated the possibility
that iron intake interacts with energy intake during weight loss in obese
individuals. The effects on indicators of iron and thyroid status of increasing
the iron content of a very-low-energy diet from 18 to 27 mg/d during 12
wk of a very-low-energy diet were compared with the effects on the same
indicators of increasing energy intake from 1752 kJ(420 kcal) to 3347
kJ(800 kcal)/d. Although all very-low-energy diet groups initially had
30 percent declines in plasma transferrin saturation, increases in plasma
ferritin concentrations, and decreases in plasma thyroid hormone concentrations,
patients who received iron supplementation had significantly higher circulating
concentrations of triiodothyronine and thyroxine at the end of the very-low-energy
diet than did patients who received only the recommended dietary allowance
of iron. The patients who received iron supplementation also had a more
rapid return of iron indicators to normal values over the course of the
very-low-energy diet. The transitory fall in iron delivery to bone marrow
was not associated with anemia. These data suggest that higher thyroid
hormone concentrations can be maintained during very-low-energy diets
that provide higher iron intakes.
Source: Beard J, Borel M, Peterson FJ.
Nutrition Department, Pennsylvania State University, University Park 16803,
USA. 1997
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