The average height of American women is between 5-foot-1 and 5-foot-4. According to a study by the Imperial College of London, which used biometric data collected from 18-year olds around the world between 1914 and 2014, the tallest men in the world are Dutch and the tallest women are Latvian. Americans, who were once among the world's tallest people, are no longer even in the top 10. In fact, men from the US come in at number 37 and women rank number 42. But there may be some hope–for females at least.
Researchers at the University of Bonn found that while an increase in protein intake had no effect on the height of boys and young men, a correlation was found in the girls. Indeed, 7 grams above the daily protein intake recommendation could be the key to gaining one centimeter.
The researchers recorded protein intake from dietary survey data and also by measuring urinary urea nitrogen excretion in 189 healthy girls and boys.
First author Yifan Hua and Thomas Remer, PhD, evaluated dietary records, regular 24-hour urine collections and specific height measurements of children and adolescents from age 3 onward at the DONALD Study Center Dortmund of the University of Bonn (DOrtmund Nutritional and Anthropometric Longitudinally Designed Study).
The findings, published in Journal of Clinical Endocrinology and Metabolism, found that an increase in protein intake had no effect on body height of the males, but it did impact the females. The researchers’ calculations suggest that an average increase of about seven grams of protein daily above the intake recommendations yields a height increase of one centimeter on average. Remer noted that if added height is not wanted, females may be able to reduce their height later on by a few centimeters during growth by lowering their protein intake.
"The study is the first to demonstrate the anabolic potency of the essential nutrient protein by examining detailed nutritional data over a period from age 3 to 17," explained Remer.
Irrelevant to males
"This effect on height does not seem to play a relevant role in boys with protein intakes above requirements," said Hua. "Apparently, for them, significantly stronger effects of sex hormones - including testosterone - on the growth hormone axis leave less room for an additional anabolic nutritional effect from protein."
The researchers added that daily protein intake for children is often considerably higher in many cases. "Possible long-term consequences of correspondingly high protein intakes have not yet been satisfactorily examined," said Remer. "Only for bone stability have we been able to observe positive relations with increased protein intake in past studies, provided that the fruit and vegetable intake was not too low and thus the diet-dependent acid load was not too high."
“Our prospective, biomarker-confirmed findings on habitual protein intake during the pediatric period provide evidence that protein ingestion above dietary recommendation contributes to an enhanced adult height in girls. This enhancement, in turn, may be weakened by an insufficient alkalizing potential through a PRAL-raising fruit- and vegetable-poor nutrition,” the authors concluded.
Source: Journal of Clinical Endocrinology and Metabolism
“Adult stature and protein intake during childhood and adolescence from 3 years onward”
Authors: Y. Hua et al.