Phosphorus Supplementation Mitigated Food Intake and Growth of Rats Fed a Low-Protein Diet

Abstract

Background: Low protein intake is associated with various negative health outcomes at any life stage. When diets do not contain sufficient protein, phosphorus availability is compromised because proteins are the major sources of phosphorus. However, whether mineral phosphorus supplementation mitigates this problem is unknown, to our knowledge. Objective: Our goal was to determine the impact of dietary phosphorus supplementation on food intake, weight gain, energy efficiency, body composition, blood metabolites, and liver histology in rats fed a low-protein diet for 9 wk. Methods: Forty-nine 6-wk-old male Sprague-Dawley rats were randomly allocated to 5 groups and consumed 5 isocaloric diets ad libitum that varied only in protein (egg white) and phosphorus concentrations for 9 wk. The control group received a 20% protein diet with 0.3% P (NP-0.3P). The 4 other groups were fed a low-protein (10%) diet with a phosphorus concentration of 0.015%, 0.056%, 0.1%, or 0.3% (LP-0.3P). The rats' weight, body and liver composition, and plasma biomarkers were then assessed. Results: The addition of phosphorus to the low-protein diet significantly increased food intake, weight gain, and energy efficiency, which were similar among the groups that received 0.3% P (LP-0.3P and NP-0.3P) regardless of dietary protein content. In addition, phosphorus supplementation of low-protein diets reduced plasma urea nitrogen and increased total body protein content (defatted). Changes in food intake and efficiency, body weight and composition, and plasma urea concentration were highly pronounced at a dietary phosphorus content <0.1%, which may represent a critical threshold. Conclusions: The addition of phosphorus to low-protein diets improved growth measures in rats, mainly as a result of enhanced energy efficiency. A dietary phosphorus concentration of 0.3% mitigated detrimental effects of low-protein diets on growth parameters.

Daily energy expenditure in rats following structured exercise training is affected by dietary phosphorus content

“…Our results are in line with others, as studies in animals have shown that diets deficient in P are associated with a lower food intake and weight gain (31) . Besides, a comparable rising trend in food intake and EEf was previously demonstrated when P was increased gradually from very low to standard P level of 0.3%, which can be related to the capability of young animals to regulate their food intake in order to support their nutritional requirements for growth and maintenance (30) . However, at higher intakes of P (˃0.3%P), food intake was shown to be inconsistent among different studies.…”

“…The Harvard University (USA) software (http://hedwig.mgh.harvard.edu/sample_size/size.html) was used to determine sample size. The sample size for two groups was calculated using input parameters as follows: α error probability of 0•05, power probability of 0•08, 1.5 or 25% difference between the means based on previously determined weight gain data (6.0 ±0.95 g/d) (30) . As a result a total of sample size of 8 rats per group was obtained.…”

Possible role of available phosphorus in potentiating the use of low-protein diets for broiler chicken production

“… Hammoud et al. (2017) observed that feeding a low-protein diet (10% vs. a control diet at 20%) to rats significantly retarded growth but that these deleterious effects could be largely offset by increasing dietary phosphorus content, both in growth rate and also in body composition.…”

Effect of phosphorus supplementation on food intake and growth rate of rats maintained on gluten diet

“….We have recently found that the addition of phosphorus to a low protein diet (10 % egg white protein) in rats was able to attain a weight gain comparable to that of a normal protein diet (20 %) (3) . Therefore, a study was conducted to investigate whether phosphorus addition can affect growth of rats maintained on incomplete protein diet.…”

“…For that reason, it should be complemented with a protein source containing the limiting amino acid to match human needs ( 1 ) . Further, wheat is known to contain limited amounts of available phosphorus ( 2 ) .We have recently found that the addition of phosphorus to a low protein diet (10 % egg white protein) in rats was able to attain a weight gain comparable to that of a normal protein diet (20 %) ( 3 ) . Therefore, a study was conducted to investigate whether phosphorus addition can affect growth of rats maintained on incomplete protein diet.…”