Nutritional Renaissance and Public Health Policy

Research strategies in nutrition in health and disease: The failure of mechanistic research

This paper critically evaluates different research methods in order to assess their value for establishing which dietary changes are most effective for protecting health and preventing disease. The evidence demonstrates that the combined use of observational studies (mainly cohort studies) and randomized controlled trials (RCTs) is the most successful strategy. Studies of the details of body mechanisms in health and disease (mechanistic research) is another commonly used research strategy. However, much evidence demonstrates that it is a far less successful strategy. In order to support the above conclusions research studies from the following areas are discussed: obesity and dietary fat; heart disease and saturated fat; the Mediterranean diet and cardiovascular disease; type 2 diabetes and dietary fiber; and cancer and micronutrients. While mechanistic research has a poor track record in nutrition, it has achieved some success in other areas of biomedical science. This is shown by examining the role of mechanistic research in the discovery of new drugs.

Beneficial short term effect of low protein diet on chronic kidney disease pro-gression in patients with chronic kidney disease stage G3a. A pilot study

INTRODUCTION

The effectiveness of a low protein diet (LPD) to delay the progression of chronic kidney disease (CKD) remains controversial. The questions persist regarding which LPD for which CKD patients? Our study aimed to investigate the role of LPD in selected patients with CKD stage G3a.

METHODS

Forty-seven selected patients (23 men, mean age 55 ± 12), in stage G3a of CKD (eGFR: 45-59 ml/min) were included in this prospective 12 months study with a recommended dietary protein intake (DPI) of 0.8 g/kg/day. The DPI was estimated from 24 h urinary urea nitrogen excretion (Maroni formula).  All patients were trained by dietitian-nutritionist and had one baseline control and three visits. The clinical data, blood pressure, diet-adherence, eGFR, albumin, cholesterol, hemoglobin, proteinuria, and BMI were analyzed.

RESULTS

According to the adherence to LPD, the patients were divided into Adherent group (AG, n =24, 51 %) with DPI of 0.75 ± 0.25 g/kg/day and non-Adherent group (NAG, n =23, 49 %) with DPI of 1.3 ± 0.31 g/kg/day. During the follow up the eGFR decreased from 57.68 ± 4.0 to 56.11 ± 4.8, and from 55.45 ± 7.0 to 52.46 ± 7.2 for AG and NAG, respectively. The real drop of eGFR after 12 months was 1.57 for AG and 2.99 ml/min for NAG. The difference was statistically significant (p <0.01).

CONCLUSION

Despite the significant percentage of non-adherent patients, our pilot study confirms the beneficial effect of LPD on CKD progression. Adherent patients in G3a stage protect more successfully their GFR compared with non-adherent patients after 12 months. CKD stages with mild reduction of GFR are more challenging for further clinical studies. HIPPOKRATIA 2018, 22(4): 178-182.