Quote from Dr. Garrett Smith on November 7, 2018, 5:48 pm

Vitamin A: potential misclassification of vitamin A status among patients with type 2 diabetes and hypertension in urban Ghana

https://academic.oup.com/ajcn/article/102/1/207/4564255
"Background:  Serum retinol—a VAD marker—increases in kidney disease and decreases in inflammation, which can partly be attributed to alterations in the vitamin A–transport proteins retinol-binding protein 4 (RBP4) and prealbumin. Kidney dysfunction and inflammation commonly accompany T2D and hypertension.

Objective: Among urban Ghanaians, we investigated the associations of T2D and hypertension with serum retinol as well as the importance of kidney function and inflammation in this regard.

Design: A hospital-based, case-control study in individuals for risk factors of T2D, hypertension, or both was conducted in Kumasi, Ghana (328 controls, 197 with T2D, 354 with hypertension, and 340 with T2D plus hypertension). In 1219 blood samples, serum retinol, RBP4, and prealbumin were measured. Urinary albumin and estimated glomerular filtration rate (eGFR) defined kidney function. C-reactive protein (CRP) >5 mg/L indicated inflammation. We identified associations of T2D and hypertension with retinol by linear regression and calculated the contribution of RBP4, prealbumin, urinary albumin, eGFR, and CRP to these associations as the percentages of the explained variance of retinol.

Results: VAD (retinol <1.05 μmol/L) was present in 10% of this predominantly female, middle-aged, overweight, and deprived population. Hypertension, but not T2D, was positively associated with retinol (β: 0.12; 95% CI: 0.08, 0.17), adjusted for age, sex, socioeconomic factors, anthropometric measurements, and lifestyle. In addition to RBP4 (72%) and prealbumin (22%), the effect of increased retinol on individuals with hypertension was mainly attributed to impaired kidney function (eGFR: 30%; urinary albumin: 5%) but not to inflammation."

Translation:  More Poison/"Vitamin A", higher blood pressure.

For this next one, remember that the body generally wants to keep levels of Retinol Binding Protein and serum retinol (aka Poison/"Vitamin A") as close as possible.  See the Rules thread in this forum for more info.

Elevated serum retinol-binding protein 4 levels are correlated with blood pressure in prehypertensive Chinese

https://www.nature.com/articles/jhh201744

"Retinol-binding protein 4 (RBP4) has been reported involving in the occurrence and development of hypertension. However, to date, few data are available on the correlation between serum RBP4 level and blood pressure (BP) in prehypertension. Therefore, this association was investigated in prehypertensive Chinese. Overall, 160 subjects with prehypertension (Pre-HT group) and 160 subjects with normal BP (NBP group) were recruited in this study. The subjects were divided into the following four subgroups according to body mass index (BMI): obese Pre-HT subgroup; non-obese Pre-HT subgroup; obese NBP subgroup; and non-obese NBP subgroup (n=80 in each). Anthropometric parameters, systolic BP (SBP), diastolic BP (DBP) and several biochemical parameters were measured. Fasting insulin was evaluated by radioimmunoassay. Serum RBP4 level was measured by enzyme-linked immunosorbent assay. The Pre-HT group had higher levels of serum RBP4 level than did the NBP group (P<0.001). Moreover, higher RBP4 levels were identified in the obese Pre-HT subgroup relative to the non-obese Pre-HT subgroup (P=0.005). However, no difference in RBP4 level was identified between the obese and the non-obese NBP subgroups (P=0.317). RBP4 level was positively correlated with BMI, SBP, and DBP after adjustment for age, sex, smoking status and alcohol consumption. The results of the multiple regression analyses demonstrated that RBP4 level was independently associated with SBP and DBP. In conclusion, serum RBP4 level was significantly higher and closely associated with BP in prehypertensive Chinese."

Let me summarize the above:

Higher RBP4 = higher retinol = higher Poison/"Vitamin A" = higher systolic blood pressure (SBP) = higher diastolic blood pressure (DBP) = higher BMI (generally fatter people).