Relationships between minerals' intake and blood homocysteine levels based on three machine learning methods: a large cross-sectional study

BACKGROUND

Blood homocysteine (Hcy) level has become a sensitive indicator in predicting the development of cardiovascular disease. Studies have shown an association between individual mineral intake and blood Hcy levels. The effect of mixed minerals' intake on blood Hcy levels is unknown.

METHODS

Data were obtained from the baseline survey data of the Shanghai Suburban Adult Cohort and Biobank(SSACB) in 2016. A total of 38273 participants aged 20-74 years met our inclusion and exclusion criteria. Food frequency questionnaire (FFQ) was used to calculate the intake of 10 minerals (calcium, potassium, magnesium, sodium, iron, zinc, selenium, phosphorus, copper and manganese). Measuring the concentration of Hcy in the morning fasting blood sample. Traditional regression models were used to assess the relationship between individual minerals' intake and blood Hcy levels. Three machine learning models (WQS, Qg-comp, and BKMR) were used to the relationship between mixed minerals' intake and blood Hcy levels, distinguishing the individual effects of each mineral and determining their respective weights in the joint effect.

RESULTS

Traditional regression model showed that higher intake of calcium, phosphorus, potassium, magnesium, iron, zinc, copper, and manganese was associated with lower blood Hcy levels. Both Qg-comp and BKMR results consistently indicate that higher intake of mixed minerals is associated with lower blood Hcy levels. Calcium exhibits the highest weight in the joint effect in the WQS model. In Qg-comp, iron has the highest positive weight, while manganese has the highest negative weight. The BKMR results of the subsample after 10,000 iterations showed that except for sodium, all nine minerals had the high weights in the joint effect on the effect of blood Hcy levels.

CONCLUSION

Overall, higher mixed mineral's intake was associated with lower blood Hcy levels, and each mineral contributed differently to the joint effect. Future studies are available to further explore the mechanisms underlying this association, and the potential impact of mixed minerals' intake on other health indicators needs to be further investigated. These efforts will help provide additional insights to deepen our understanding of mixed minerals and their potential role in health maintenance.

Risk Factors for Cardiovascular Disease in Patients Undergoing Peritoneal Dialysis

Patients on peritoneal dialysis (PD) are at high cardiovascular risk. Although some risk factors are unmodifiable (for example, age, sex, genetics), others are exacerbated in the unfriendly uremic milieu (inflammation, oxidative stress, mineral disturbances) or contribute per se to kidney disease and cardiovascular progression (diabetes mellitus, hypertension). Moreover, several factors associated with PD therapy may both increase (by altered lipid profile, hyperinsulinemia, and formation of advanced glycation end-products) and decrease (by better blood pressure control and anemia management) cardiovascular risk. The present review discusses recent findings and therapy trends in cardiovascular research on the PD population, with emphasis on the roles of inflammation, insulin resistance, homocysteinemia, dyslipidemia, vascular calcification, and genetics/epigenetics.

Assessing Plasma Total Homocysteine in Patients with End-Stage Renal Disease

Elevated plasma total homocysteine (tHcy) is a risk factor for cardiovascular disease; however, in light of several recent randomized trials, the issue of causality has been cast into doubt. Patients with end-stage renal disease are particularly interesting as they consistently have elevated tHcy and their leading causes of morbidity and mortality are related to cardiovascular disease. In the present article, we review the early evidence for the homocysteine theory of atherosclerosis, homocysteine metabolism, mechanisms of toxicity, and pertinent available clinical investigations. Where appropriate, the sparse evidence of homocysteine in peritoneal dialysis is reviewed. We conclude by addressing the difficulties associated with lowering plasma tHcy in patients with end-stage renal disease and suggest some novel methods for lowering tHcy in this resistant population. Finally, to address the issue of causality, we recommend that clinicians and scientists await the results of the FAVORIT trial before abandoning homocysteine as a modifiable risk factor for cardiovascular disease, as this study has recruited patients from a population with consistently elevated plasma tHcy who are known to respond to vitamin therapy.

Water soluble vitamins and peritoneal dialysis - State of the art

This review presents the results of a systematic literature search concerning water soluble vitamins and peritoneal dialysis modality. We provide an overview of the data available on vitamin requirements, dietary intake, dialysis related losses, metabolism and the benefits of supplementation. We also summarise the current recommendations concerning the supplementation of vitamins in peritoneal dialysis and discuss the safety of an administration of vitamins in pharmacological doses.

Cardiovascular risk in the peritoneal dialysis patient

Cardiovascular death is the most frequent cause of death in patients on peritoneal dialysis. Risk factors for cardiovascular death in these patients include those that affect the general population as well as those related to end-stage renal disease (ESRD) and those that are specific to peritoneal dialysis. The development of overhydration after loss of residual renal function is probably the most important cardiovascular risk factor specific to peritoneal dialysis. The high glucose load associated with peritoneal dialysis may lead to insulin resistance and to the development of an atherogenic lipid profile. The presence of glucose degradation products in conventional dialysis solutions, which leads to the local formation of advanced glycation end products, is also specific to peritoneal dialysis. Other risk factors that are not specific to peritoneal dialysis but are related to ESRD include calcifications and protein-energy wasting. When present together with inflammation and atherosclerosis, protein-energy wasting is associated with a marked increase in the risk of cardiovascular death. Obesity is not associated with increased cardiovascular risk in patients on any form of dialysis. Left ventricular hypertrophy and increased arterial stiffness are the most important risk factors for cardiovascular events in the general population.

Some old drugs improve late primary patency rate of native arteriovenous fistulas in hemodialysis patients

Vascular access failure causes 20% of all hospitalizations of dialysis patients. Native arteriovenous fistulas, the best type of dialysis vascular access, have a 1-year primary patency rate that is extremely variable, ranging 40-80%. Neointimal hyperplasia is the most important cause of arteriovenous fistula late primary dysfunction. In recent years the arteriovenous fistula late primary patency rate has not improved because of the increase of old uremic patients with a high number of comorbidities and the lack of new therapeutic interventions. Therefore, we performed a long-term case-control study to analyze which factors or drugs may affect native arteriovenous fistula late primary patency rate in 60 incident hemodialysis patients. The arteriovenous fistula late primary patency rate was 75.1% after 12 months, 58.5% after 24 months, and 50% after 987 days. Homocysteine levels during follow-up had a significant direct association with vascular access failure (event vs. event-free 28.5+/-1.9 vs. 22.3+/-1.2 micromol/L, p<0.01). Folate values had a trend toward an inverse relationship with arteriovenous fistula failure (event vs. event-free 11.5+/-1.2 vs. 14.6 vs. 1.1 ng/mL, p=0.06). Patients treated with folic acid and/or statin had an arteriovenous fistula late primary patency rate significantly higher than patients without folic acid and statin therapy, respectively, 81.7% vs. 66% after 1 year and 71.5% vs. 39.1% after 2 years (p=0.02). Many other factors were not associated with vascular access failure. Statin and homocysteine-lowering folic acid therapy is associated with prolonged arteriovenous fistula survival. It is important to perform randomized trials to verify our observation.

Homocysteine-Lowering Vitamin B Treatment Decreases Cardiovascular Events in Hemodialysis Patients

BACKGROUND

Dialysis patients have higher cardiovascular events rate than patients with normal renal function. Hyperhomocysteinemia, a risk factor for cardiovascular disease, is frequently detected in dialysis patients. Vitamin B supplementation lowers hyperhomocysteinemia, but it is unknown whether it reduces cardiovascular events rate. We planned a long-term study to analyze the effects of homocysteine-lowering vitamin B therapy on cardiovascular disease in hemodialysis patients.

METHODS

We performed a single center open prospective trial. Patients, just on folate therapy at enrolment, were left out from randomization and maintained folate therapy according to study's protocol (group A). Patients, untreated with folic acid at recruitment, were randomly assigned to other 2 groups: patients submitted to folate supplementation according to study's protocol (group B), and untreated ones (group C). We instructed patients to take 5 mg oral daily folic acid or 5 mg every other day whether serum folate levels were up the normal high limit. We measured homocysteine, folate and vitamin B12 plasma levels at baseline and every 4 months. We chose the appearance of fatal and nonfatal cardiovascular events as end-points.

RESULTS

We analyzed data of 114 patients for a median follow-up time of 871 days. Stepwise regression analysis demonstrated that baseline homocysteine levels were related to folate (coefficient: -1.02; F: 64.5), creatinine (coefficient: 0.98; F: 11.3), and C reactive protein (coefficient: -0.64; F: 4.3). Patients ended the study for the following reasons: cardiovascular morbidity (n = 44), death (n = 25), renal transplant (n = 9), moved away (n = 4). Cardiovascular events occurred in 58 of 114 patients (51%), in 26 of 63 (41%) treated patients (both group A and group B) and in 32 of 51 (63%; chi2 = 6.0; p = 0.05) untreated patients (group C). Kaplan-Meier survival analysis showed that cardiovascular events were less frequent in treated patients with low homocysteine levels (chi2 24.1; p < 0.0001). Cox regression analysis showed that cardiovascular events were explained by homocysteine, dialysis vintage, past cardiovascular accidents, and age. We noticed not only lower homocysteine levels, but also higher protein catabolic rate values in events-free patients as compared with patients with nonfatal cardiovascular events. After having divided patients into 4 subgroups according to high and low, split at median, Hcy and protein catabolic rate values, we observed in Kaplan-Meier survival curves for cardiovascular events by these subgroups that patients with low Hcy and high protein catabolic rate values showed a significant lower hazard rate than patients with high Hcy and low protein catabolic rate levels (chi2 = 21.7; p < 0.0001).

CONCLUSIONS

This trial shows for the first time that homocysteine-lowering folate therapy decreases cardiovascular events in dialysis patients. It is necessary to perform large prospective studies to confirm our results.

Adequate range for sulfur-containing amino acids and biomarkers for their excess: lessons from enteral and parenteral nutrition

The adequacy range of dietary requirements of specific amino acids in disease states is difficult to determine. In health, several techniques are available allowing rather precise quantification of requirements based on growth of the organism, rises in plasma concentration, or increases in the oxidation of marker amino acids during incremental administration of the amino acid under study. Requirements may not be similar in disease with regard to protein synthesis or with regard to specific functions such as scavenging of reactive oxygen species by compounds including glutathione. Requirements for this purpose can be assessed only when such a function can be measured and related to clinical outcome. There is apparent consensus concerning normal sulfur amino acid (SAA) requirements. WHO recommendations amount to 13 mg/kg per 24 h in healthy adults. This amount is roughly doubled in artificial nutrition regimens. In disease or after trauma, requirements may be altered for methionine, cysteine, and taurine. Although in specific cases of congenital enzyme deficiency, prematurity, or diminished liver function, hypermethionemia or hyperhomocysteinemia may occur, SAA supplementation can be considered safe in amounts exceeding 2-3 times the minimal recommended daily intake. Apart from some very specific indications (e.g., acetaminophen poisoning), the usefulness of SAA supplementation is not yet established. There is a growing body of data pointing out the potential importance of oxidative stress and resulting changes in redox state in numerous diseases including sepsis, chronic inflammation, cancer, AIDS/HIV, and aging. These observations warrant continued attention for the potential role of SAA supplementation. In particular, N-acetylcysteine remains promising for these conditions.

Randomized trial of FX high flux vs standard high flux dialysis for homocysteine clearance

BACKGROUND

Cardiovascular disease is the major cause of death in the end-stage renal disease population. Novel risk factors such as homocysteine (Hcy) are of considerable interest in this group as hyperhomocysteinaemia is highly prevalent in the setting of renal impairment. Folic acid-vitamin B group therapies are only partially effective treatments. Hcy is highly protein-bound and thus poorly dialysed. Dialyzers with albumin-leaking properties have been shown to result in lowering of plasma Hcy. As the FX-class (Advanced Fresenius Polysulfone dialyzer) has greater clearance of larger molecular weight substances but is non-albumin-leaking, we explored the capacity of this new technology membrane to reduce plasma Hcy levels.

METHODS

A prospective randomized cross-over trial in 35 prevalent haemodialysis patients, one group receiving 12 weeks dialysis using FX dialyzer then 12 weeks with standard high flux dialysis (SHF) and the other group SHF followed by FX dialyzer. All patients received vitamin B(6) 25 mg and folic acid 5 mg daily throughout the study.

RESULTS

The primary outcome was plasma Hcy pre-dialysis at week 12. FX vs SHF showed no significant difference, 25+/-6.6 vs 25.9+/-5.8 microg/l, Delta95% CI = -2.77 to 4.59, P = 0.31. There was a non-significant trend toward a decrease in Hcy in both groups (27.43+/-7.68 to 25.91+/-5.78 micromol/l for SHF, P = 0.23 and 26.0+/-4.58 to 25.0+/-6.61 micromol/l for FX, P = 0.28). Analysis by repeated measures method demonstrated a statistically significantly lower Hcy with FX vs SHF dialyzer (adjusted beta = -1.30, 95% CI = -2.41 to -0.19, P = 0.022). K(t)/V(urea) was higher in FX vs SHF (1.35+/-0.18 vs 1.22+/-0.2; P = 0.013). Folate and B(6) levels did not change.

CONCLUSIONS

The primary outcome analysis did not show any significant difference in pre-Hcy comparing FX and SHF membranes. Although our secondary analysis demonstrated a statistically significant difference between membranes, the magnitude of the difference (1.3 mumol/l) is not clinically significant. Thus the use of the FX dialyzer did not result in a clinically significant benefit in relation to improving pre-dialysis Hcy compared with standard high-flux dialysis.