Low 25OH Vitamin D Blood Levels Are Independently Associated With Higher Amyotrophic Lateral Sclerosis Severity Scores: Results From a Prospective Study

Vitamin D and human health: evidence from Mendelian randomization studies

We summarized the current evidence on vitamin D and major health outcomes from Mendelian randomization (MR) studies. PubMed and Embase were searched for original MR studies on vitamin D in relation to any health outcome from inception to September 1, 2022. Nonlinear MR findings were excluded due to concerns about the validity of the statistical methods used. A meta-analysis was preformed to synthesize study-specific estimates after excluding overlapping samples, where applicable. The methodological quality of the included studies was evaluated according to the STROBE-MR checklist. A total of 133 MR publications were eligible for inclusion in the analyses. The causal association between vitamin D status and 275 individual outcomes was examined. Linear MR analyses showed genetically high 25-hydroxyvitamin D (25(OH)D) concentrations were associated with reduced risk of multiple sclerosis incidence and relapse, non-infectious uveitis and scleritis, psoriasis, femur fracture, leg fracture, amyotrophic lateral sclerosis, anorexia nervosa, delirium, heart failure, ovarian cancer, non-alcoholic fatty liver disease, dyslipidemia, and bacterial pneumonia, but increased risk of Behçet's disease, Graves' disease, kidney stone disease, fracture of radium/ulna, basal cell carcinoma, and overall cataracts. Stratified analyses showed that the inverse association between genetically predisposed 25(OH)D concentrations and multiple sclerosis risk was significant and consistent regardless of the genetic instruments GIs selected. However, the associations with most of the other outcomes were only pronounced when using genetic variants not limited to those in the vitamin D pathway as GIs. The methodological quality of the included MR studies was substantially heterogeneous. Current evidence from linear MR studies strongly supports a causal role of vitamin D in the development of multiple sclerosis. Suggestive support for a number of other health conditions could help prioritize conditions where vitamin D may be beneficial or harmful.

Dietary Intake of Micronutrients and Disease Severity in Patients with Amyotrophic Lateral Sclerosis

Vitamins and essential metals have been studied as potential risk and prognostic factors in amyotrophic lateral sclerosis (ALS). This study aimed to evaluate the prevalence of inadequate micronutrient intake in ALS patients, comparing subgroups according to the disease severity. Data were obtained from the medical records of 69 individuals. Assessment of disease severity was determined by the revised ALS Functional Scale (ALSFRS-R), using the median as the cutoff. The prevalence of inadequate micronutrient intake was estimated using the Estimated Average Requirements (EAR) cut-point method. The prevalence of inadequate vitamin D, E, riboflavin, pyridoxine, folate, cobalamin, calcium, zinc, and magnesium intake was considered severe. Patients with lower ALSFRS-R scores had lower intakes of vitamin E (p < 0.001), niacin (p = 0.033), pantothenic acid (p = 0.037), pyridoxin (p = 0.008), folate (p = 0.009) and selenium (p = 0.001). Therefore, ALS patients should be monitored regarding dietary intake of micronutrients essential in neurological processes.

Potential role of vitamin D levels in amyotrophic lateral sclerosis cognitive impairment

Cognitive impairment (CI) is common in amyotrophic lateral sclerosis (ALS): a keystone is identifying factors that could potentially modify the CI course. In recent years, vitamin D is becoming a potential modificatory factor for CI in many neurological disorders. This study aimed to highlight if vitamin D deficiency correlated with CI and clinical features in a cohort of ALS patients. We included 55 ALS patients with a neuropsychological evaluation (classified with the Strong Criteria) and a vitamin D dosage at the diagnosis. We also reviewed medical records and completed data for medical history, physical and neurological examination, and functional scales. At the diagnosis, 30 patients (54%) had CI. Most patients (82%) displayed low vitamin D levels (19.87 ± 9.80 ng/ml). Comparing the vitamin D level between patients with and without CI, we observed significantly lower values in the first group (15.8 ± 8.2 vs. 22.0 ± 9.7 ng/ml, p: 0.04). In the spinal female subgroup (n = 15), we found an inverse correlation between vitamin D and bizarreness score in the cognitive estimates test (r = 0.58; p: 0.04) and a positive correlation with the Corrected Raven's Standard Progressive Matrices (r = 0.53, p: 0.04). Conversely, in the bulbar female group, we observed a correlation with the corrected direct span (r = 0.84, p: 0.03). With the log-rank survival analysis, we found that the patients with vitamin D < 10 ng/ml had a shorter disease duration (Chi: 5.78, p: 0.02). Our results indicate that levels of vitamin D can influence the cognitive status of people living with ALS and that severe deficits might be an adverse prognostic survival factor.

Vitamin D in Neurological Diseases

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Dietary-Derived Essential Nutrients and Amyotrophic Lateral Sclerosis: A Two-Sample Mendelian Randomization Study

Previous studies have suggested a close but inconsistent relationship between essential nutrients and the risk of amyotrophic lateral sclerosis (ALS), and whether this association is causal remains unknown. We aimed to investigate the potential causal relation between essential nutrients (essential amino acids, essential fatty acids, essential minerals, and essential vitamins) and the risk of ALS using Mendelian randomization (MR) analysis. Large-scale European-based genome-wide association studies' (GWASs) summary data related to ALS (assembling 27,205 ALS patients and 110,881 controls) and essential nutrient concentrations were separately obtained. MR analysis was performed using the inverse variance-weighted (IVW) method, and sensitivity analysis was conducted by the weighted median method, simple median method, MR-Egger method and MR-PRESSO method. We found a causal association between genetically predicted linoleic acid (LA) and the risk of ALS (OR: 1.066; 95% CI: 1.011-1.125; p = 0.019). An inverse association with ALS risk was noted for vitamin D (OR: 0.899; 95% CI: 0.819-0.987; p = 0.025) and for vitamin E (OR: 0.461; 95% CI: 0.340-0.626; p = 6.25 × 10^-7). The sensitivity analyses illustrated similar trends. No causal effect was observed between essential amino acids and minerals on ALS. Our study profiled the effects of diet-derived circulating nutrients on the risk of ALS and demonstrated that vitamin D and vitamin E are protective against the risk of ALS, and LA is a suggested risk factor for ALS.

Amyotrophic lateral sclerosis (ALS) and the endocrine system: Are there any further ties to be explored?

Amyotrophic Lateral Sclerosis (ALS) belongs to the family of neurodegenerative disorders and is classified as fronto-temporal dementia (FTD), progressive muscular atrophy, primary lateral sclerosis, and pseudobulbar palsy. Even though endocrine dysfunction independently impacts the ALS-related survival rate, the complex connection between ALS and the endocrine system has not been studied in depth. Here we review earlier and recent findings on how ALS interacts with hormones a) of the hypothalamus and pituitary gland, b) the thyroid gland, c) the pancreas, d) the adipose tissue, e) the parathyroid glands, f) the bones, g) the adrenal glands, and h) the gonads (ovaries and testes). Of note, endocrine issues should always be explored in patients with ALS, especially those with low skeletal muscle and bone mass, vitamin D deficiency, and decreased insulin sensitivity (diabetes mellitus). Because ALS is a progressively deteriorating disease, addressing any potential endocrine co-morbidities in patients with this malady is quite important for decreasing the overall ALS-associated disease burden. Importantly, as this burden is estimated to increase globally in the decades to follow, in part because of an increasingly aging population, it is high time for future multi-center, multi-ethnic studies to assess the link between ALS and the endocrine system in significantly larger patient populations. Last, the psychosocial stress experienced by patients with ALS and its psycho-neuro-endocrinological sequelae, including hypothalamic-pituitaryadrenal dysregulation, should become an area of intensive study in the future.