Effects of L-citrulline supplementation and watermelon consumption on longer-term and postprandial vascular function and cardiometabolic risk markers: A meta-analysis of randomized controlled trials in adults

Nitric oxide: Potential therapeutic target in Heat Stress-induced Multiple Organ Dysfunction

As climate change intensifies, urgent action is needed to address global warming and its associated health risks, particularly in vulnerable regions. Rising global temperature and increasing frequency of heatwaves present a hidden health risk, disrupting the body's temperature regulation and leading to severe consequences such as heat stress-induced multiple organ dysfunction (HS-MOD). Multiple organ injury triggered by heat stress involves complex molecular pathways such as nitric oxide dysregulation, inflammation, oxidative stress, mitochondrial dysfunction, calcium homeostasis disruption, and autophagy impairment that contribute to cellular damage. Understanding these molecular pathways is crucial for developing targeted therapeutic interventions to alleviate the impact of heat stress (HS). As we explore numerous therapeutic strategies, a remarkable molecule captures our attention: nitric oxide (NO). This colorless gas, mainly produced by nitric oxide synthase (NOS) enzymes, plays crucial roles in various body functions. From promoting vasodilation and neurotransmission to regulating the immune response, platelet function, cell signaling, and reproductive health, NO stands out for its versatility. Exploring it as a promising treatment for heat stress-induced multiple organ injury highlights its distinctive features in the journey towards effective therapeutic interventions. This involves exploring both pharmacological avenues, considering the use of NO donors and antioxidants, and non-pharmacological strategies, such as adopting nitrate-rich diets and engaging in exercise regimens. This review highlights the concept of heat stress, the molecular framework of the disease, and treatment options based upon some new interventions.

Metabolomics signatures of plant protein intake: effects of amino acids and compounds associated with plant protein on cardiometabolic health

PURPOSE OF REVIEW

An increase in the plant-based characteristics of the diet is now recommended for human and planetary health. There is growing evidence that plant protein (PP) intake has beneficial effects on cardiometabolic risk. However, proteins are not consumed isolated and the protein package (lipid species, fiber, vitamins, phytochemicals, etc) may contribute, besides the protein effects per se, to explain the beneficial effects associated with PP-rich diets.

RECENT FINDINGS

Recent studies have shown the potential of nutrimetabolomics to apprehend the complexity of both the human metabolism and the dietary habits, by providing signatures associated to the consumption of PP-rich diets. Those signatures comprised an important proportion of metabolites that were representative of the protein package, including specific amino acids (branched-chain amino acids and their derivates, glycine, lysine), but also lipid species (lysophosphatidylcholine, phosphatidylcholine, plasmalogens) and polyphenol metabolites (catechin sulfate, conjugated valerolactones and phenolic acids).

SUMMARY

Further studies are needed to go deeper in the identification of all metabolites making part of the specific metabolomic signatures, associated to the large range of protein package constituents and their effects on the endogenous metabolism, rather than to the protein fraction itself. The objective is to determine the bioactive metabolites, as well as the modulated metabolic pathways and the mechanisms responsible for the observed effects on cardiometabolic health.

The effects of acute arginine supplementation on neuroendocrine, metabolic, cardiovascular, and mood outcomes in younger men: a double-blind placebo controlled trial

Objectives:

Arginine is an amino-acid supplement and precursor for nitric-oxide synthesis, which affects various biologic processes. The objective of this study was to determine the effects of arginine supplementation on growth hormone (GH) and metabolic parameters.

Methods:

Thirty physically active, healthy men (age 18–39 y; body mass index: 18.5–25 kg/m²) were randomized in a double-blind, placebo-controlled, crossover trial. Arginine (10 g) and placebo (0 g) beverages were consumed after an overnight fast. Blood samples were collected at baseline and 1.5, 3.0, and 24 h after supplementation. The primary outcomes were serum GH and metabolomics. Also, amino acids, glucose, insulin, triacylglycerols, thyroid hormones, testosterone, cortisol, dehydroepiandrosterone, and mood state were assessed. Individuals with detectable increases in GH were analyzed separately (responders: n = 16; < 0.05 ng/mL at 1.5 h). Repeated-measure analyses of variance estimated the treatment effects at each timepoint.

Results:

Arginine levels increased at 1.5 h (146%) and 3.0 h (95%; P ≤ 0.001) and GH (193%) and thyroid-stimulating hormone (TSH; 10%) levels at 24 h (P < 0.05) after arginine versus placebo consumption. Arginine versus placebo increased glucose levels at 1.5 h (5%) and 3.0 h (3%; P ≤ 0.001). Arginine versus placebo did not affect other dependent measures, including mood state (P > 0.05), but changes in the urea, glutamate, and citric-acid pathways were observed. Among responders, arginine versus placebo increased GH at 1.5 h (37%), glucose at 1.5 h (4%) and 3.0 h (4%), and TSH at 24 h (9%; P < 0.05). Responders had higher levels of benzoate metabolites at baseline and 1.5 h, and an unknown compound (X-16124) at baseline, 1.5 h, and 24 h that corresponds to a class of gut microbes (P < 0.05).

Conclusions:

Arginine supplementation modestly increased GH, glucose, and TSH levels in younger men. Responders had higher benzoate metabolites and an unknown analyte attributed to the gut microbiome. Future studies should examine whether the increased prevalence of these gut microorganisms corresponds with GH response after arginine supplementation.