History of scurvy and use of vitamin C in critical illness: A narrative review

Structure, mechanism, and evolution of the last step in vitamin C biosynthesis

Photosynthetic organisms, fungi, and animals comprise distinct pathways for vitamin C biosynthesis. Besides this diversity, the final biosynthetic step consistently involves an oxidation reaction carried out by the aldonolactone oxidoreductases. Here, we study the origin and evolution of the diversified activities and substrate preferences featured by these flavoenzymes using molecular phylogeny, kinetics, mutagenesis, and crystallographic experiments. We find clear evidence that they share a common ancestor. A flavin-interacting amino acid modulates the reactivity with the electron acceptors, including oxygen, and determines whether an enzyme functions as an oxidase or a dehydrogenase. We show that a few side chains in the catalytic cavity impart the reaction stereoselectivity. Ancestral sequence reconstruction outlines how these critical positions were affixed to specific amino acids along the evolution of the major eukaryotic clades. During Eukarya evolution, the aldonolactone oxidoreductases adapted to the varying metabolic demands while retaining their overarching vitamin C-generating function.

The evidence to date: implications of l-ascorbic acid in the pathophysiology of aging

L-Ascorbic acid, commonly known as vitamin C, has been used not only for disease prevention and in complementary and alternative medicine, but also for anti-aging purposes. However, the scientific evidence is not yet sufficient. Here, we review the physiological functions of vitamin C and its relationship with various pathological conditions, including our previous findings, and discuss the prospects of its application in healthy longevity. In summary, vitamin C levels are associated with lifespan in several animal models. Furthermore, clinical studies have shown that the blood vitamin C levels are lower in middle-aged and older adults than in younger adults. Lower blood vitamin C levels have also been observed in various pathological conditions such as chronic kidney disease and chronic obstructive pulmonary disease in the elderly. These observations suggest the implications of vitamin C in age-related pathological mechanisms owing to its physiological functions.

Vitamin C regulates skeletal muscle post-injury regeneration by promoting myoblast proliferation through its direct interaction with the Pax7 protein

Previous studies have shown that vitamin C (VC), an essential vitamin for the human body, can promote the differentiation of muscle satellite cells (MuSCs) in vitro and play an important role in skeletal muscle post-injury regeneration. However, the molecular mechanism of VC regulating MuSC proliferation has not been elucidated. In this study, the role of VC in promoting MuSC proliferation and its molecular mechanism were explored using cell molecular biology and animal experiments. The results showed that VC accelerates the progress of skeletal muscle post-injury regeneration by promoting MuSC proliferation in vivo. VC can also promote skeletal muscle regeneration in the case of atrophy. Using the C2C12 myoblast murine cell line, we observed that VC also stimulated cell proliferation. In addition, after an in vitro study establishing the occurrence of a physical interaction between VC and Pax7, we observed that VC also upregulated the total and nuclear Pax7 protein levels. This mechanism increased the expression of Myf5 (Myogenic Factor 5), a Pax7 target gene. This study establishes a theoretical foundation for understanding the regulatory mechanisms underlying VC-mediated MuSC proliferation and skeletal muscle regeneration. Moreover, it develops the application of VC in animal muscle nutritional supplements and treatment of skeletal muscle-related diseases.

Severe vitamin C deficiency associated with continuous renal replacement therapy: A case report

Hypovitaminosis C is prevalent in critically ill patients. Continuous renal replacement therapy (CRRT) clears vitamin C, increasing the risk for vitamin C deficiency. However, recommendations for vitamin C supplementation in critically ill patients receiving CRRT vary widely, from 250 mg/day to 12 g/day. This case report describes a patient who developed a severe vitamin C deficiency after prolonged CRRT despite receiving ascorbic acid (450 mg/day) supplementation in her parenteral nutrition. This report summarizes recent research investigating vitamin C status in critically ill patients receiving CRRT, discusses the patient case, and provides recommendations for clinical practice. In critically ill patients receiving CRRT, the authors of this manuscript suggest providing at least 1000 mg/day of ascorbic acid to prevent vitamin C deficiency. Baseline vitamin C levels should be checked in patients who are malnourished and/or have other risk factors for vitamin C deficiency, and vitamin C levels should be monitored thereafter every 1-2 weeks.

Significance of Vitamin Supplementation in Reducing the Severity of COVID-19

Coronavirus disease-19 (COVID-19), a serious pandemic due to the SARS-CoV-2 virus infection, caused significant lockdowns, healthcare shortages, and deaths worldwide. The infection leads to an uncontrolled systemic inflammatory response causing severe respiratory distress and multiple-organ failure. Quick development of several vaccines efficiently controlled the spread of COVID-19. However, the rise of various new subvariants of COVID-19 demonstrated some concerns over the efficacy of existing vaccines. Currently, better vaccines to control these variants are still under development as several new subvariants of COVID-19, such as omicron BA-4, BA-5, and BF-7 are still impacting the world. Few antiviral treatments have been shown to control COVID-19 symptoms. Further, control of COVID-19 symptoms has been explored with many natural and synthetic adjuvant compounds in hopes of treating the deadly and contagious disease. Vitamins have been shown to modulate the immune system, function as antioxidants, and reduce the inflammatory response. Recent studies have investigated the potential role of vitamins, specifically vitamins A, B, C, D, and E, in reducing the immune and inflammatory responses and severity of the complication. In this brief article, we discussed our current understanding of the role of vitamins in controlling COVID-19 symptoms and their potential use as adjuvant therapy.

Scurvy presenting as difficulty in walking in a child

Scurvy, a disease caused by ascorbic acid (vitamin C) deficiency, is a rare disease in the modern world. We report a case of a boy in middle childhood, with a background of autism, presenting bed-bound due to progressive bilateral lower limb pain, with concomitant rashes, bleeding gums and worsening lethargy. Detailed dietary history revealed a severely restricted diet. Physical examination showed bilateral lower limb ecchymoses, perifollicular hemorrhages, perifollicular hyperkeratosis and cockscrew hairs which are pathognomonic features of scurvy. A low serum ascorbic acid level confirmed the diagnosis. Therapy with oral vitamin C supplement and rehabilitation with multidisciplinary care was successful, with complete resolution of symptoms. This case emphasises the importance of thorough dietary evaluation in children with autism and food selectivity presenting with non-specific symptoms. Physician awareness of nutritional deficiencies avoids unnecessary extensive investigations and sub-specialty referrals and translates to savings in medical expenses.

The Role of Nutrition in Pathogenesis of Uterine Fibroids

Uterine fibroids are benign tumors that arise from the smooth muscle tissue of the uterus and are the most common tumors in women. Due to their high prevalence, costs for the health care system and the substantial impact on women's quality of life, they are a significant public health concern. Previous literature on the impact of diet on the occurrence, growth and symptoms of fibroids is limited. Recently, many papers have been written on this topic. A scoping review of PubMed and Cochrane databases was performed using the following keywords: uterine fibroids, antioxidants, diet, diet, vegetarian, vegetables, fruits, meat and soy foods, dairy products, tea, vitamin D, vitamin C, ascorbic acid. Preliminary research has shown a beneficial effect of vegetable and fruit consumption on the occurrence of fibroids. A relationship between hypovitaminosis D and an increased risk of fibroids has also been demonstrated. Studies on epigallocatechin gallate showed its apoptosis-promoting and antifibrinolytic effect in fibroid cells. Initial results are promising, but further randomized trials are needed to draw firm conclusions about the effects of diet and nutrients on uterine fibroids.

Assessment of nutrient adequacy in undergraduate students during the undertaking shipboard internship: using 12-day dietary recall through smartphone photography

BACKGROUND

This study aimed to investigated nutritional status and estimated the adequacy of dietary intake of university students during shipboard internships.

METHODS

In this cross- sectional study, data were collected from 25 students out of 42 participants who attended in the research information session in the department of maritime at a university located in Jeonbook, South Korea. The dietary intake data was obtained using the 12-day dietary recall through smartphone photography during the shipboard internships. The data on dietary intake were used to calculate acceptable macronutrient distribution ranges (AMDRs), frequency of inappropriate intake of the 2020 Dietary Reference Intakes for Koreans (KDRIs) as a reference, intake ratio to the nutrient adequacy ratio (NAR), mean adequacy ratio (MAR), and index of nutritional quality (INQ).

RESULTS

The average age of subjects was 21.68 years and average BMIs in men and women were 25.67 kg/m2 and 23.44kg/m2, respectively. The average energy of men and women was 2018.66 kcal and 1727.87 kcal, respectively. More than half of the subjects did not meet the inappropriate range of the AMDRs for carbohydrates and fat. The NAR of vitamin A, vitamin C, and calcium among all 10 nutrients tended to be lower in both men and women. The MAR were 0.71 and 0.769. On the other hand, in both men and women, vitamin C had the lowest INQ (0.5 and 0.39). For men, grains and potatoes were the major contributors to energy and carbohydrates, and calcium contributed in the order of meat, fish and eggs and vegetables and fruits. Although the highest contributors to energy and carbohydrates for women were grains and potatoes, the contributions from meat, fish, and eggs were similar, and the major contributors to calcium were vegetables and fruits.

CONCLUSIONS

To improve the inadequate nutritional status of university students engaged in shipboard internships with the aim of pursuing careers as seafarers, there is a need to provide additional nutritional education tailored to their specific circumstances. Additionally, professional health guidance should be provided to maintain optimal nutritional status.

Intravenous vitamin C monotherapy in critically ill patients: a systematic review and meta-analysis of randomized controlled trials with trial sequential analysis

BACKGROUND

A recent landmark randomized controlled trial (RCT) in septic patients demonstrated an increased risk of death and persistent organ dysfunction with intravenous Vitamin C (IVVC) monotherapy, which represents a disparate result from previous systematic reviews and meta-analyses (SRMA). We performed an updated SRMA of IVVC monotherapy to summarize and explore heterogeneity across current trials and conduct trial sequential analysis (TSA) to guard against type-I or type-II statistical errors.

METHODS

RCTs evaluating IVVC in adult critically ill patients were included. Four databases were searched from inception to 22 June 2022 without language restrictions. The primary outcome was overall mortality. Random effect meta-analysis was performed to estimate the pooled risk ratio. TSA for mortality was performed using the DerSimonian-Laird random effect model, alpha 5%, beta 10%, and relative risk reduction (RRR) of 30%, 25%, and 20%.

RESULTS

We included 16 RCTs (n = 2130). IVVC monotherapy is associated with significant reduction in overall mortality [risk ratio (RR) 0.73, 95% confidence interval (CI) 0.60-0.89; p = 0.002; I² = 42%]. This finding is supported by TSA using RRR of 30% and 25%, and sensitivity analysis using fixed-effect meta-analysis. However, the certainty of our mortality finding was rated low using GRADE due to the serious risk of bias and inconsistency. In a priori subgroup analyses, we found no differences between single vs multicenter, higher (≥ 10,000 mg/day) vs lower dose and sepsis vs non-sepsis trials. Post-hoc, we found no differences in subgroup analysis of earlier (< 24 h) vs delayed treatment, longer (> 4 days) vs shorter treatment duration, and low vs other risk of bias studies. IVVC may have the greatest benefit in trials that enrolled patients above (i.e., > 37.5%; RR 0.65, 95% CI 0.54-0.79) vs below (i.e., ≤ 37.5%; RR 0.89, 95% CI 0.68-1.16) median control group mortality (test for subgroup differences: p = 0.06), and TSA supported this.

CONCLUSIONS

IVVC monotherapy may be associated with mortality benefits in critically ill patients, particularly in patients with a high risk of dying. Given the low certainty of evidence, this potentially life-saving therapy warrants further studies to identify the optimal timing, dosage, treatment duration, and patient population that will benefit most from IVVC monotherapy. PROSPERO Registration ID: CRD42022323880. Registered 7th May 2022.

[Vitamin C and D supplementation in critically ill patients]

Micronutrient supplementation as part of the medical nutrition therapy for critically ill patients has received much attention in the past few years. Nevertheless, in clinical practice uncertainty remains about the optimal supplementation strategy, including which substance at which dosage should be administered at what time to specific groups of patients. Thus, the aim of this narrative review is to summarize the current evidence and recommendations for the micronutrients vitamin C and vitamin D. The physiological and pathophysiological roles of both vitamins are presented, recently published clinical trials are discussed, and the recommendations of the current guidelines are summarized. In addition, pragmatic tips for use in everyday clinical practice in the intensive care unit are given.

An update of the effects of vitamins D and C in critical illness

Many critically ill patients are vitamin D and vitamin C deficient and the current international guidelines state that hypovitaminoses should be compensated. However, uncertainty about optimal dosage, timing and indication exists in clinical routine, mainly due to the conflicting evidence. This narrative review discusses both micronutrients with regards to pathophysiology, clinical evidence of benefits, potential risks, and guideline recommendations. Evidence generated from the most recent clinical trials are summarized and discussed. In addition, pragmatic tips for the application of these vitamins in the clinical routine are given. The supplementations of vitamin D and C represent cost-effective and simple interventions with excellent safety profiles. Regarding vitamin D, critically ill individuals require a loading dose to improve 25(OH)D levels within a few days, followed by a daily or weekly maintenance dose, usually higher doses than healthy individuals are needed. For vitamin C, dosages of 100-200 mg/d are recommended for patients receiving parenteral nutrition, but needs may be as high as 2-3 g/d in acutely ill patients.