The excretion of large vitamin C loads in young and elderly subjects: an ascorbic acid tolerance test

Neutrophils are immune cells preferentially targeted by retinoic acid in elderly subjects

Background

The immune system gradually deteriorates with age and nutritional status is a major factor in immunosenescence. Of the many nutritional factors implicated in age-related immune dysfunction, vitamin A may be a good candidate, since vitamin A concentrations classically decrease during aging whereas it may possess important immunomodulatory properties via its active metabolites, the retinoic acids. This prompted us to investigate the immune response induced by retinoids in adults and elderly healthy subjects. Before and after oral supplementation with 13cis retinoic acid (0.5 mg/kg/day during 28 days), whole blood cells were phenotyped, and functions of peripheral blood mononuclear cells (PBMC) and polymorphonuclear cells (PMN) were investigated by flow cytometry and ELISA tests.

Results

In both young adults (n = 20, 25 ± 4 years) and older subjects (n = 20, 65 ± 4 years), retinoic acid supplementation had no effect on the distribution of leukocyte subpopulations or on the functions of PBMC (Il-2 and sIl-2R production, membrane expression of CD25). Concerning PMN, retinoic acid induced an increase in both spontaneous migration and cell surface expression of CD11b in the two different age populations, whereas bactericidal activity and phagocytosis remained unchanged.

Conclusions

We demonstrated that retinoic acid induces the same intensity of immune response between adult and older subjects, and more specifically affects PMN functions, i.e. adhesion and migration, than PBMC functions.

Scurvy: a disease almost forgotten

BACKGROUND

Although much decreased in prevalence, scurvy still exists in industrialized societies. Few recent large studies have examined its pathogenesis, signs, and symptoms.

METHODS

After we diagnosed scurvy in a 77-year-old female patient in 2003, we conducted a retrospective records review to identify patients with scurvy treated between 1976 and 2002 at Mayo Clinic (Scottsdale, Arizona; Rochester, Minnesota; or Jacksonville, Florida). We also searched the English-language medical literature for published reports on scurvy.

RESULTS

In addition to our patient, seven of 11 patients whose records in the institutional database mentioned vitamin C deficiency were women. The age ranged from a neonate to 77 years (mean, 48 years). The most common associated causes were concomitant gastrointestinal disease, poor dentition, food faddism, and alcoholism. Vitamin or mineral deficiencies other than vitamin C deficiency were also found in our patients who had scurvy. The most common symptoms were bruising, arthralgias, or joint swelling. The most common signs were pedal edema, bruising, or mucosal changes. Four patients had vague symptoms of myalgias and fatigue without classic findings, and five had concomitant nutritional deficiencies. Follow-up available for six of 12 patients treated by vitamin C supplementation showed complete resolution of symptoms in five.

CONCLUSIONS

Patients with scurvy may present with classic symptoms and signs or with nonspecific clinical symptoms and an absence of diagnostically suggestive physical findings. Concomitant deficiency states occur not uncommonly. Taking a thorough dietary history and measuring serum ascorbic acid levels should be considered for patients with classic signs and symptoms, nonspecific musculoskeletal complaints, or other vitamin or mineral deficiencies.

Modulators of free radical activity in diabetes mellitus: role of ascorbic acid

Free radical mechanisms are increasingly being implicated in the pathogenesis of tissue damage in diabetes. Various sources of free radicals may modulate oxidative stress in diabetes, including non-enzymatic glycosylation of proteins and monosaccharide autooxidation, polyol pathway activity, indirect production of free radicals through cell damage from other causes, and reduced antioxidant reserve. Ascorbic acid, which may be a principal modulator of free radical activity in diabetes, is shown to be consumed, presumably through free radical scavenging, thus preserving levels of other antioxidants such as glutathione.

Disturbed handling of ascorbic acid in diabetic patients with and without microangiopathy during high dose ascorbate supplementation

Abnormalities of ascorbic acid metabolism have been reported in experimentally-induced diabetes and in diabetic patients. Ascorbate is a powerful antioxidant, a cofactor in collagen biosynthesis, and affects platelet activation, prostaglandin synthesis and the polyol pathway. This suggests a possible close interrelationship between ascorbic acid metabolism and pathways known to be influenced by diabetes. We determined serum ascorbic acid and its metabolite, dehydroascorbic acid, as indices of antioxidant status, and the ratio, dehydroascorbate/ascorbate, as an index of oxidative stress, in 20 matched diabetic patients with and 20 without microangiopathy and in 22 age-matched control subjects. Each study subject then took ascorbic acid, 1 g daily orally, for six weeks with repeat measurements taken at three and six weeks. At baseline, patients with microangiopathy had lower ascorbic acid concentrations than those without microangiopathy and control subjects (42.1 +/- 19.3 vs 55.6 +/- 20.0, p less than 0.01, vs 82.9 +/- 30.9 mumol/l, p less than 0.001) and elevated dehydroascorbate/ascorbate ratios (0.87 +/- 0.46 vs 0.61 +/- 0.26, p less than 0.01, vs 0.38 +/- 0.14, p less than 0.001). At three weeks, ascorbate concentrations rose in all groups (p less than 0.0001) and was maintained in control subjects (151.5 +/- 56.3 mumol/l), but fell in both diabetic groups by six weeks (p less than 0.01). Dehydroascorbate/ascorbate ratios fell in all groups at three weeks (p less than 0.0001) but rose again in the diabetic groups by six weeks (p less than 0.001) and was unchanged in the control subjects. Dehydroascorbate concentrations rose significantly from baseline in all groups by six weeks of ascorbic acid supplementation (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)