Zinc: an essential and unheralded nutrient

Anosmia after Intranasal Zinc Gluconate Use

Background

Zinc is an essential mineral. Beneficial zinc absorption takes place via enteral, parenteral, or cutaneous routes. However, direct application to the olfactory epithelium has been reported to cause loss of smell. Recently, intranasal zinc gluconate has been recommended as a treatment for the common cold. Severe posttreatment hyposmia and anosmia have been observed.

Methods

The case report of a typical patient is presented and analyzed in detail, followed by a series of patients with severe hyposmia or anosmia after the use of intranasal zinc gluconate.

Results

Although interindividual variation in drug response and drug effect is apparent, the severe hyposmia or anosmia appears to be long lasting or permanent in some cases. The mechanism of olfactory loss is thought to be the direct action of the divalent zinc ion on the olfactory receptor cell.

Conclusions

Zinc ions are toxic to olfactory epithelium. Reports of severe hyposmia with parosmia or anosmia have occurred after intranasal use of zinc gluconate.

Oxidative stress--implications, source and its prevention

Oxidative stress has been a major predicament of present day living. It has been the product of imbalance between the processes involved in free radical generation and their neutralization by enzymatic and non-enzymatic defence mechanisms. The oxidative stress has been contributed by numerous factors including heavy metals, organic compound-rich industrial effluents, air pollutants and changing lifestyle pattern focussing mainly on alcohol consumption, dietary habits, sun exposure, nuclear emissions, etc. The most common outcome of oxidative stress is the increased damage of lipid, DNA and proteins that resulted in the development of different pathologies. Among these pathologies, cancer is the most devastating and linked to multiple mutations arising due to oxidative DNA and protein damage that ultimately affect the integrity of the genome. The chemopreventive agents particularly nutraceuticals are found to be effective in reducing cancer incidences as these components have immense antioxidative, antimutagenic and antiproliferative potentials and are an important part of our dietary components. These secondary metabolites, due to their unique chemical structure, facilitate cell-to-cell communication, repair DNA damage by the downregulation of transcription factors and inhibit the activity of protein kinases and cytochrome P450-dependent mixed function oxidases. These phytochemicals, therefore, are most appropriate in combating oxidative stress-related disorders due to their tendency to exert better protective effect without having any distinct side effect.

Zinc in attention-deficit/hyperactivity disorder

OBJECTIVE

The aim of this study was to review the published evidence for a role of zinc nutrition in attention-deficit/hyperactivity disorder (ADHD).

METHOD

A computer literature search was supplemented by the authors' knowledge.

RESULTS

Numerous controlled studies report cross-sectional evidence of lower zinc tissue levels (serum, red cells, hair, urine, nails) in children who have ADHD, compared to normal controls and population norms. A few studies show correlations of zinc level with either clinical severity or a change thereof in response to stimulant or chemical challenge. Two placebo-controlled trials--one of zinc monotherapy, the other of zinc supplementation of methylphenidate--reported significant benefit. However, diagnostic procedures and sample representativeness were often not clear, and most such reports have come from countries and cultures with different diets and/or socioeconomic realities than are found in the United States (only one American sample in nine published reports). In particular, both positive clinical trials of zinc supplementation came from the Mid-East (Turkey and Iran), an area with suspected endemic zinc deficiency. The largest of these trials used zinc doses above the recommended upper tolerable limit and had a 2 in 3 dropout rate.

CONCLUSION

It is not clear how well the accumulating evidence for a possible role of zinc in ADHD applies to middle-class American children. However, the evidence appears strong enough to warrant further controlled study in well-diagnosed samples representative of the socioeconomic spectrum. Hypothesis-testing clinical trials are needed of this potential treatment that, if found effective, might become a relatively safe, cheap substitute for, or adjunct to, current treatments in some patients. At present, it should remain an investigational treatment.

Serum zinc correlates with parent- and teacher- rated inattention in children with attention-deficit/hyperactivity disorder

OBJECTIVE

The aim of this study was to explore the relationship of zinc nutrition to the severity of attention-deficit/hyperactivity disorder (ADHD) symptoms in a middle-class American sample with well-diagnosed ADHD. Previous reports of zinc in ADHD, including two positive clinical trials of supplementation, have come mainly from countries and cultures with different diets and/or socioeconomic realities.

METHOD

Children 5-10 years of age with DISC- and clinician-diagnosed ADHD had serum zinc determinations and parent and teacher ratings of ADHD symptoms. Zinc levels were correlated (Pearson's and multiple regression) with ADHD symptom ratings.

RESULTS

Forty-eight children (37 boys, 11 girls; 33 combined type, 15 inattentive) had serum zinc levels with a median/mode at the lowest 30% of the laboratory reference range; 44 children also had parent/teacher ratings. Serum magnesium levels were normal. Nutritional intake by a parent-answered food frequency questionnaire was unremarkable. Serum zinc correlated at r = -0.45 (p = 0.004) with parent-teacher-rated inattention, even after controlling for gender, age, income, and diagnostic subtype, but only at r = -0.20 (p = 0.22) with CPT omission errors. In contrast, correlation with parent-teacher-rated hyperactivity-impulsivity was nonsignificant in the opposite direction.

CONCLUSION

These findings add to accumulating evidence for a possible role of zinc in ADHD, even for middle-class Americans, and, for the first time, suggest a special relationship to inattentive symptoms. They do not establish either that zinc deficiency causes ADHD nor that ADHD should be treated with zinc. Hypothesis-testing clinical trials are needed.

Importância do zinco na nutrição humana

Recentes pesquisas experimentais e clínicas têm reforçado a importância do zinco na saúde humana. O zinco possibilita várias funções bioquímicas, pois é componente de inúmeras enzimas, dentre estas, álcool desidrogenase, superóxido dismutase, anidrase carbônica, fosfatase alcalina e enzimas do sistema nervoso central. Participa na divisão celular, expressão genética, processos fisiológicos como crescimento e desenvolvimento, na transcrição genética, na morte celular, age como estabilizador de estruturas de membranas e componentes celulares, além de participar da função imune e desenvolvimento cognitivo. Sua deficiência pode causar alterações fisiológicas como, hipogonodismo, danos oxidativos, alterações do sistema imune, hipogeusia, danos neuropsicológicos e dermatites. Assim, devido a inúmeras pesquisas referentes a este mineral, este trabalho teve como objetivo mostrar os aspectos atuais sobre a essencialidade do zinco na nutrição humana.