Minerals/Vitamins

Zinc Shown to Reduce Cold Symptoms

The most frequent cause of the common cold is rhinovirus infection, although as many as 200 other viruses may be responsible for the condition. U.S. adults and children suffer from 2-6 colds per year, with substantial loss of work resulting and no proven treatment identified.

The authors of this study note 10 previous controlled trials on treatment of the common cold with zinc lozenges.

n those trials, five reported that zinc lozenges reduced the duration of cold symptoms. The remaining five showed no effect of zinc on cold symptoms, although the authors of the current study suggest that inappropriate zinc lozenge preparations in these latter five studies may have caused the results observed.

In this study, 50 volunteers were recruited within 24 hours of developing symptoms of the common cold. They were administered one zinc lozenge (12.8 mg zinc acetate) or placebo every two to three hours as long as they experienced symptoms. Symptom scores for sore throat; nasal discharge and congestion; sneezing; cough; scratchy throat; hoarseness; muscle ache; fever; and headache were recorded daily for 12 days.

Administration of zinc lozenges reduced duration and severity of cold symptoms compared with placebo. Duration of cold symptoms was 4.5 days in the zinc group vs. 8.1 days in the placebo group; cough duration was 3.1 days vs. 6.3 days; and nasal discharge was 4.1 days vs. 5.8 days. Overall, severity scores for all symptoms were reduced with zinc administration compared to placebo. The authors note that plasma levels of zinc increased and plasma levels of proinflammatory cytokines decreased, suggesting that zinc's influence on cytokines may account for improvements in clinical cold symptoms.

Calcium, Magnesium, Potassium, and Stroke Risk

Hypertension is a strong risk factor for stroke. Evidence that mineral intake, specifically calcium, potassium and magnesium, may help regulate blood pressure suggests that these minerals could also play a role in preventing or reducing the risk of stroke.

In a study involving 85,764 women (34-59 years of age and free of diagnosed cardiovascular disease or cancer), subjects completed dietary questionnaires from which calcium, potassium and magnesium intakes were calculated.

These questionnaires were administered every two years for 15 years, during which time newly diagnosed major illnesses or events (including stroke) were identified and recorded.

Results revealed 690 incident cases of stroke; women with high calcium, potassium and magnesium intake over the course of the study period showed a reduced incidence of stroke compared with women with lower average intake of these minerals. The association was particularly strong with respect to magnesium intake after adjusting for other cardiovascular risk factors.

Interestingly, further adjustment for potassium and magnesium suggested an independent association of calcium with stroke risk, although intakes 600 mg/day did not appear to reduce the risk of stroke further, and the increase in risk was limited to the lowest intake group.

This is a well-executed study; however, clinicians should consider the authors warning that women in this group may have had unknown characteristics predisposing them to stroke. 

Calcium vs. Colorectal Adenomas

Health care professionals and much of the general public are aware that a diet rich in vegetables and fruits is associated with lower risk of colorectal cancer. They also know that eating too much animal fat and red meat seems to increase risk.

This study aimed at identifying what role calcium might play in the biological mechanisms underlying how such cancer may be caused or prevented.

This was a randomized, double-blind trial of 930 subjects (mean age 61; 72% men) with a recent history of colorectal adenomas. The subjects received either calcium carbonate or a placebo daily and got follow-up colonoscopies one year and four years later. Results showed that those who received calcium supplements had a lower incidence of recurrence of adenomas. The results were consistent with epidemologic data and are supported by a large body of experimental data on humans and animals.

Conclusions: Taking calcium carbonate may significantly-though moderately-reduce the risk of recurrent colorectal adenomas. And since the toxicity of this simple and inexpensive supplement is minimal and it may have other benefits (such as reducing the risk of osteoporosis), "its risk-benefit balance may be favorable." 

Do Zinc Lozenges Reduce Cold Symptoms?

No consistently effective therapy for the common cold has been well-documented, but evidence suggests that several possible mechanisms may make zinc an effective option. This study of 100 patients presenting with symptoms of the common cold tested the reliability of zinc lozenges in reducing the duration of cold-related symptoms.

Patients received one lozenge every two hours containing either 13.3 mg of zinc from zinc gluconate, or 5% calcium lactate pentahydrate (placebo).

The average time to complete resolution of symptoms was significantly shorter in the zinc group than in the placebo group (4.5 days compared with 7.5 days). The zinc group experienced significantly fewer days with coughing (2.0 days compared with 4.5 days), headache (2.0 days vs. 3.0 days), hoarseness (2.0 days vs. 3.0 days), nasal drainage (4.0 days vs. 7.0 days), and sore throat (1.0 days vs 3.0 days).

Patients in both the zinc and the calcium group experienced side effects (nausea, bad-taste reactions) from the lozenges; substantially more patients in the zinc group reported side effects than in the calcium group (90% vs. 62%). Doctors should take these potential side effects into consideration when recommending a course of care.