‘Tis the season for coughing, sneezing and sniffling. Many of us have stocked our medicine cabinets with vitamins, minerals and herbal remedies to ward off or cure these nasty symptoms of the common cold. Zinc supplements are a particularly frequent treatment, because zinc is known to support immune function. But do zinc supplements actually work?
Zinc is thought to halt the replication of rhinoviruses, the most common cause of colds. A recent scientific analysis pooled data from previous studies that compared oral zinc treatments with placebo or no intervention. It was found that zinc had no significant effect on the severity of symptoms experienced, but zinc did shorten the duration of a cold by an average of 2.63 days in adults. Not all zinc formulations are equally effective, however. Only zinc acetate caused a statistically significant reduction in symptom duration. Zinc gluconate and zinc sulfate were not successful.
So if zinc can help kick a cold faster, how much should we take once we feel the beginnings of a sore throat and runny nose? The evidence says to start using zinc within one to two days after the onset of a cold, but researchers have yet to offer an optimal dose. In the analysis mentioned above, subjects took zinc acetate lozenges every 2-3 hours while awake until symptoms resolved. By my own estimations, this provided about 54-104 mg zinc daily.
Remember that more is not always better. Zinc lozenges may cause a bad taste in your mouth or even nausea. Taking too many, or popping mega-dose zinc tablets can be harmful. The safe upper limit of zinc is set at 40 mg daily. Exceeding this amount for an extended period of time can actually decrease immunity and cause low copper levels.
The bottom line? Zinc may help your body fight the common cold, but if you’re going to load up, do it for a maximum of 7-10 days and be wary of how much zinc you’re ingesting! Read labels and choose supplements or lozenges with zinc acetate (or zincum aceticum) as the main ingredient.
Q: My doctor recommended I take a calcium supplement. Which type do you suggest, and when is the best time of day to take it?
A: Calcium supplements come in two forms: calcium citrate or calcium carbonate. Calcium carbonate (e.g. Caltrate®, Viactiv®, Tums®) is cheaper than Calcium citrate (e.g. Citracal®), but research has shown that under normal circumstances, the two forms are equally absorbed and utilized by the body. The exception is in cases of reduced stomach acidity, which occurs often in the elderly or if you take medications that decrease gastric acid secretion. If this is the case, then calcium citrate is the way to go. Check the ingredient list on the back of supplements and multivitamins to know which form of calcium the product contains.
A few rules:
- Calcium carbonate products should be taken with meals.
- Calcium citrate products can be taken with food or on an empty stomach.
- Along with food and antacids, calcium supplements likely inhibit the absorption of medications intended to halt bone loss, such as Fosamax, Actonel or Didronel. After taking one of these drugs, wait at least 30 minutes before ingesting anything except plain water.
- Calcium may prevent iron absorption, so if you’re also on supplemental iron, space the two tablets several hours apart.
Healthy adults should aim for 1,000-1,200 mg elemental calcium per day. It’s important to buy a supplement that also contains vitamin D, which helps our body absorb calcium. The recommendation for vitamin D is set at 600 IU daily, but a number of researchers believe this number should even be doubled.
Let’s put things in perspective…One Caltrate®600+D tablet contains 600 mg calcium plus 400 IU of vitamin D. Daily goals can be met with two of these tablets daily. On the other hand, Citracal® Regular 250 mg + D contains 500 mg calcium and 400 IU vitamin D per serving, but a serving is 2 tablets! That means you would need to take 4 Citracal® tablets per day to meet the daily calcium requirement. Viactiv® flavoredchews each have 500 mg calcium and 500 IU vitamin D. Lastly, a single Tums® tablet contains 500 mg of calcium carbonate, but only 200 mg of that is elemental calcium. Bottom line? Be sure to read labels and, of course, inform your doctor of all vitamins, supplements and herbs you’re taking.
A severe B12 (cobalamin) deficiency will eventually result in anemia if uncorrected. Anemia refers to an insufficient number of healthy red blood cells, which impairs the ability of oxygen to be carried to your body’s tissues. Pernicious anemia – the type caused specifically by cobalamin deficiency – can gravely impair neurologic function. Subclinical deficiency is much more common, in which a low cobalamin level appears on a blood test, but has yet to cause anemia.
Recall from my previous post on vegetarian diets that absorption of vitamin B12 is dependent on intrinsic factor (IF), which is produced in the gut. Causes of deficiency include inadequate dietary intake and impaired intestinal malabsorption, possibly due to lack of IF or insufficient gastric acid secretion (as is the case in the elderly). If your blood labs do not improve after dietary manipulation or supplementation, speak with your doctor about other tests that can determine if your deficiency is related to malabsorption.
The severity of your B12 deficiency dictates the level of supplementation required. A B12 level less than 400 pg/mL may be cause for concern, but it’s all about lab value trends. Correction of vitamin B12 levels to within the acceptable range may simply require a daily multivitamin (that usually contains 6 µg per tablet). The recommended daily intake for American adults is 2.4 µg. Research shows that for people (like vegetarians) who have normal B12 absorption, doses greater than 5 µg per day exceed the binding capacity of IF and only a tiny fraction can be absorbed anyway.
On the other hand, a more critical deficiency may require several weeks of high-dose supplementation (e.g. 1,000 µg daily oral dose) to be taken under the direction of your doctor. Sublingual B12 supplements, which dissolve under your tongue, are very effective in delivering the nutrient directly to your bloodstream, similar to an injection. These oral supplements come in 1,000 or even 5,000 µg doses or more! “Mega-dosing,” however, is excessive for someone who is still only moderately low in B12. While no toxic level of B12 supplementation has been found to date, it’s always wise to stick with the lowest dose possible that will effectively achieve healthful results.