If zinc hasn’t been on your radar before, then it likely is now because its significant immune-supportive benefits* have been in the news a lot lately – including in our own Take 5 Daily. Articles on how to supplement with zinc and how zinc benefits immune function have appeared in recent months.

Zinc is not just for immune support either. In fact, zinc is in every cell in our bodies and is necessary as a co-factor in more than 200 enzymatic reactions.* A sampling of zinc’s key functions include the following:

  • White blood cell production (to make natural killer cells, T-lymphocytes, and B-lymphocytes) for support of a healthy immune response*
  • Testosterone production*
  • Skin health and wound healing*
  • Eye health, particularly the macula*
  • Normal growth and development*
  • Taste and smell*

Mineral absorption

When it comes to taking a mineral supplement, there are several things to consider to maximize your supplementation. The primary goal is to absorb the greatest amount of the mineral from the fewest number of capsules and with no side effects. So, how is this best accomplished?

The form of the mineral – including the compound it is bound to – matters. One factor that is always an issue when supplementing minerals is that, by their very nature, minerals are not particularly well absorbed by the human body. In addition, various dietary, lifestyle, and health factors can have a negative impact on mineral absorption.

For example, oxalic acid (found in high amounts in spinach, rhubarb, and black tea), phytic acid (found in whole grains, nuts, seeds, beans, and potatoes), caffeine, antacids, acid-blocking medications, and malabsorption syndromes, can all decrease the body’s ability to absorb minerals.

The obstacle to absorption can be overcome by optimizing the form the mineral comes in. This is simple chemistry – certain forms of minerals are better absorbed than others. 

To read more about why we choose certain mineral forma in general, you can check out this blog article: Get the most out of mineral supplementation.

Research shows superior absorption with a zinc chelate in the form of zinc bisglycinate

Zinc bisglycinate – a well-tolerated and well-absorbed zinc chelate – is comprised of one zinc molecule bound to two (bis = two) molecules of the amino acid glycine. Because this form of zinc is absorbed intact (that is, bound to glycine) it does not compete with other minerals for absorption in the intestinal tract. Several studies demonstrate its superior absorption.

A small crossover study examined the absorption of 15 mg of zinc as bisglycinate or gluconate in 12 healthy volunteers. A single dose of each was followed by a 7-day washout period, then followed by a dose of the other form. Zinc bisglycinate resulted in 43-percent higher zinc blood levels compared to zinc gluconate.1

 

In another comparative absorption study, 30 healthy females were randomly assigned (10 in each group) to: (1) zinc bisglycinate (60 mg of elemental zinc), (2) zinc gluconate (60 mg of elemental zinc), or (3) a maltodextrin placebo – all daily for six weeks..

Participants who took the zinc bisglycinate had significant increases in blood levels of zinc compared to the zinc gluconate and placebo groups. Zinc bisglycinate resulted in significant increases in blood levels of zinc in all 10 subjects, while 6 of 10 women in the zinc gluconate group had no significant increase or even had a decrease in zinc blood levels.2

And in a third study, 12 healthy women were given single doses of zinc bisglycinate, zinc picolinate, zinc gluconate, or zinc oxide. With blood levels being tested every hour for four hours, zinc bisglycinate resulted in the highest plasma zinc levels. In addition, zinc in red blood cells (RBC) was measured over the same 4-hour period. At the end of the study, RBC levels of zinc were in this order from highest to lowest: zinc bisglycinate > zinc picolinate > zinc gluconate > zinc oxide.

Better absorption means better efficacy and tolerability

Obviously, the more of a mineral you absorb into your bloodstream, the less of it that ends up in your stool, and the greater the opportunity for it to do its work in your body. This is demonstrated in a study of mineral differences in exercise performance.4 A double-bind, placebo-controlled trial looked at the effect of three different protocols in 42 aerobically fit women (ages 18-30).

Aerobic fitness was tested before and after one month of three test protocols: (1) 36 mg of iron (as ferrous sulfate), 15 mg zinc (as zinc gluconate), 2 mg copper (as copper gluconate), 2 grams of carnitine (as Carnipure®), and 400 mg of phosphatidylserine (SerinAid®); or (2) 36 mg iron (as iron bisglycinate; Ferrochel®), 15 mg of zinc (as zinc bisglycinate), 2 mg copper (as copper bisglycinate) – the bisglycinates all from Albion®, 2 grams of carnitine (as Carnipure), and 400 mg of phosphatidylserine (SerinAid); or (3) placebo corn starch. The only differences between the test material in groups 1 and 2 were the differences in mineral forms – group 2 taking all mineral chelates as bisglycinates. 

After one month on the test protocols, the women in the group who took bisglycinate chelate minerals showed significantly decreased 3-mile run time and significantly further 25-minute stationary bike distance compared to baseline (before supplementation) and compared to the other two groups.

In most instances, the better that a mineral is absorbed, the fewer the side effects, which are often GI symptoms such as constipation or diarrhea. In the case of zinc, whatever its form, it’s best to take it with food because zinc is notorious for causing nausea on an empty stomach, although in the studies cited above, zinc bisglycinate was well-tolerated.

Explore Thorne’s zinc supplement offerings.


References

  1. Gandia P, Bour D, Maurette J-M, et al. A bioavailability study comparing two oral formulations of zinc (Zn bis-glycinate vs. Zn gluconate) after a single administration to twelve healthy female volunteers. Int J Vitamin Nutr Res 2007;77(4):243-248.
  2. DiSilvestro R, Koch E, Rakes L. Moderately high dose zinc gluconate or zinc bisglycinate: effects on plasma zinc and erythrocyte superoxide dismutase in young adult women. Biol Trace Elem Res 2015;168(1):11-14.
  3. DiSilvestro R, Swan M. Comparison of four commercially available zinc supplements for performance in a zinc tolerance test. FASEB J 2008;22:693.3.
  4. DiSilvestro R, Hart S, Marshall T, et al. Enhanced aerobic exercise performance in women by a combination of three mineral chelates plus two conditionally essential nutrients. J Int Soc Sports Nutr 2017;14:42.