9 Types of Zinc Supplementation and Absorption

Zinc is a powerful immune nutrient known for its benefits for providing immune health support and inflammation reduction as well as for improving cold and respiratory symptoms, wound healing, acne reduction, and lowering the risk of age-related diseases. Research on atherosclerosis and diabetes mellitus suggests that zinc deficiency may contribute to low-grade systemic inflammation.

Even more popular at the moment is the role of zinc and the potential benefits against COVID-19. This is probably one of the reasons that's driving the demand on zinc related products. In a ConsumerLab survey of 9,647 people who use dietary supplements shows that the supplements which experienced the greatest growth in popularity in 2020 were those being promoted to prevent or treat infection with SARS-CoV-2, the coronavirus that causes COVID-19. Zinc supplements achieved the highest growth with 13.5% points.

Does zinc help treat COVID 19? In order to answer that question, there are many zinc studies underway and you can review the status of these trials on clinicaltrials.gov. As of March 2021, there are 19 studies that have been launched to investigate the benefits of Zinc against COVID-19.


Types of Zinc

There are several types of zinc supplements. Some, such as zinc picolinate, may be better absorbed, while zinc acetate may be more effective at shortening the duration of the common cold (SourceSource).

Supplements contain several forms of zinc, including zinc gluconate, zinc citrate and zinc picolinate. The percentage of elemental zinc varies by form. 

1. Chelated Zinc

This form of zinc has undergone a process called chelation, whereby the organic molecules have been given an electrical charge that allows them to positively attract the charged mineral (in this case zinc). This creates a temporary increase in the complexity and concentration of the mineral within the molecule.

In other words, each molecule packs more concentrations of zinc via a process of attaching the mineral to something else, such as an amino acid. The belief is that this helps the body better absorb the mineral. 

Zinc picolinate or zinc gluconate are formed when zinc is chelated to picolinic acid or gluconic acid, so the main difference between zinc gluconate and picolinate is what compound it is bound to.

2. Zinc Citrate

This type of zinc is made with citric acid. A study found that when given as a supplement without food, zinc citrate absorption was comparable with that of zinc gluconate, and higher than zinc oxide.

Zinc citrate is the zinc salt of citric acid. This compound is well-known as a dietary supplement that is useful in preventing zinc deficiency. Typically, we take this orally as a capsule or as a tablet.

However, due to the presence of zinc, this may have a metallic taste. However, taking a small amount of beverage after taking the tablet can avoid this unusual taste. Moreover, this treatment may irritate the digestive tract, resulting in an upset stomach. Another important side effect is, we may get flu-like symptoms including fever, sore throat, chills, etc.

Zinc citrate is the form that's most commonly used in dental hygiene products like toothpaste and mouthwash to fight plaque and gingivitis.

3. Zinc Gluconate

This is the most common over-the-counter zinc supplement that’s found in your local drug or health food store. It’s made with gluconic acid is often found in oral supplements, nasal zinc sprays or lozenges. A meta-analysis indicates that zinc gluconate lozenges were able to reduce cold duration 28 percent.

Zinc gluconate is the zinc salt of gluconic acid. We can find gluconic acid in natural sources, but for the preparation of the supplement, industries produce gluconic acid via the fermentation of glucose by Aspergillus niger or some species of fungi.

More importantly, this compound is used to treat a common cold. We can use it in lozenges to treat the cold symptoms. When considering the side effects of this compound, anosmia (loss of smell) is a reported side effect. However, this compound is relatively safe than other zinc supplements.

4. Zinc Picolinate

This chelated form of zinc salt is made with picolinic acid and is popular for oral use to reverse zinc deficiency. One study comparing the absorption of zinc picolinate, zinc citrate and zinc gluconate shows that there’s no significant change in any of these forms, but zinc picolinate did improve zinc absorption in humans.

5. Zinc Carnosine

Zinc Carnosine is a dipeptide of the amino acids beta-alanine and histidine. A prescription medicine in Japan used to heal ulcers at 75 mg twice daily, this type of zinc is said to be helpful for leaky gut and healing stomach issues. It has a reputation for being better than antibiotics at healing h. pylori, the bacteria said to be responsible for stomach ulcers.

Zinc carnosine (also known as polaprezinc; Promac; L-CAZ, or taken as a self-named supplement) is a common form of zinc supplementation and medication.

A prospective randomized clinical trial published in 2017 showed that when antibiotic treatment for H. pylori infection was combined with zinc carnosine - the eradication rate was improved without added toxicity (Ref). A smaller trial published in 1999 reflected similar findings (Ref).

Zinc carnosine can be an amazing piece of any gut repair program & it was fun to learn that it does much more too.

Heat shock proteins (HSPs) are groups of proteins that are involved in the body’s ability to respond to inflammation, immune challenges, and stress. Genes that code for HSPs are highly regarded as “longevity” genes - the more active, the better.

While Zinc may indirectly help HSP expression through the promotion of mucosal health (a healthy home for flora to bind and grow), zinc carnosine is also an antioxidant and may support HSP expression directly.

Zinc nor L-carnosine have not been shown to support HSP expression by themselves, but the combined chelate form of zinc carnosine does support HSP activity for reasons that are still unclear.

6. Zinc Orotate

Zinc orotate is zinc that has been chelated to orotic acid. The human body’s cellular membranes readily absorb this type of zinc. Research from Dr. Hans Nieper has found that orotate forms of zinc were more neutrally charged, as compared to other types of zinc. This allowed them to pass through the membranes of cells easily, leading to higher tissue concentrations of zinc. Zinc orotates contain many antioxidant properties that can protect your health while offering your cells the most readily-absorbable form of zinc on the market today.

7. Zinc Acetate

Another chemically-altered form of zinc, acetates are considered to be more absorbable than gluconate. This form of zinc, also known as zinc salt dihydrate and zinc diacetate, is created by adding acetic acid to zinc carbonate or zinc metal. This form may aid in reducing the duration of the common cold (PubMed), as well as offer relief for Wilson's disease, a genetic disorder whereby the body stores toxic levels of copper.

8. Zinc Oxide

This inorganic compound of zinc is most commonly used in topical ointments for addressing minor skin conditions such as burns and irritation. It is also a common ingredient in sunscreens. This type is a non-chelated, inorganic form of zinc. The results are mixed on body absorption and metabolism of this form of inorganic zinc.

9. Zinc Sulfate

Water-soluble and non-chelated, this is an inorganic form of zinc, and the results are mixed on the body absorption and metabolism.

What is the Difference Between Zinc Citrate, Zinc Picolinate and Zinc Gluconate?

According to the Beth Israel Lahey Health Winchester Hospital, a person supplementing with zinc will find their best options in the form of zinc citrate, zinc acetate and zinc picolinate because these absorb the best. Zinc gluconate is not among the top three, but it is absorbed better than zinc oxide. As far as cost goes, zinc sulfate is the lowest-cost option among the supplements.

One difference between zinc gluconate and picolinate is that zinc gluconate, along with zinc acetate, has antiviral properties. This makes it a good form for making lozenges and nasal gels that don't contribute to the amount of iron digested and absorbed by the body, but it can fight viruses infecting the nose and throat.

The Mayo Clinic explains that zinc-based lozenges and syrups can be effective if they are used within the first 24 hours of the sign of symptoms. However, be careful — use of intranasal zinc has been linked with the loss of smell.

Although different forms of zinc have different amounts of elemental zinc that can be used by the body, the National Institutes of Health explains that there is not enough research indicating whether there are any superior forms in terms of absorption, bioavailability or tolerability.

One older study — published in the June 1987 issue of Agents Actions — did look at the effectiveness of three forms of zinc supplement and may shed a little bit of light on choosing zinc glycinate versus picolinate. The study looked at only 15 healthy human subjects who were divided into four groups. Over the course of four weeks, the four groups were tested with zinc picolinate, zinc citrate, zinc gluconate or a placebo.

Based on the zinc measurements in their hair, urine, erythrocyte and serum both before and after, zinc picolinate was the only form to raise zinc levels, at least in the hair, urine and erythrocyte. 

Based on these results, it seems as if zinc picolinate is most likely to absorb into a person's body, and zinc gluconate is the least likely. In terms of zinc glycinate versus picolinate, the picolinate wins this one. Still, more research would be needed to know more about zinc glycinate versus picolinate, especially because this study was done so long ago.

Zinc Types and Elemental Zinc Amount: How much elemental Zinc is in the different zinc compounds

Different forms of zinc contain different amounts of elemental zinc, which refers to the weight of the zinc molecule by itself (Note: Most product labels tend to mark the elemental weight):
  • Zinc citrate is approximately 34% zinc by weight. For a dose of 50mg elemental zinc, take 146 mg zinc citrate. (Examine)
  • Zinc sulfate consists 23% of elemental zinc; thus, 220 mg of zinc sulfate contains 50 mg of elemental zinc (NIH).
  • Zinc gluconate is approximately 13% zinc by weight. For a dose of 50mg elemental zinc, take 385 mg zinc gluconate. (Examine)
  • Zinc monomethionine is approximately 21% zinc by weight. For a dose of 50mg elemental zinc, take 238 mg zinc monomethionine. (Examine)
  • Zinc picolinate (20% of elemental zinc) (Metabolics
  • Zinc ascorbate (15%) (Metabolics
  • Zinc chloride (48%) (Metabolics
  • Zinc carbonate (52%) (Metabolics
  • Zinc bisglycinate (25%) (Metabolics
  • Zinc oxide (80%) (FamilyPractice). Although the percentage of elemental zinc is high, do take note that zinc oxide is one of the least bioavailable form.
  • Zinc carnosine: The typical clinical oral dose is 150 mg/day, containing 34 mg zinc and 116 mg L-carnosine.

Key Takeaway

If you think a zinc supplement is right for you, talk to your doctor about which form you should take. This is especially important because zinc can interfere with your body's absorption of copper and iron, so you might need to supplement those minerals as well.

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