Comparing the Absorbability and Bioavailability of Zinc Supplements

 This article aims to help explain the complex processes of zinc absorption and bioavailability. 

The subject is covered in detail in some recent studies that compare their relative bioaccessibility. 

A study by Ośko J, Pierlejewska W, Grembecka in Nutrients journal found the highest bioaccessibility was found for zinc diglycinate and the lowest for zinc sulphate.

Another study suggests Zinc Picolinate is a highly absorbed form. It is chelated with picolinic acid, aiding in its efficient uptake by the digestive system.

Zinc Gluconate is commonly found in over-the-counter supplements and lozenges. While its absorption rate is reasonable, this study shows that complexing zinc with picolinic acid (Zinc Picolinate) helps absorption.

Lastly, Zinc Citrate is also a popular option, especially for those who prefer a form without the slightly metallic taste that other types may have. However, its absorption rate is typically lower than that of Zinc Picolinate.

Each form has its own advantages and disadvantages.

Comparing the Best Forms of Zinc for Absorption

When it comes to zinc supplements, one size certainly does not fit all. The form of zinc used in a supplement may make a significant difference in how well your body can absorb and utilize it.

How Zinc is Absorbed in the body

Skip this bit if you're not interested in the science. But for those who are, this is how zinc absorption works!

Zinc is absorbed in the small intestine, primarily in the jejunum and ileum. This process is facilitated by specialized proteins called zinc transporters. These transporters, such as ZIP4 and ZnT1, work to move zinc ions across the cellular membrane and into the enterocytes, the cells lining the intestine.

Once inside the enterocytes, zinc can be bound to metallothioneins, proteins that act as intracellular storage for zinc. This allows for a regulated release into the bloodstream, avoiding rapid fluctuations that could be detrimental. Subsequently, zinc is released into the portal vein, through which it reaches the liver for further distribution to various tissues and organs.

What Affects Zinc Uptake?

So what affects how well your body takes in zinc from food or supplements?

Age and physiological states

Age is a critical factor that affects zinc absorption.

Children, who are in a rapid state of growth, have increased needs for zinc and therefore have higher absorption rates.

Older adults, on the other hand, may experience reduced absorption due to age-related declines in digestive function.

Nutritional interactions

The nutrients present in the food matrix can also have a significant impact on zinc absorption. For example, phytic acid, which is commonly found in plant-based foods such as grains and legumes, can bind to zinc and inhibit its absorption.

On the other hand, amino acids like cysteine and methionine, which are often found in protein-rich foods, can form complexes with zinc that enhance its solubility and uptake.

Health conditions and medications

Certain health conditions can also adversely affect zinc absorption. 

Some medications may interfere with zinc uptake by altering the stomach's acidity or affecting mineral balance.

Some hormones have also been shown to impact zinc uptake. Insulin can modulate the expression of zinc transporters in the intestines, thereby influencing absorption efficiency.

If you have, or believe you may have any kind of health condition, you should consult a qualified health professional who can help you determine the best form of zinc is right for you.

 

Foods That Help or Hinder Zinc Uptake

Foods that help zinc absorption

• Protein-rich foods: Protein helps to increase the acidity of the stomach, which makes it easier for zinc to be absorbed. Good sources of protein include meat, poultry, fish, eggs, dairy products, and beans.
• Foods high in vitamin C: Vitamin C helps to break down phytates, a compound found in plant foods that can bind to zinc and prevent its absorption. Good sources of vitamin C include citrus fruits, berries, and tomatoes.
• Foods high in amino acids: Amino acids are the building blocks of protein. Some amino acids, such as cysteine and methionine, can help to increase zinc absorption. Good sources of amino acids include meats, poultry, fish, eggs, and dairy products.

Foods that hinder zinc absorption

• Phytate-rich foods: Phytates are compounds found in plant foods, such as whole grains, legumes, nuts, and seeds. Phytates can bind to zinc and prevent its absorption.
• Calcium-rich foods: Calcium can also bind to zinc and prevent its absorption. However, this is only a concern if you consume large amounts of calcium-rich foods at the same time as zinc-rich foods.
• Foods high in fiber: Fibre can bind to zinc and prevent its absorption. However, this is only a concern if you consume large amounts of fiber-rich foods at the same time as zinc-rich foods.

What is Zinc Bioavailability?

Zinc bioavailability, as opposed to absorption, is a measure of how much of the absorbed zinc is actually available for use by the body when it needs it. In other words, it is the proportion of zinc that is absorbed and transported to the tissues where it is needed.

Zinc bioavailability can be assessed through a variety of methods, including:

• Measuring the amount of zinc in the blood or urine after ingestion
• Observing the effects of zinc supplementation on zinc-related biomarkers, such as the immune response
• Using animal models to study the absorption and utilization of zinc

Organic forms of zinc, such as zinc picolinate and zinc citrate, tend to have higher bioavailability than inorganic forms, such as zinc oxide.

How to Absorb More Zinc: Best Practices 

Here are some strategies for maximizing zinc absorption:

• Choose a highly bioavailable form of zinc. Some forms of zinc are more bioavailable than others. 
• Take zinc with food. Taking zinc with food can help to improve its absorption. However, it is important to avoid foods that contain phytates, as these can interfere with zinc absorption.
• Avoid taking zinc with other minerals. Zinc can interact with other minerals, such as copper and calcium, and reduce their absorption.
• Take zinc in divided doses throughout the day. Taking zinc in divided doses throughout the day can help to improve its absorption.
• Avoid alcohol. Alcohol can interfere with zinc absorption.

By following these strategies, you can maximize the absorption of zinc and improve its health benefits.

Here are some additional things to consider when taking zinc supplements:

• The dosage: The recommended daily intake of zinc is 8 mg for adult men and 11 mg for adult women. However, some people may need more zinc, such as those who are pregnant or breastfeeding.
• The form of zinc: As mentioned above, some forms of zinc are more bioavailable than others. It is important to choose a form of zinc that your body can absorb well.
• The timing of intake: Zinc absorption can be affected by the presence of food and other nutrients. It is important to take zinc at a time when its absorption will not be hindered.
• The interactions with other medications: Zinc can interact with certain medications, such as antibiotics and diuretics. It is important to talk to your doctor before taking zinc supplements if you are taking any medications. 

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