Zinc

Zinc is a mineral that is essential for many of your body's normal functions and systems, including:

• your immune system and fighting off infection
• skin health and wound healing
• blood clotting
• thyroid function
• senses of taste and smell.

Zinc also supports normal growth and development during pregnancy, childhood, and adolescence.

Zinc is found in a wide range of foods including:

• oysters (best source of zinc)
• red meat, poultry, fish and seafood 
• beans, nuts, seeds, whole grains (eg, oats)
• dairy products.

By eating a wide range of food groups, it's rare to develop zinc deficiency.

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Recommended dietary intake

The amount of zinc you need each day depends on your age. The following is the recommended dietary intake (RDI) of zinc for people of different age groups.

• Babies (0 to 6 months): 2 mg (*AI)
• Babies (7 to 12 months): 3 mg
• Children (1 to 3 years): 3 mg
• Children (4 to 8 years): 4 mg
• Children (9 to 13 years): 6 mg
• Boys (14 to 18 years): 13 mg
• Girls (14 to 18 years): 7 mg
• Adult men (19+ years): 14 mg
• Adult women (19+ years): 8 mg
• Pregnant teens  (14 to 18 years): 10 mg
• Pregnant women  (19+ years): 11 mg
• Breastfeeding teens (14 to 18 years): 11 mg
• Breastfeeding people (19+ years): 12 mg
  
  

* Adequate intake (AI) is the recommended average daily intake of a nutrient which is used when there isn't enough information to determine the RDI. This is the case for young babies.

Testing

Zinc levels can be tested with a blood test, but it's not commonly done and is usually not necessary. It may be occasionally required when there is severe undernutrition or an underlying medical condition (eg, gastrointestinal disease or following gastrointestinal surgery).

Most people will get enough zinc by eating a healthy, balanced diet. Your healthcare provider may recommend a zinc supplement to treat zinc deficiency.

Always talk to your doctor or pharmacist before taking a supplement, as taking too much zinc can cause side effects and interfere with the absorption of other nutrients you need, eg, copper and iron.

People at higher risk

• People with gastrointestinal conditions (eg, ulcerative colitis, Crohn's disease or newly diagnosed coeliac disease) and following weight loss (bariatric) surgery:
  • these conditions decrease the amount of zinc your body absorbs and increase the amount lost in your urine.
• Vegetarians (especially vegans) or people on long-term restricted diets:
  • meat, chicken, fish and seafood is a good source of zinc
  • zinc is better absorbed from animal-based foods than plant-based foods
  • beans and grains often eaten by vegetarians contain a compound called phytate which reduces the absorption of zinc.
• Older infants who are exclusively breastfed (only have breast milk):
  • breast milk doesn't have enough zinc for infants over 6 months of age
  • they should be given foods that have zinc, eg, pureed meats
  • formula-fed infants get enough zinc from infant formula.
• People with high alcohol use or dependency
  • alcohol decreases the absorption of zinc in your gut and increases the amount of zinc excreted in urine.
• People with sickle cell disease may also need more zinc.
• Women who are pregnant or breastfeeding have slightly higher zinc requirements.

The section above describes the groups of people who may not be getting enough zinc. If you are in one of these groups, talk to your healthcare provider to see if you need to take a zinc supplement or multivitamin (which usually has zinc as an ingredient).

Zinc for the common cold?

It has been suggested that zinc may help speed recovery from the common cold and reduce its symptoms if it's taken within 24 hours of cold symptoms starting.

A recent review found that zinc may provide some limited benefits for people with the common cold, eg, reducing the length of symptoms by about 2 days. However, there's not enough high-quality evidence to recommend zinc supplementation for the prevention or treatment of the common cold.

Zinc for age-related macular degeneration (AMD)

Age-related macular degeneration (AMD) is an eye disease that gradually causes vision loss as you get older. It affects the central area (macula) of the back of your eye. 

Antioxidant vitamins and minerals may help to protect the macula and prevent loss of vision.

A recent review of studies found taking an antioxidant multivitamin supplement (containing vitamins E and C, beta‐carotene plus zinc) probably slows down the progression of AMD and vision loss. However, the studies in this review were small which means there is lack of good evidence around the safety of this approach. It's important to talk to your doctor about the safety of a supplement for you and your individual needs.

If you're thinking about taking a zinc supplement, talk to your healthcare provider first as it may interact with other medicines you're taking.

Taking too much zinc can lead to:

• nausea (feeling sick) and vomiting (being sick)
• diarrhoea (runny poo)
• abdominal (stomach) cramps
• headaches.

Zinc can be present in some denture adhesive creams

• Using large amounts of these products, well beyond recommended levels, could lead to excessive zinc intake and copper deficiency.
• This can cause neurological problems, including numbness and weakness in your arms and legs.