Zinc (Zn) is something that has long been associated with Chemistry class and not a vital part of the diet, but in fact Zinc is essential for a multitude of health properties within the body. Zinc in its pure form is a mottled dark silver metal, on the other hand, in nutrition we see it abundantly in red meats and shellfish.
The History of Zinc…
History dictates that German Scientists Sigismund Marggraf discovered Zinc in its purest form in 1746. ‘Zinc’ comes from the German word ‘Zinke’ which roughly translates to Pronged tooth, thought to describe the mottled and mangled appearance of the pure metal. Despite its discovery in 1746 its use in history far precedes this. Realistically, since the beginning of time it has been used for its typically strong metallic structure in the production of tools, pots, and buckets. In its impure form it was mixed with other metals, such as lead, copper and iron to form stronger alloy metals.
The use of Zinc in health practices dates back to the Roman Era in which they attempted to treat ‘sore eyes’ with pills made from Zinc Carbonate. Also in 13AD, Sanskrit writing described the two kinds of Zinc, namely Calamine an oxide mix which was used for the treatment of ill skin, itching, sunburn and rashes. Whereas Smithsonite was a carbonate which they used for structural purposes . Zinc was made famous by explorer Marco Polo, that discovered Zinc was useful in reducing inflammation, and that Zinc Sulphate is a powerful antiseptic, ideas that are still used today .
What is Zinc in terms of diet?
Despite Zinc being found in almost all cells of the body it is still considered a trace mineral, which means in comparison to some other minerals it is required and found in much smaller amounts within the body. Approximately <0.1% of the body’s Zinc content is found in the blood, however this is a poor indicator of the nutritional status and deficiency . Zinc is viewed as important due to its roles in the immune system, DNA production and enzymatic reactions.
What foods is it found in?
The following foods contain dietary sources of Zinc:
- Shellfish, Oysters, Crab and Lobster.
- Nuts (Almonds and Cashews)
- Fortified Cereals
- Legumes (Haricot beans, Chickpeas, Kidney)
The richest sources of which are Shellfish and Beef, plant sources contain very small amounts of the trace mineral Zinc, thus more must be eaten to reach daily needs. Additionally, the Zinc found in meats and shellfish are the most bioavailable which means that it absorbs better than any plant variety. Moreover, plant sources are rich in phytates, which themselves have therapeutic health properties but prevent the absorption of Zinc, they are known as antinutrients .
How much do we require?
In our daily diets, we require differing amounts of Zinc dependent on our gender and where we are in our life cycle. The table show below demonstrates this:
|Gender||Age (years)||Zinc Requirement|
|Lactation (4months)||+6.0 (13.0)|
|Lactation (4-6 months)||+2.5 (9.5)|
Table 1: Specific Zinc Requirements 
Men require more Zinc because it is essential for their fertility. Zinc is found in abundance in the reproductive organs of a man. Considering that Spermatogenesis (production of sperm) occurs on a 70 day cycle it is of great importance that Zinc is consumed in regularly.
Lactating women require more Zinc because the infant requires more for growth, additionally the act of breastfeeding will deplete the mother’s Zinc stores as they are given to the infant through the milk.
Those most at risk of deficiency include Vegans and Vegetarians. Their diet contains very few rich sources of Zinc, so they must consume greater volumes to meet their daily requirements. Also, Vegetarian diets are based around legumes such as lentils and chickpeas. These types of foods are rich in phytates which are antinutrients to Zinc absorption. It’s thought that Vegans and Vegetarians may need to consume at least 50% more Zinc to absorb the correct amount into their body’s. The elderly, or any person who has a gastrointestinal disease or diarrhoea may also be at risk of deficiency, this is because it reduces their ability to absorb Zinc which can lead to more serious disease such as infertility, liver and kidney disease. Pregnant and lactating women are also at risk of deficiency as motherhood strips the body of its natural Zinc reserves to give to the infant. Nutrition at this portion of life is important for both child and Mother .
Zinc Deficiency Symptoms include:
- Weakened immune system and frequent opportunistic disease.
- Poor sense of smell or taste.
- Brittle and thinning hair, which can often lead to hair loss.
- Slow growth
- Slow wound healing
- Poor Appetite
- Kidney or liver disease.
What are its health properties?
Eye Health and Zinc
Even as far back as the Roman Era they knew that Zinc played an important role in eye health. Little did they know, but Zinc is a rich antioxidant that is responsible for preventing reactive free radicals from attacking the eye surface and reducing its capabilities. Zinc is particularly associated with the health of the Retina. As previously mentioned Zinc is an essential component of numerous enzymes, including those in the eyes. Superoxide dismutase is one, this is the primary enzyme in the fight against free radicals. It has been shown that Zinc deficiency increases susceptibility of oxidative damage to the eye . One study took 151 patients and administered high dose Zinc supplements. It was found that despite even small loses of vision in a small percentage of the Zinc group it was nothing compared to the loss of vision in the placebo group. This is evidence that Zinc has protective role in ageing of the eye and macular degeneration .
Boost to your immune system
As the symptoms of Zinc deficiency show, a reduction in biological status of Zinc leads to inhibited immune function. Zinc is involved in numerous enzymatic reactions that are required for adequate immune function and activation of the T and B lymphocytes used as part of the attack against invading pathogens. It’s thought that in 3rd world countries where overall nutritional status is poor, particularly in Zinc, there is an increased risk of serious infections such as Pneumonia.
It has long been thought that the common cold was helped only by Vitamin C, when contrary to common belief, science has proved that it is in fact Zinc which helps protect us. A study of 50 people taking Zinc lozenges found that compared to a placebo group the duration and severity of symptoms in their cold were signigicantly reduced .
Can it help with male fertility?
Males require high levels of dietary Zinc due to fertility needs. Zinc is thought to aid quality and quantity of sperm produced. One study took a group of males that consumed 10% of the daily requirement amount of Zinc, for a month. At the end of this month ‘composition’ and ‘quantity’ were measured. Those that consumed just 10% of the daily requirements had decreased quantity, quality and motility of sperm, in confirmation even small periods of Zinc deficiency can lead to reduced fertility.
In addition to the above ailments, Zinc has also been proven to help speed wound healing, sense of taste, sense of smell, cell integrity, and health of the skin, hair and nails [4,9]. For whatever reason, Zinc is sometimes hard to incorporate into the diet, whether it be dietary choice, reduced absorption or other. Supplementation is always advisable as you get a high dose of pure Zinc in its bioavailable form. You are recommended to take a dose between 5-45mg dependent on your dietary needs. We always recommend starting at the lower dose and slowly increasing to your needs. The largest dose isn’t always the most helpful to you .
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- Prasad AS, Beck FW, Bao B, Snell D, Fitzgerald JT. Duration and severity of symptoms and levels of plasma interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, and adhesion molecules in patients with common cold treated with zinc acetate. J Infect Dis 2008 ;197:795-802.
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