The immune system plays a vital role in protecting the body and ensuring good health. It is therefore of paramount importance to ensure that the immune system receives the necessary nutrition required for smooth functioning. One of the problems most individuals face is the inability to regulate intake so as to deliver the right amount of nutrients to the body. Ailments and impaired functioning of organs are attributed to the lack of adequate nutrition; this also occurs when there is excessive intake of nutrients. Let’s study the side effects of zinc and stay aware of the need to regulate intake in the right amount.


What functions or role does Zinc has in metabolism?


Zinc is not only essential it is present throughout the human body. Various actions and functions are attributed to zinc. This includes healing properties that help the body recoup from ailments or trauma. Imbalance in zinc results in loss of degradation of the sense of smell and the ability to taste food or liquids. Typically found in regular food products, such as chicken, and red meat, zinc is also present in sufficient quantities in cereals that are fortified. The body’s daily requirement of zinc will usually be met through intake of a balanced diet; however, the need for supplements arises when dietary intake is imbalanced. As a result of change in lifestyles, and diets, individuals end up consuming food that does not contain the required amount of nutrients. Consequently, there is a need to supplement the intake through readily available sources. The possibility of excessive intake occurs as a result of supplements, as individuals may end up consuming more than the required levels.


How much of zinc is safe to be consumed per day either through food or supplements?


Adhering to the safe limits either through dietary intake or through supplements will help to keep side effects of zinc out. There are clear cut recommended limits that can be easily followed. Here is the RDA, given below. It is necessary to add that the recommended amount is intended to serve as a reference value only. The actual requirement is likely to be different in certain instances, depending on various factors and health issues.


Children below 3 years : < 3 mg per day

Children between 4 and 8 : < 5 mg per day

Children between 9 and 13 : < 8 mg per day

Males above 14 : < 11 mg per day

Females above 14 : < 8 mg per day


The above RDA limits are average values for healthy individuals. There is an upper limit that should not be exceeded at any cost, as this may end up causing undesirable effects. To avoid toxic levels of zinc, it is necessary to ensure that it is below the safe upper limit as mentioned below :


Children below 3 years – maximum permissible limit – 7 mg per day

Children between 4 and 8 years – maximum permissible limit – 7 mg per day

Between 9 and 13 years – maximum permissible limit – 23 mg per day

Between 14 and 18 years – maximum permissible limit – 34 mg per day

Above 19 years – the maximum permissible limit – 40 mg per day.


Benefits of zinc in helping prevent or treat various conditions


While most individuals are unlikely to have known much about the importance of zinc, Covid-19 may have helped create awareness. All patients afflicted or diagnosed with Covid-19 are likely to have been prescribed zinc supplements. This is mainly an effort to boost the immune system to fight the symptoms associated with the condition. Prior to the outbreak of the virus, zinc was most likely to be known as supplements prescribed to treat common cold. Zinc has also been used traditionally in the treatment of wounds. Known for it shealing properties, zinc has always been recommended for wound management.


Another common condition that has been treated with zinc in some form has been mouth ulcers. Attributed to lower levels of zinc, skin ulcers can be effectively treated with zinc. Another common condition that has been effectively treated with zinc includes diarrhea. This is however restricted only to youngsters and may not be effective when used for treating diarrhea among adults. It is also important to add that zinc supplements used for treating diarrhea among youngsters are prescribed only when the condition has been diagnosed as a result of malnutrition with lower zinc levels in the body.


A common condition among adults, that is attributed to aging is macular degeneration. Seniors undergoing geriatric care are likely to be administered or recommended zinc supplements to fight back macular degeneration. The supplements help to delay the onset or the progression of the condition. Consequently, senior citizens benefit from improved vision. Zinc oxide either as cream or ointment is used for treating diaper rashes in individuals who use diapers due to various reasons.


Precaution to be followed when using zinc for treating common cold


While zinc supplements are known to be effective in treating common colds, there is the possibility of over use. A common action by many users is the urge to overuse or take excessive amounts of zinc, in an effort to fight certain conditions quickly. This may have adverse effects. Zinc supplements, when taken beyond the recommended limits may result in a loss of smell. Similar to anosmia, this condition can cause severe discomfort among individuals as the sudden loss of ability to smell, may be difficult to adjust.


What are the side effects of zinc that usually occur when on supplements?


As mentioned earlier, the possibility of adverse effects are unlikely due to regular dietary intake. This is because zinc that is naturally available in food products are not of levels that can result in excessive intake when food is consumed in large quantities. However, the possibility of excessive intake occurs when on supplements. Side effects of medications or supplements may not be common to all users. Some may experience adverse outcomes, while others may not experience any effect whatsoever. Similarly, the duration and intensity also differs from person to person. This depends on the overall health of the individual and specific conditions and medications in use.


The most common undesirable outcome of zinc is loss of smell, as listed above. The next commonly reported effect is vomiting as a result of the supplement. Other effects that are likely to be experienced are similar in nature, linked to vomiting. This includes nausea and possible headache. When higher amount of zinc is consumed, there is the likelihood of the individual ending up with indigestion and possible diarrhea. Another outcome of concern, is the possibility of zinc interacting or having an effect on other compound, such as copper. Reports indicate that zinc brings about a reduction in the levels of copper, which in turn may have undesirable outcomes. Neurological effects, numbing sensation and possible overall weakness are all manifestations of reduced levels of copper. It is therefore necessary to seek advice from a specialist about balancing or increasing the intake of copper to cope with the reduction as a result of zinc supplements.


Will zinc interact with other substances and is it a reason to be concerned?


Interactions are a possibility and cannot be ruled out altogether. Without exception, all medications, OTC products and formulations that are labelled as herbal or supplements are likely to interact with other products. This is because of the mechanism of actions that may be conflicting in nature, and could also be the result of the effect of ingredients on other ingredients. The outcomes of these interactions include a reduction in efficacy, or stronger outcomes beyond the desired or expected levels. Medications in prescribed strengths are recommended to achieve certain outcomes, and when interactions cause stronger outcomes, this could cause a negative effect.


Zinc is likely to cause a reduction in effectiveness of penicillamine, prescribed for rheumatoid arthritis. Patients on the medication who take zinc supplements may not receive relief from arthritis symptoms. It is however, possible to mitigate this interaction by staggering the time of intake of the medication and the time of intake of zinc supplements. Other interactions include thiazide diuretics, that may bring down the levels of zinc in the body. The diuretic has the effect of purging zinc through urination. Consequently, the desired outcomes of zinc supplements may not be experienced. Depending on the condition for which zinc supplements are consumed and the condition for which the diuretic is prescribed, it may be necessary to stop or stagger the timing of intake of either.


Certain categories of antibiotics, when taken along with zinc supplements may trigger undesirable interactions. The efficacy of the antibiotics may be impacted and it is therefore necessary to assess the importance of either medications/supplements and take suitable actions as recommended by the specialist. Tetracycline and quinolone are two of the antibiotics that may have lesser efficacy when taken with zinc supplements.


How to prevent or mitigate interactions with important medications?


While some interactions can be prevented easily by stopping zinc intake or medication intake, certain medications cannot be stopped. For instance, zinc also has an effect on ACE inhibitors that are medications known to have critical impact on health. In other words, patients cannot stop ACE inhibitors. Other important medications that cannot be stopped include hormone therapies, birth control pills, and proton pump inhibitors. In such situations it is necessary assess if zinc can be stopped till the treatment regimen involving the medications are stopped.


Interaction of zinc supplements with certain other medications or supplements can be handled or mitigated with a minimum interval of two hours. For instance, zinc is known to have an effect on antacids, iron and manganese. A gap of two hours between the intake of the above, will prevent undesirable outcomes.


Need to be cautious in calculating zinc intake


One of the reasons for excessive zinc intake is the possibility of other medications or supplements that contain zinc. Individuals are likely to consume zinc supplements separately, in addition to other medications or supplements that contain zinc. This combined intake may cause unwanted effects as a result of high levels of zinc in the body.


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