Is 18 mg of Zinc Daily Too Much? Recommended Intake for Vitamins C and E

Q: Is 18 mg of Zinc Daily Too Much? Recommended Intake for Vitamins C and E

Hello, Mr. Xiao Shi： 1. The recommended daily zinc intake for adult males should be between 15 to 35 milligrams. Zinc deficiency can lead to growth retardation, affecting height and weight. It can also result in slow wound healing, hair loss or slow hair growth

Zinc dosage

If you are consuming health supplements and taking two different types that both contain zinc, resulting in a total intake of 18 mg of zinc per day, this amount is considered to be within the tolerable upper intake level for adults, which is 40 mg per day.
Therefore, you are not exceeding the limit.
For vitamin C, the recommended daily intake is 90 mg for men and 75 mg for women.
The tolerable upper intake level for vitamin C is 2,000 mg per day.

For vitamin E, the recommended dietary allowance is 15 mg for adults, and the tolerable upper intake level is 1,000 mg per day.

Exceeding these upper limits could lead to adverse effects, so it's important to monitor your total intake from all sources.

Xiao Shi, 20~29 year old female. Ask Date: 2019/02/17

Dr. Hou Fangmin reply Pharmacology

Hello, Mr.
Xiao Shi:
1.
The recommended daily zinc intake for adult males should be between 15 to 35 milligrams.
Zinc deficiency can lead to growth retardation, affecting height and weight.
It can also result in slow wound healing, hair loss or slow hair growth, and the appearance of white spots or poor growth and brittleness of nails.
While supplementation is possible, it can also have side effects.
It is best to obtain zinc from natural food sources, such as seafood—oysters are particularly rich in zinc—liver, whole grains, pumpkin seeds, chestnuts, eggs, dairy products, and sesame seeds.
2.
Vitamin C is a water-soluble vitamin, and the recommended daily intake for adults is between 100 milligrams to 2000 milligrams, with a maximum limit of 2000 mg.
At 100 mg, the absorption rate can reach 80–90%.
When the intake reaches 200 mg, the body’s absorption rate can reach saturation.
However, at an intake of 1500 mg, the absorption rate drops to 50%.
Therefore, there is no need for excessive intake of vitamin C.
The most common side effects of high-dose vitamin C are gastrointestinal discomfort, such as nausea, vomiting, abdominal cramps, and diarrhea.
It is advisable to obtain vitamin C primarily from food sources.
3.
Vitamin E is a fat-soluble vitamin and should not be taken in excess.
The optimal daily intake for health benefits is 200 IU, with an upper limit of 400 IU.
Excessive intake can lead to accumulation in the body, increasing the burden on organs and potentially producing toxins, which may induce heart disease.
Additionally, vitamin E can interact with anticoagulants, enhancing their effects, particularly in individuals taking anticoagulants, which may increase the risk of bleeding.
This should be approached with caution.
Do you understand the above information clearly? Wishing you a happy Lantern Festival!

Reply Date: 2019/02/17

More Info

When it comes to zinc intake, the recommended dietary allowance (RDA) for adult males is approximately 11 mg per day, while the upper intake level (UL) is set at 40 mg per day. Therefore, consuming 18 mg of zinc daily is within the safe limits for most adults, but it is important to consider the total intake from all sources, including dietary supplements and food. If you are taking two different supplements that together provide 18 mg of zinc, you should ensure that your total daily intake from food and supplements does not exceed the upper limit of 40 mg.
Zinc is an essential mineral that plays a crucial role in various bodily functions, including immune response, protein synthesis, wound healing, DNA synthesis, and cell division. However, excessive zinc intake can lead to toxicity, resulting in symptoms such as nausea, vomiting, loss of appetite, stomach cramps, diarrhea, and headaches. Long-term excessive intake can also interfere with the absorption of other essential minerals, such as copper and iron.

Regarding vitamins C and E, the recommended daily intake for vitamin C is generally around 90 mg for adult males, with an upper limit of 2,000 mg per day. Vitamin C is a water-soluble vitamin that acts as an antioxidant and is important for the growth and repair of tissues in the body. It is also necessary for the production of collagen, which is vital for skin, cartilage, tendons, ligaments, and blood vessels. While vitamin C is generally safe, high doses can lead to gastrointestinal discomfort, including diarrhea and nausea.

For vitamin E, the recommended dietary allowance for adult males is about 15 mg (or 22.4 IU) per day, with an upper limit set at 1,000 mg (or 1,500 IU) per day. Vitamin E is a fat-soluble antioxidant that helps protect cells from oxidative damage and supports immune function. However, excessive intake of vitamin E can increase the risk of bleeding, especially in individuals taking anticoagulant medications, as it can interfere with blood clotting.

In summary, an intake of 18 mg of zinc daily is not considered excessive for most adults, but it is essential to monitor total intake from all sources. For vitamins C and E, adhering to the recommended daily allowances and being aware of the upper limits can help prevent potential adverse effects from excessive supplementation. Always consult with a healthcare professional before making significant changes to your supplement regimen, especially if you are taking multiple products that may overlap in their nutrient content.

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