The Effects of Taking Zinc on an Empty Stomach

If you have a zinc deficiency, or if zinc will help to treat a medical condition, you may consider taking a zinc supplement. Knowing the appropriate dosage, potential side effects and if you should take zinc with or without food will ensure you can take full advantage of the supplement.

Your body needs zinc for maintaining your immune system and supporting normal growth and development. Responsible for the chemical reactions of over 300 enzymes, zinc is necessary for protein synthesis, cell division, wound healing and hormone production. Zinc also functions as a neurotransmitter to help the cells in your body communicate.

Without zinc, you would have trouble smelling and tasting your food and the health of your eyes and skin could be impaired, according to National Institutes of Health (NIH).

Recommended daily allowances for zinc have been set by the Food and Nutrition Board, according to the NIH. These amounts are designated according to age and gender. Values are the estimated total requirements from food, water and supplements and are as follows:

• Children: 4 to 8 years of age — 5 milligrams; 9 to 13 years of age — 8 milligrams
• Males: 14 years and older — 11 milligrams
• Women: 14 to 18 years of age — 9 milligrams; 19 years and older — 8 milligrams
• Pregnant and lactating women: 11 to 13 milligrams

It's always best to get your nutrients naturally from the food in your diet. Because zinc is not stored in your body, you must get a daily supply to maintain adequate levels. The best source of zinc is oysters, which provide 327 percent of your daily value (DV) per six oysters. The top food sources of zinc include:

• Beef — chuck steak: 140 percent DV per 5-ounce steak
• Chicken leg — thigh and leg: 49 percent DV
• Tofu — firm: 36 percent DV per cup
• Lean pork chop: 32 percent DV per 6-ounce chop
• Hemp seeds: 26 percent DV per ounce
• Lentils: 23 percent DV per cup
• Low fat yogurt: 22 percent DV per cup

Many foods are fortified with zinc, such as ready-to-eat cereals and health bars. Grains can be a good source of zinc, but many contain phytates, which bind to zinc and reduce its absorption. Overall, animal foods are a better bioavailable source of zinc than plant-based foods.

If you are having a hard time getting an adequate supply of zinc from your diet, you may need to take a zinc supplement to treat a deficiency. Having a mild zinc deficiency is relatively common, especially for those who have certain conditions that might prevent proper absorption of the mineral. Some of these conditions can include:

• A restricted diet or being a vegan or vegetarian
• A digestive or malabsorption disorder, such as Crohn's, IBS or chronic diarrhea
• Chronic kidney or liver disease
• Alcohol abuse
• Diabetes
• Increased zinc loss from burns or prolonged diarrhea

If you have a risk factor for developing a zinc deficiency despite eating zinc-rich food, you might experience some of these symptoms of low zinc levels:

• Nausea
• Loss of appetite
• Growth retardation and development
• Weakened immune system
• Hair loss
• Slow wound healing
• Poor sense of taste and smell
• Delayed sexual maturation
• Rough dry skin and rashes
• Chronic and severe diarrhea

In addition to treating a deficiency, you might also consider taking a zinc supplement, or medication containing zinc, to prevent or treat a medical condition, such as a depressed immune function, macular degeneration or wound healing.

Zinc is a common ingredient in cold remedies such as throat lozenges and nasal sprays. Researchers have found that taking zinc at the onset of a cold may help reduce the duration of the illness. These findings were reported in a study with 1,387 participants and published in the ​Cochrane Database of Systematic Review ​in June 2013.

Zinc is also used to treat respiratory infections, such as pneumonia, and some diseases including malaria. Zinc is effective in treating acute diarrhea in children associated with high rates of mortality in developing countries.

Zinc plays a role in men's health. The sexual benefits of zinc include its potential to boost or maintain testosterone levels in men, according to a June 2014 study in ​Journal of Plant Biochemistry & Physiology​. Evidence also suggests that zinc may help protect men against the risk of prostate cancer, as published in ​Nature Review Urology​ in April 2013.

Zinc is available by prescription or over-the-counter in oral tablet, capsule, time-released, powdered, syrup, nasal spray and lozenge-type supplements. Zinc is often an ingredient in multivitamins or combined with other nutrients, such as copper, calcium or magnesium.

Always consult your doctor before taking a zinc supplement, as several forms are available, and each type may have differences in tolerability and bioavailability. Zinc supplements are made by combining various salts, so their percentage of elemental zinc varies. Some common forms are zinc gluconate, zinc sulfate and zinc acetate.

​Read more:​ Calcium Magnesium and Zinc Supplement Side Effects

Exceeding the USDA recommended tolerable upper intake level of 40 milligrams for adults may increase your risk of copper deficiency, advises the Linus Pauling Institute, and cause other side effects too.

For maximum effectiveness, it is advised that you take zinc on an empty stomach at least one hour before or two hours after meals. Whether you take zinc with or without food, do not take your zinc supplement at the same time as other vitamin pills.

A June 2013 study published in the journal ​Age​ showed that high concentrations of iron can have a negative effect on zinc absorption when zinc and iron are taken together on an empty stomach. Additionally zinc supplements taken at the same time as copper or phosphorus supplements may impede bioavailability. It is best to space doses of these products two hours apart.

If you eat certain foods with your zinc supplement, the zinc may not be absorbed and will not do your body any good. Avoid the following foods or eat them two hours after you take zinc.

• Bran
• Fiber-containing foods
• Phosphorus-containing foods such as milk or poultry
• Whole-grain breads and cereals

Although taking zinc before or after meals is the best way to get the benefits of the supplement, some people taking zinc on an empty stomach may experience gastrointestinal distress, such as nausea. The reason is that zinc supplements can release all the zinc salt in one location, causing irritation in many patients, as determined in a study published in the ​International Journal of Alzheimer's Disease​ in October 2013. The six-month trial found that a new zinc formulation in a slow-release form could be tolerated with no gastric intolerance with zinc on an empty stomach.

​Read more:​ 5 Harmful Side Effects of Getting Too Much Zinc

Along with its beneficial outcomes, zinc supplements may cause some side effects. If you experience any of these symptoms when you take zinc with or without food, check with your doctor.

In large doses, side effects may include:

• Chills
• Ulcers or sores in mouth or throat
• Fever
• Heartburn or indigestion
• Nausea
• Sore throat
• Tiredness or weakness

If you take an excessive amount of zinc over the recommended dosage, some more severe symptoms may be:

• Chest pain
• Dizziness
• Fainting
• Shortness of breath
• Vomiting
• Yellow eyes or skin