Are You Getting These Nutrients? - Part 14

Zinc is an essential trace mineral, so you get it through the foods you eat. Next to iron, zinc is the most common mineral in the body and is found in every cell. It has been used since ancient times to help heal wounds and plays an important role in the immune system, reproduction, growth, taste, vision, and smell, blood clotting, and proper insulin and thyroid function.

Zinc also has antioxidant properties, meaning it helps protect cells in the body from damage caused by free radicals. Free radicals may contribute to the aging process, as well as the development of a number of health problems, including heart disease and cancer. Antioxidants can neutralize free radicals and may reduce or even help prevent some of the damage they cause.

Your body doesn't need a large amount of zinc. The recommended daily allowance for adults is 8 - 11 mg. It’s common to have slightly low levels of zinc, but taking a multivitamin, plus eating a healthy diet, should give you all the zinc you need.

It's rare for people in industrialized countries to be seriously deficient in zinc. Low zinc levels are sometimes seen in the elderly, alcoholics, people with anorexia, and people on very restricted diets. People who have malabsorption syndromes, such as Crohn's disease or celiac disease, may also be deficient in zinc.

Symptoms of zinc deficiency include loss of appetite; poor growth; weight loss; lack of taste or smell; poor wound healing; skin problems such as acne, atopic dermatitis and psoriasis; hair loss; lack of menstrual period; night blindness; white spots on the fingernails; and depression.

Zinc reduces the amount of copper your body absorbs, and high doses of zinc can cause a copper deficiency. For that reason, many doctors recommend that you take 2 mg of copper along with a zinc supplement.

Your body absorbs 20 - 40% of the zinc present in food. Zinc from animal foods like red meat, fish, and poultry is more readily absorbed by the body than zinc from plant foods. Zinc is best absorbed when taken with a meal that contains protein.

The best sources of zinc are oysters (richest source), red meats, poultry, cheese (ricotta, Swiss, gouda), shrimp, crab, and other shellfish. Other good, though less easily absorbed, sources of zinc include legumes (especially lima beans, black-eyed peas, pinto beans, soybeans, peanuts), whole grains, miso, tofu, brewer's yeast, cooked greens, mushrooms, green beans, tahini, and pumpkin, and sunflower seeds.

Zinc is available in several forms. Zinc sulfate is the least expensive form, but it is the least easily absorbed and may cause stomach upset.

More easily absorbed forms of zinc are zinc picolinate, zinc citrate, zinc acetate, zinc glycerate, and zinc monomethionine. If zinc sulfate causes stomach irritation, you can try another form, such as zinc citrate.

The amount of elemental zinc is listed on the product label (usually 30 - 50 mg). To determine the amount to take in supplement form, remember that you get about 10 - 15 mg from food.

Zinc lozenges, used for treating colds, are available in most drug stores. There are also nasal sprays developed to reduce nasal and sinus congestion, although they may have some safety issues.

You should take zinc with water or juice. If zinc causes stomach upset, it can be taken with meals. Don't take zinc at the same time as iron or calcium supplements.

A strong relationship exists between zinc and copper. Too much of one can cause a deficiency in the other. If you take zinc, including zinc in a multivitamin, you should also take copper.

Daily intake of dietary zinc (according to the National Academy of Sciences) are listed below:

Adult

• Men 19 years and older: 11 mg (RDA)
• Women 19 years and older: 8 mg (RDA)
• Pregnant women 14 - 18 years: 12 mg (RDA)
• Pregnant women 19 years and older: 11 mg (RDA)
• Breastfeeding women 14 - 18 years: 13 mg (RDA)
• Breastfeeding women 19 years and older: 12 mg (RDA)

You should not take high doses of zinc for more than a few days unless your doctor tells you to. Talk to your doctor before taking more than 40 mg of zinc per day and take breaks from zinc supplementation. During those breaks, get zinc from a well-balanced diet.

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable doctor.

Research has shown that less than 40 mg a day is a safe amount to take over time, but researchers are not sure what happens if more is taken over a long period. Additional concerns have been raised about combining multivitamins and additional zinc supplements and an increased risk of dying from prostate cancer. Speak with a physician.

Taking 100 mg of zinc daily, or taking supplemental zinc for 10 years or longer, has been linked with a doubling of the risk developing prostate cancer in men.

Common side effects of zinc include stomach upset, nausea, vomiting, and a metallic taste in the mouth. High doses of zinc can cause dizziness, headache, drowsiness, increased sweating, loss of muscle coordination, alcohol intolerance, hallucinations, and anemia.

There are reports that a single dose of zinc as high as 10-30 grams can be lethal.

Very high doses of zinc may actually weaken immune function. High doses of zinc may also lower HDL ("good") cholesterol and raise LDL ("bad") cholesterol.

Some people who have used certain zinc nasal sprays to treat a cold have lost their sense of smell. Talk to your doctor before using a zinc nasal spray.

Doctors Often Not Knowledgeable about Zinc

When I went to the pharmacy for a prescription, I saw the pharmacist trying to make sense of a prescription. She reached for the telephone and I could see her dialing. She asked for the doctor and then she asked why the prescription. I don't know what was said from there, but I could see the pharmacist discussing this with the person on the phone.

When she was done, she came back to the person that the prescription was for and asked if she really needed it. The person said she was low and that the doctor had tested her and wrote the prescription. I could hear the pharmacist tell the person that the prescription was for too large a dosage of zinc. I had just read this article and the pharmacist could see me cringe.

When she had finished giving the person the prescription and accepting the copay, I was next. I asked the pharmacist if she had the internet on the computers. She said she did and I asked her to open Eureka Alert and when she said it was up, I asked her to type zinc in the search box. She did and said there were many selections. I asked her if they had a search by date at the bottom and when she said yes, I said to click on that. Next, I asked her what the top article was. It was this article and I had her open it and suggested that she read it.

The pharmacist said she did not need to as she was aware of the problem and it was described quite well. I said that is why you saw me cringe. I said that the person would probably be back with a copper deficiency as well as anemia. The pharmacist agreed and since I had my prescription, I said yet doctors insist on over prescribing trace minerals because they don't know better. The pharmacist would not say any more, so I left.

A small audit of clinical practice, published online in the Journal of Clinical Pathology says, too much zinc, taken in the form of dietary supplements, may disrupt copper uptake, leading to neurological problems and anemia. While this happened in Great Britain, my discussion above indicates many doctors here make the same mistakes.

Zinc is an essential trace element that is required in daily quantities of 5.5 to 9.5 mg for men and 4 to 7 mg for women. But zinc supplements are usually only available in formulations of 45 or 50 mg. The US recommended tolerable limit is 40 mg/day. While there is no evidence to suggest that taking zinc supplements in the short term is harmful, this may not be the case for longer-term use, say the researchers.

These findings by the researchers underline the lack of awareness of zinc induced copper deficiency,' who caution, 'zinc is an essential trace element, and so clinicians may consider it a safe nutrient rather than a drug carrying potential risk.

Zinc Can Assist in Preventing Diabetes Damage

Because of the toxic nature of zinc, please do not do any supplemental zinc intake without knowledge of a doctor and only on his advice. For information on zinc and health problems read this – a little more than half way down the page under the heading “Health Risks from Excessive Zinc”. The rest of the article is good also. Bookmark it and go back to it after you read the following.

This is an interesting study about zinc and does deserve some attention as the National Institutes of Health provided funding for the research. The University of Michigan did the research and the findings appear in the July 8 issue of the Journal of Molecular Biology.

The findings showed that Amylin can display two characteristics. In people that have normal levels of zinc and are otherwise healthy, amylin assists in blood glucose management. An analog of amylin, named Symlin is used with insulin to manage blood glucose levels in people with diabetes. In molecular language, zinc prevents amylin, which is also known as Islet Amyloid Polypeptide, from forming clumps which can lead to the formation of ribbon-like structures called fibrils.

This happens in an environment that is zinc-starved and the fibrils become linked to some human diseases, many of them in the area of dementia. The important part is that zinc binds to amylin, at a point near the middle of the amylin molecule, the amylin molecule kinks, which interferes with the formation of toxic clumps. In the current work, they show that the binding of zinc in the middle makes one end of the amylin molecule, called the N-terminus, become more orderly.

In addition, the researchers found that before amylin can begin forming fibrils, zinc must be rousted from its nesting place. This eviction is costly in energetic terms, and the sheer expense of it discourages fibril formation. And because a single zinc molecule can bind to several amylin molecules, it ties up the amylin in assemblages that, unlike certain other aggregations, are not intermediates in the pathway that leads to fibril formation.

However zinc, like amylin, has a dual nature. At conditions similar to those outside islet cells, where even a tiny amount of amylin aggregates in the blink of an eye, zinc inhibits fibril formation. But in conditions resembling the inside of the cell, the inhibitory effect begins to wane and other factors, like insulin, take on zinc's security guard duties.

Amylin has not one, but two binding sites for zinc. Zinc prefers to bind at the first site -- the one in the middle of the amylin molecule, where its binding discourages fibril formation. But when there's too much zinc around, all the binding sites in the middle positions are occupied and zinc must attach to amylin at the second site, which counteracts the effect of the first site. This may explain why decreased levels of insulin -- the backup security guard -- inside islet cells of diabetics result in islet cell death.

Also read this blog about natural sources of zinc.