Give & Take

Give & Take

If you’ve got an age-related vision problem, there’s a good chance that your supplement regimen contains some zinc. If that’s the case, it’s time to talk to your doctor or a trusted health care practitioner who’s familiar with your medical history.

A new study shows that high levels of zinc may play a role in urinary problems.

Bright eyes

Zinc is one of the key nutrients needed for DNA reproduction and repair. Other health benefits linked to zinc intake include immune system enhancement, assistance in the repair of damaged tissues, and inhibition of abnormal blood clotting.

In addition, a daily zinc intake of 80 mg has been shown to help improve vision, while also reducing the risk of age-related macular degeneration (AMD).

In the e-Alert “Oyster Goggles” (10/11/04), I told you about the clinical trial known as the Age-Related Eye Disease Study (AREDS) sponsored by the National Eye Institute. For more than eight years, researchers tracked nearly 3,600 participants between the ages of 55 and 80 to examine the effects that antioxidant supplements have on AMD.

The results: High levels of zinc and antioxidants significantly reduced the risk of AMD. When the same supplements are administered in the early stages of AMD, vision loss that would normally be caused by advanced AMD may be inhibited.

The AREDS team recommended that anyone at high risk of developing AMD should consider taking daily supplements in the amounts used in the study:

Zinc (as zinc oxide) – 80 mg
Vitamin C – 500 mg
Vitamin E – 400 IU
Beta-carotene – 15 mg

Second opinion

As always, you should talk to your doctor before adding new supplements to your daily regimen – especially when using higher doses. And in the case of the AREDS recommendations above, zinc may need to be singled out for special consideration, according to a new study from researchers at the University of Wisconsin.

STUDY PROFILE The UW team gathered data from the AREDS study on more than 3,600 subjects with AMD

Each of the subjects received one of four intervention protocols: 1) Antioxidants in the amounts listed above, 2) Antioxidants plus 80 mg of zinc, 3) Zinc only, or 4) placebo

Data covered a six-year intervention period

Results showed that subjects who took the high dosage of zinc – either alone or with antioxidants – were more likely to be hospitalized for urinary tract infection, urinary retention linked to benign prostatic hyperplasia, and other urinary problems

These problems were more pronounced in men than in women

Women in the zinc group were more likely to develop urinary tract infections compared to women in the placebo group

As a side note, the study also showed no reduced risk for any type of cancer among those who took zinc supplements. But in their write-up in the Journal of Urology, the authors state: “A significant decrease in prostate cancer diagnoses was seen in patients receiving antioxidants vs placebo.”

Talk to your doctor

Further studies are needed to clearly establish a link between urinary problems and high zinc intake. Until such studies are completed, those who are taking zinc supplements to address AMD and other vision concerns should share this information with their doctors – especially if there’s a personal or family history of urinary complications.

Keep in mind that the UW results are associated with high doses of zinc. In other words, cutting out zinc altogether may not be the best answer. As HSI Panelist Allan Spreen, M.D., pointed out in a previous e-Alert, prostate enlargement is sometimes due to a deficiency of zinc and other nutrients such as omega-3 fatty acids.

Dr. Spreen also notes that regular zinc intake can create a copper deficiency, but just 1-2 mg of copper daily (an amount commonly included in multivitamins) will take care of that problem.

Good food sources of zinc include oysters, red meat, poultry, beans, nuts, whole grains and dairy products.