Read Original Release

What can zinc supplementation in 18 healthy US men reveal about global zinc needs? Not much.

Zinc eaten at levels found in biofortified crops reduces 'wear and tear' on DNA

Our Review Summary

This news release describes a new study looking at the correlation between zinc intake and DNA damage and consequently makes a case for biofortified crops like zinc rice and zinc wheat. Although the release does an exemplary job explaining the role zinc plays in our bodies, it doesn’t quite explain how this brief, small trial of 18 healthy men demonstrates the impact of zinc on cellular health. It uses vague, broad language to describe the study’s findings and dedicates only one sentence to detail the study design.

Part news release, part policy article and part biofortification promotion, the release argues for the need for food-based interventions, like crop biofortification, to address malnutrition and mineral deficiency around the world based on a small study of 18 healthy American men. That may be due to the fact that the research was funded by HarvestPlus, a research program advocating for biofortification to breed higher levels of micronutrients directly into staple food crops. We wish this funding source was disclosed in the news release, as well as the question of how prevalent the practice of biofortification already is around the world.

 

Why This Matters

Most US news releases relate studies like this one to dietary supplements, but this news release addresses hidden hunger and malnutrition. Zinc deficiency is a public health issue in many developing countries, especially those with rice-based diets. Access to seafood, red meat and poultry (foods rich in zinc) is also a challenge for many vulnerable populations. If crop biofortification is proven to be a safe, reliable and cost-effective way to deliver essential vitamins and minerals to nutrient-deficient populations, then it should be seen as a much needed food-based intervention to improve global health.

Criteria

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

Although zinc can be found in everyday foods such as oysters and red meat, the mineral can also be taken as a dietary supplement. A bottle of 100 zinc tablets goes for about $4 to $6 at the local drug store.

Since there is no discussion of costs in this news release, we give it a Not Satisfactory rating here.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

There is absolutely no discussion of any benefit data in the news release. Only vague, sweeping language is used to describe the effect of increased zinc intake. For example, the release states that the addition of 4 milligrams of extra zinc a day “can have a profound, positive impact on cellular health that helps fight infections and diseases” and “reduce oxidative stress and damage to DNA.”

In addition, the news release does not describe how the benefit was measured. It only mentions that scientists “used the parameter of DNA damage to examine the influence of zinc on healthy living.” How did scientists exactly count DNA strand breaks?

We would have liked to have seen some numbers here, which is why we give the news release a Not Satisfactory rating.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

We wish the news release mentioned that too much zinc is also harmful. According to the National Institutes of Health, increased zinc intake could lead to nausea, vomiting, loss of appetite, stomach cramps, diarrhea and headaches. When people take too much zinc for a long time, they sometimes have problems such as low copper levels, lower immunity and low levels of HDL cholesterol — sometimes referred to as the “good” cholesterol.

While this study was about food fortified with zinc, the news release was vague about how people should acquire their zinc, and this confusion could encourage people to reach for a bottle of zinc supplements.

For this reason, we give the news release a Not Satisfactory rating.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

Only one sentence was dedicated to the study design. We only know from the news release that the six-week study was randomized and controlled, as “scientists measured the impact of zinc on human metabolism.” We aren’t told how many people participated in the trial, how they took the zinc (through meals or supplementation), how much zinc was given and whether the study was blinded.

According to the original journal article, it turns out only 18 men took part in the trial. There was no control group per se, but participants were put on a controlled diet, in which zinc was depleted for two weeks and then repleted for the next four weeks. The study was not blinded.

We feel the news release should have pointed out that all of these factors introduce potential for bias into the trial.

Here’s one more point: Reducing DNA damage does not necessarily translate into better health outcomes, like increased life expectancy or lower rates of cardiovascular disease. Our bodies normally have mechanisms to repair DNA damage, which happens on a daily basis. And how are scientists so confident that zinc was specifically responsible for these lower numbers of DNA strand breaks?

We would have liked to have seen more discussion on the study design and limitations, which is why we give the news release a Not Satisfactory rating here.

Does the news release commit disease-mongering?

Satisfactory

There is no explicit disease mongering in this news release. However, the reference to “excessive DNA damage” from insufficient zinc consumption and the statement that “Zinc also helps limit inflammation and oxidative stress in our body, which are associated with the onset of chronic cardiovascular diseases and cancers” could plant fear in some readers’ minds.

Does the news release identify funding sources & disclose conflicts of interest?

Not Satisfactory

None of the authors reported conflicts of interest related to the study. The research was supported by a grant from HarvestPlus, a research program advocating for biofortification to breed higher levels of micronutrients — like iron, zinc and vitamin A — directly into staple food crops. Additional funding came from the NIH Office of Dietary Supplements.

The news release does not disclose these funding sources, which is why we give it a Not Satisfactory rating here.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

The alternatives here are to eat more natural foods rich in zinc or to take dietary supplements. Some sources of zinc include oysters, red meat, poultry, beans, nuts, whole grains and breakfast cereals.

Supplements contain several forms of zinc, including zinc gluconate, zinc sulfate and zinc acetate. According to the National Institutes of Health, research has not established whether differences exist among forms of zinc in absorption, bioavailability or tolerability. As we mentioned in the Costs section, a bottle of 100 zinc tablets is priced around $4 to $6.

Since these alternatives are not discussed, we give the news release a Not Satisfactory rating.

Does the news release establish the availability of the treatment/test/product/procedure?

Not Satisfactory

We wish the news release could have talked more about existing zinc fortification efforts around the world, since it’s not clear in the release whether zinc fortification practices are already in place.

In the original journal article, researchers mention the zinc fortification programs initiated in more than 30 countries and point out how Bangladesh increased its rice zinc concentration by 50 percent through its biofortification methods.

For this reason, we give the news release a Not Satisfactory rating.

Does the news release establish the true novelty of the approach?

Satisfactory

The news release states that this research is the first to show how modest increases in dietary zinc reduces oxidative stress and damage to DNA.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Satisfactory

The news release does not include unjustifiable, sensational language.

Total Score: 3 of 10 Satisfactory

Comments

We Welcome Comments. But please note: We will delete comments left by anyone who doesn’t leave an actual first and last name and an actual email address.

We will delete comments that include personal attacks, unfounded allegations, unverified facts, product pitches, or profanity. We will also end any thread of repetitive comments. Comments should primarily discuss the quality (or lack thereof) in journalism or other media messages about health and medicine. This is not intended to be a forum for definitive discussions about medicine or science. Nor is it a forum to share your personal story about a disease or treatment -- your comment must relate to media messages about health care. If your comment doesn't adhere to these policies, we won't post it. Questions? Please see more on our comments policy.