Whole grains are an important part of a healthy diet, but other aspects of your lifestyle might not be letting them reach their full potential. Taking antibiotics can actually neutralize the healthy effect that whole grains have on the body, a new study shows.

As part of the MyPlate initiative, it is recommended that whole grains take up about one quarter of your plate at each meal. This comes to a daily total of between three and six ounces, depending on the activity levels and gender of the person. Whole grains are a rich source of lignans, which have been purported to decrease risk of cardiovascular disease, and possibly even reduce the risk of certain cancers (although the research is still a little bit contradictory on this subject).

Especially in women, lignans can have a more substantial effect. This is because lignans are absorbed into the body as estrogen, and can help to balance hormone levels. Similarly, the use of antibiotics in women is more likely to destroy the healthy benefits of lignans. In fact, women who took antibiotics within three months of being tested for lignan levels showed an average of 40 percent less than those who did not.

Antibiotics are meant to kill bad bacteria, but the good bacteria can be affected as well. That is where the breakdown of lignans occurs upon entering the body: in the gut bacteria. When antibiotics are introduced to the mix, the effect can be long-lasting and can effectively neutralize the health benefits that lignans can provide.

Over 2,200 people were tested for lignan levels using blood, tissue and urine samples. They also provided a detailed report of their health and lifestyle habits, including diet and use of medication. Antibiotics showed an almost direct link to lower lignan levels.

“You will not achieve the full beneficial effects of whole grain, when the intestinal bacteria are negatively affected by antibiotics. Most likely, it also applies to a number of other compounds present in the diet and which require microbial conversion in order to have a positive effect on health,” said Knud Erik Bach Knudsen. Knudsen is part of the Department of Animal Science at Aarhus University.

The takeaway? Only take antibiotics as prescribed. And of course, maintain a healthy lifestyle of healthy eating, exercise and proper supplements.

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