Frontiers in Nutrition is a reputable academic journal that covers a wide range of topics related to nutrition. It publishes research articles, reviews, and perspective papers that contribute to the advancement of knowledge in the field of nutrition. However, whether the journal can be considered a "warned" journal or not depends on multiple factors.

To determine if a journal is considered a warning or predatory journal, one must consider its editorial practices, reputation, indexing, impact factor, peer review system, and other relevant factors. These criteria can help distinguish trustworthy journals from those that are not, ensuring that researchers are submitting their work to reputable and trustworthy outlets.

Frontiers in Nutrition is published by Frontiers Media, a well-known and reputable publisher. The journal follows a rigorous peer-review process, where research articles are evaluated by experts in the field. This ensures the quality and credibility of the articles published in the journal. The transparent and rigorous peer review system is an important indicator that the journal is not a predatory one.

Furthermore, Frontiers in Nutrition is indexed in numerous reputable databases, including PubMed, Web of Science, Scopus, and others. Being indexed in these databases further validates the standing and reliability of the journal. Researchers often prefer to publish their work in journals that are indexed in well-known databases, as it enhances the visibility and reach of their research.

Another aspect to consider is the impact factor of the journal. The impact factor reflects the average number of citations received by articles published in the journal, indicating the influence and reach of the research. Frontiers in Nutrition has a respectable impact factor, indicating it is highly regarded within the scientific community.

In conclusion, based on the information above, Frontiers in Nutrition is not considered a predatory journal but a legitimate and reputable academic journal. It follows a stringent peer-review process, is indexed in reputable databases, and has a respectable impact factor. Researchers can confidently submit their work to Frontiers in Nutrition, knowing that their findings will be evaluated by experts in the field and reach a wide audience.