Blogs, podcasts, and social media accounts can all be valid sources for research. However, you have to be a discerning consumer of such sources, evaluate their credibility carefully, and be sure you know how to identify content marketing.
Blogs
The best blogs will be either the work of one or two individuals whose credentials you can verify or will be associated with another reliable media source, such as The New York Times, The Wall Street Journal, or the Associated Press. For most types of research, avoid blogs with corporate authors, which function as content marketing.
Podcasts
Good podcasts can be a place to find informative conversations among experts in a wide variety of fields. Look for podcasts where you can verify the credentials of the guests and the hosts. Some podcasts also claim they are fact checked, which would be another signal of reliability, if you can confirm it.
Like blogs, podcasts are also often associated with other credible sources of information--The New York Times puts out The Daily, for example, and The Wall Street Journal offers What's News.
Also like blogs, podcasts can serve as content marketing. For most research purposes, you would want to avoid podcasts affiliated with companies.
Social Media Accounts
Useful social media accounts, on a variety of platforms (LinkedIn, Twitter, Instagram, etc), provide a place for experts to offer insights. Look at their bio and verify credentials before citing an individual's account.
Following the account of another reliable source can also be a way to stay up to date on different types of news. For example, you might follow the Harvard Business Review on Twitter to stay current on topics they cover. You also might follow an individual journalist, if you know they cover your field regularly.
Avoid corporate social media accounts for research unless you are specifically interested in how a company is using social media or what that company is promoting.