How do you know what to believe in the Internet?

Nutrition is a minefield and there is so much bollocks out there. Honestly the best thing you can do is just be aware of very simple rules and don't get too worried about specific issues. Basically eat a varied diet of different types of meat, fish etc, have plenty of veg, some fruit, and some starchy foods like pasta etc. 'Brown' varieties of bread pasta rice etc are better. Beans, lentils, etc all great. Keep fatty or sugary treats (incl sugary drinks) to a minimum (but no need to completely avoid) and don't drink too much alcohol. Ideally cook fresh when you can and minimise ready made or highly processed foods. Follow that even vaguely and you're eating more healthily than most of the country.