The truth is the best way to absorb these nutrients is through food. But without animal protein as an option, supplements are a good second best.
Make sure you read the labels on new supplements before you begin your regimen. Ask a nutritionist how much you should be taking for your age/weight/gender so you don't cause your body an unnecessary distress. Remember, you're making this switch to improve your health, there's no need for any setbacks due to lack of information.