When first switching to a vegan/vegetarian diet, it can be difficult to know which foods to eat to get enough vitamins and nutrients in your diet. It definitely is possible when you eat a lot of fruits and vegetables, but it also helps to be knowledgeable about what to look out for. Here are some signs that you aren't getting enough of certain vitamins in your diet and what to do about it!
B12: B12 is important for your body because it is necessary to make red blood cells which carry oxygen throughout your body. If you don't have enough B12 then you can become anemic which means that your body does not have enough blood cells. Some symtoms of not having enough B12 are fatigue and weakness. Most people get B12 from meat, eggs, milk, seafood, and cheese which is why you are at risk for not getting enough when you switch to a vegan diet. There are also fortified foods, such as cereals, that contain B12. Seaweeds and nutritional yeast also contain B12. Personally, I take a B12 supplement (a multivitamin works, too), but eating foods fortified with B12 could be even better for you (if you can eat enough). For more info check out http://www.webmd.com/a-to-z-guides/vitamin-b12-deficiency-anemia-topic-overview
Iron: Iron is important for your body because it is important for your blood cells-those are pretty important! Symptoms of iron deficiency include fatigue, weakness, dizziness, headaches, brittle nails, and cold hands and feet. As always, bring concerns of deficiencies to your doctor. Iron can be found in meat, seafood, and eggs but it is also in spinach (calorie for calorie spincach has more iron than a steak), sweet potatoes, peas, kale, broccoli, lentils, bran and wheat products, iron fortified cereals, strawberries, watermelon, and raisins! A supplement can also be taken for iron (best if taken with vitamin C or orange juice/other food rich in vitamin C to help with absorption), but as you can tell it isn't too hard to get iron from natural sources which is best for your body.
Calcium: Calcium is important for your bones which are a pretty big deal. :) If you experince muscle cramping, increased PMS symptoms (for females), dry skin, or brittle nails, you may not be getting enough calcium in your diet. Calcium rich foods include milk, cheese, and yogurt but it can also be found in broccoli, green beans, kale, red kidney beans, almonds, sesame eeds, tahini paste, soy/rice milk, figs, and tofu. There are plenty of sources of non-dairy calcium that vegans can rely on for this important nutrient! Just a note, if you are a smoker your absorption and retention rates for calcium will be lower.
Protein: I'm sure that if you're a vegan, you know by now that it is a complete myth that you need animal products to get enough protien in your diet. Protien is in almost everything! Nuts, beans, legumes, tofu, nut butters, bulgar, soy products, quinoa, tempeh, the list goes on. Although most Americans get way too much protein in their diet, I often get the question of how I get enough protein. Don't believe this myth!
These are the big four that all vegans/vegetarians should be aware of, but there are others as well. Like I said, talk to your doctor if you have any concerns or questions (I am no where near as qualified as a doctor!) Also, here is another good source if you want to know more: http://www.veghealthguide.com/vitamins-minerals/