What foods are best to eat to gain calcium and nutrition?

I have this problem too and learned that I was becoming lactose intolerant, but if you aren't then dairy is a good idea. Leafy greens like bok choy, kale and seaweed are excellent calcium sources, and this may sound gross, but you can eat salmon with the bones in and get calcium that way too. It's also important to get enough Vitamin D and magnesium because these three work together. Vitamin D is high in fish, and especially in fish skins. It's also added to milk usually, so check your label. You can also spend at least 10 minutes outside in the sun each day, being sure to expose as much skin as possible to the sun's rays, and get Vitamin D that way. This will improve your mood too! Magnesium is generally pretty high in nuts and whole grains so you can get it from trail mix or granola. You can also take vitamin supplements but they aren't as effective because your body only absorbs a fraction of it. Your body can only take in limited amounts of vitamins at a time, so it's important to have multiple sources of these vitamins in your diet instead of trying to take it in one pill all at once.