It’s important to get vitamin C from food sources or supplements as your body cannot produce it. For most people, a cup of orange, broccoli, red pepper provide with enough vitamin C for a day. The daily recommended amount of vitamin C is 65 to 90 milligrams. The upper limit is 2,000 milligrams. Though dietary vitamin C does not cause any harmful effects but megadoses of vitamin C supplements can cause nausea, diarrhoea, headache, heartburn, vomiting, insomnia and cramps. While there are various foods that can help you meet the daily recommended intake, there is also a simple trick that you can try to up your levels of vitamin C.