While following a lacto-ovo vegetarian diet may be more eco-conscious and sustainable than consuming meat, according to a 2010 United Nations Environment Programme report, it can also be low in certain vitamins and nutrients. (See Reference 1) The body processes certain minerals and vitamins differently when they come from meat sources than when they come from plant sources. In some cases, vitamins and nutrients are more common in animal products than in plant products, or are only found in animal products, meaning a vegetarian may need supplements.
Everybody needs vitamin B-12. This vitamin helps the body produce red blood cells; it is not found naturally in any plant-based foods, only foods that come from animal products. If you are a lacto-ovo vegetarian, you should be able to get adequate B-12 from eggs or dairy. If you do not consume much in dairy or eggs, you may wish to take a B-12 supplement. It is also often added to vegetarian foods such as soy milk or nutritional yeast. (See References 2 and 3)
Your body needs vitamin D to help the bones absorb calcium. It's often found in milk or added to non-dairy milks. Many people also absorb vitamin D through sunlight. In some climates, though, it can be difficult to get enough vitamin D from the sun in the winter. If you do not go outside during daylight hours, you also will not get your fair share of vitamin D and should consider a supplement. Look for supplements that contain D-2, which is a plant-based version of the vitamin. Vitamin D-3 is derived from the skin of animals. (See Reference 4)
Although not a vitamin, omega-3 is an essential nutrient for the body's health. It's a little trickier to get on a vegetarian diet, as one of the primary sources for it is fish. Vegetarian sources for omega-3 include flax seed, which can be ground up and added to cereal or smoothies, as well as walnuts and canola oil. You may decide to take an omega-3 supplement derived from algae to ensure you are getting enough in your diet. (See Reference 2)
Iron and Vitamin C
Your body does not absorb iron from plants such as kale as well as it absorbs iron from animal-based foods such as red meat. To deal with this, you should aim to consume twice as much iron as a non-vegetarian, according to the Mayo Clinic. (See Reference 3) Vitamin C, which is found in fruits such as berries and citrus, helps the body to absorb iron. When you eat iron-rich foods, such as beans and dark green vegetables, also eat a food high in vitamin C to improve absorption. For example, try a kale salad with slices of orange on it. (See References 2 and 3)
Based in Pennsylvania, A. Elizabeth Freeman has been writing professionally since 2007, when she started writing theater reviews for OffOffOnline.com and Theater Talk's New Theater Corps blog. Since then, she has written for Phillyist, TheNest, ModernMom and "Rhode Island Home and Design" magazine, among others. Freeman has an M.F.A. in dramaturgy/theater criticism from CUNY/Brooklyn College.