There are several natural sources of lithium. Your lithium intake may depend on the foods you eat and the soil where these foods are grown. A study in the "Journal of the American College of Nutrition" states that lithium may be important for early fetal development, and for the proper functioning of enzymes, hormones and vitamins. This study states that a tentative RDA is set at 1,000 mcg per day for an adult who weighs 70 kilograms, or about 154 pounds. Lithium is also used as a medication to manage bipolar disorder. It decreases abnormal brain activity, according to Medline Plus.
Grains and Vegetables
Lithium is naturally present in many grains and vegetables. According to a study published in the "Journal of the American College of Nutrition," grains and vegetables may comprise 66 to 90 percent of a person's lithium intake. If you eat 0.85 kilograms of fruits and vegetables, the lithium level is 0.5 to 3.4 milligrams/kilograms. The study states that a diet rich in vegetables and grains may provide you with more lithium than a diet rich in animal products. However, the amount of lithium varies, depending on the amount in the soil where the plants grow.
Although the majority of lithium is found in plant sources, some lithium may also be obtained from animal food sources. The study in the "Journal of the American College of Nutrition" reports that a food intake of 0.44 kilograms of dairy foods per day has a lithium content of 0.50 milligrams/kilograms. Meat also contains lithium. If you eat 0.21 kilograms of meat per day, you'll get a lithium content of 0.012 milligrams/kilograms.
Soil and Water
Lithium occurs naturally in soil. From the soil, plants take up lithium, and when you consume plant foods you receive this lithium content. Lithium can also be obtained from water sources. The "Journal of the American College of Nutrition" states that 1 to 10 micrograms of lithium have been found in surface water, while 0.18 micrograms/Liter of lithium has been found in sea water.