In one report, supplementation with essential fatty acids in the form of safflower oil (3–5 grams per day) reversed symptoms of lithium toxicity such as tremor and ataxia (an abnormality of gait).¹ Controlled studies are needed to confirm the benefit of a lithium-essential fatty acid combination.

Some studies have found that people taking lithium long term who have high blood levels of folic acid respond better to lithium.^{2 , 3} Not all studies have confirmed these findings, however.⁴

A double-blind study was conducted combining 200 mcg folic acid per day with lithium therapy.⁵ Even though the volunteers in this study were doing well on lithium alone before the study, addition of folic acid further improved their condition, whereas placebo did not. There is no evidence that folic acid reduces side effects of lithium. Based on the available evidence, it is suggested people taking lithium also take at least 200 mcg of folic acid per day.

A small double-blind study found that combining 2–4 grams three times per day of L-tryptophan with lithium significantly improved symptoms in people with bipolar disorder or a mild form of schizophrenia.⁶ L-tryptophan is only available from doctors. It should be taken several hours before or after meals.

Mild hand tremor is a common side effect of lithium therapy. Two cases of women treated with lithium who experienced increased tremor when they stopped drinking coffee have been reported.⁷ Lithium levels increased almost 50% in one of the women, who had been drinking 17 cups of coffee per day, requiring a 20% reduction in her lithium dose. In 11 people treated with lithium who drank four to six cups of coffee per day, two weeks without coffee resulted in increased lithium blood levels, anxiety , and depression.⁸ Lithium levels, anxiety, and depression ratings returned to base line two weeks after resuming coffee consumption. Until more is known, people taking lithium should avoid abrupt changes in their coffee consumption.

Lithium therapy has been shown to deplete brain stores of inositol.⁹ While it has been suggested that inositol supplementation (e.g., 500 mg three times daily) could reduce adverse effects of lithium therapy without reducing the drug’s therapeutic effectiveness,^{10 , 11} the safety and efficacy of this combination has not been proven.

Treatment with lithium can trigger or worsen psoriasis . In a double-blind study, supplementing with inositol (6 grams per day) for ten weeks significantly improved lithium-induced psoriasis, but had no effect on psoriasis in people who were not taking lithium.¹²

Addition of psyllium (Plantago ovata) husk two times per day to the regimen of a woman treated with lithium was associated with decreased lithium blood levels and lithium levels increased after psyllium was stopped.¹³

Lithium may cause sodium depletion, especially during initial therapy until consistent blood levels are achieved.¹⁴ A low-sodium (salt-restricted) diet can decrease lithium elimination, leading to increased lithium levels and risk of toxicity in lithium users who reduce their salt intake.¹⁵ Changing to a higher salt intake may cause increased losses of lithium, resulting in the return of mood symptoms.^{16 , 17} People using lithium therapy should maintain adequate water intake as well as a normal diet and salt intake. Sodium loss due to diarrhea , illness, extreme sweating, or other causes may alter lithium levels.

Foods that alkalinize the urine may increase elimination of lithium from the body, potentially decreasing the actions of the drug.¹⁸ Urine-alkalinizing foods include dairy products, nuts, fruits, vegetables (except corn and lentils), and others.