Beneficial effects from any particular diet have not been proven in multiple sclerosis (MS). Therefore, the general guidelines on nutrition should be followed. Obesity and various forms of malnutrition worsening the MS symptoms are frequently observed. There is some evidence from epidemiological studies that a high consumption of saturated animal fat is associated with an increased incidence of MS. The findings from such studies indicate that supplementation with unsaturated fatty acids, in particular omega-3 fatty acids, could positively influence the course of MS. However, controlled studies did not show clear beneficial effects from polyunsaturated fatty acids. The intake of vitamin D is associated with a lower incidence of MS. In contrast, the effects of therapy with vitamin D on the course of MS have not been ascertained. Patients with MS carry an enormous risk of osteoporosis, and therefore the indication for a preventive therapy with vitamin D and calcium should be established in every postmenopausal woman or after repeated steroid treatments.