Acts as an electroneutral and low-affinity sodium (Na(+))-dependent sodium-coupled solute transporter. Catalyzes the transport across the plasma membrane of many monocarboxylates such as lactate, pyruvate, nicotinate, propionate, butyrate and beta-D-hydroxybutyrate. May be responsible for the first step of reabsorption of monocarboxylates from the lumen of the proximal tubule of the kidney and the small intestine. May play also a role in monocarboxylates transport in the retina (By similarity). Mediates electroneutral uptake of lactate, with a stoichiometry of 2 Na(+) for each lactate (By similarity). Cotransport of monocarboxylates and nicotinate strongly inhibited by ibuprofen, fenoprofen and ketoprofen. Detected at the brush border membrane of the kidney. Colocalizes with viementin in Mueller cells (By similarity). Belongs to the sodium:solute symporter (SSF) (TC 2.A.21) family.