Tofu Consumption: Effects on Plasma Lipids in Rats

Abstract

SamplesOur objective was to determine the effect of a diet rich in tofu (soybean curd) on the main blood components of rats. This was done in comparison to diets with casein, soybean proteins or soybean oil, enabling the observed biological effect to be related to the composition of the tofu. Animals on the tofu diet had very low cholesterol levels and an acceptable HDL cholesterol / total cholesterol ratio. Growth and amino acid profile were also adequate, but the bioavailability of trace elements decreased.At the end of the experiment, blood was drawn from animals fasted overnight, by intracardiac puncture after anesthesia (intraperitoneal injection of nembutal, 50 mg/kg). Two types of samples were required. The first was placed in a dry tube for determination of blood glucose, the lipid components, the electrolyte balance, amino acids and iron. The second was over zinc-free heparin (Prolabo) for assays of trace elements (zinc and copper). In order to prevent chronobiological changes, samples were drawn at the same time in the morning.

Hypolipidaemic effects of dietary whole soybean curd (jeondubu) in rats

“…There is much evidence showing the hypolipidaemic action of soybean and its products, including soybean curd 4, 6, 7, 13–15, 28, 29. The present results showed superior lipid‐lowering effects of whole soybean curd in terms of serum lipid profiles compared with those of usual soybean curd.…”

“…The resulting insoluble soybean residue, consisting of hulls, fibre and other insoluble components, is either discarded or used in other foods after fermentation processing or in animal feeds. Many efforts have been made not only to increase the yield of tofu in processing but also to elucidate the biological effects of the product 12–15. Previously, we observed in rats that soybean curd residue exerted a cholesterol‐lowering effect in serum even when casein was supplied as dietary protein source 13.…”

“…Previously, we observed in rats that soybean curd residue exerted a cholesterol‐lowering effect in serum even when casein was supplied as dietary protein source 13. Furthermore, Roussel et al 14 showed in rats that tofu (soybean curd) as protein source exerted greater hypocholesterolaemic action than soy protein without affecting the concentration of triglycerides. Ashton and Ball15 reported a mild cholesterol‐lowering effect of tofu compared with lean meat in healthy male subjects.…”

“…Recently, a new process using whole soybean has been adopted for making soybean curd in Korea, and the new product, called Jeondubu (whole soybean curd), is widely sold in markets. Nevertheless, the beneficial effects of whole soybean curd produced by this new method have not yet been elucidated, though the cholesterol‐lowering action of usual soybean curd has been reported 14–18…”

Soya and cardiovascular prevention

“…De nombreux travaux ont montré chez l'animal la réduction du cholestérol lors de la substitution de la caséine par des protéines de soja [32] ou par du tofu [28]. Chez l'homme, cet effet existe aussi [23].…”