Previous studies have demonstrated that milk fermented by specific Lactococcus lactis strains significantly inhibits the activity of angiotensin I-converting enzyme (ACE). However, the relationship between the ACE inhibitor and its in vivo action has revealed discrepancies. Therefore, the aim of the present study was to investigate the antihypertensive and heart rate (HR)-lowering effect of milk fermented by specific L. lactis in a murine model. Spontaneously hypertensive male rats (271 (SD14) g) were randomised into four treatment groups that were orally administered with milk fermented by L. lactis NRRL B-50 571 or L. lactis NRRL B-50 572 at 35 or 50 mg protein/kg body weight (BW), respectively. Further, two more groups were fed with different solutions as controls: a saline solution as the negative control and Captopril™ (40 mg/kg BW), a proven ACE inhibitor, as the positive control. Blood pressure and HR were monitored by the tail-cuff method before the treatments and at 2, 4, 6 and 24 h post-oral administration. The results demonstrated that milk fermented by L. lactis NRRL B-50 571 as well as by L. lactis NRRL B-50 572 presented an important systolic and diastolic blood pressure- and HR-lowering effect. Thus, milk fermented by specific L. lactis strains may present potential benefits in the prevention and treatment of CVD associated with hypertension in humans.

Hypertension or high blood pressure is a significant health problem worldwide. Typically, lifestyle changes, including adopting a healthy diet, are recommended for people with an elevated blood pressure. Lactotripeptides are bioactive milk peptides with potential antihypertensive properties in man. These peptides, as part of a food product or as nutraceutical, may contribute to the prevention and treatment of hypertension. This paper reviews the current evidence of the blood pressure control properties of lactotripeptides in man. Blood pressure-lowering effects of lactotripeptides are typically measured after 4–6 weeks of treatment. However, in some cases, a blood pressure response has been observed after 1–2 weeks. Maximum blood pressure reductions approximate 13 mmHg (systolic blood pressure) and 8 mmHg (diastolic blood pressure) after active treatment compared with placebo, and are likely reached after 8–12 weeks of treatment. Effective dosages of lactotripeptides range from 3·07 to 52·5 mg/d. Evidence indicates that lactotripeptides are only effective at elevated blood pressure; no further lowering of normal blood pressure has been observed. Concomitant intake of antihypertensive medication does not seem to influence the potency of lactotripeptides to lower blood pressure. Similarly, ethnicity has not been found to influence the extent of lactotripeptide-induced blood pressure lowering. Based on the currently available data, lactotripeptides appear to be safe and effective. Thus, they can be part of a healthy diet and lifestyle to prevent or reduce high blood pressure.