Delay of stroke onset by milk proteins in stroke-prone spontaneously hypertensive rats

Milk Fermented with Mushrooms Prevents Stroke in the Stroke-Prone Spontaneously Hypertensive Rats Independently of Blood Pressure

OBJECTIVES

In a previous study, a mushroom was shown to digest milk protein to a mixture of oligopeptides and free amino acids. The aim of this study was to examine effects of this mixture, i.e., mushroom-fermented milk, on blood pressure and stroke susceptibility in the stroke-prone spontaneously hypertensive rats (SHRSP).

MATERIALS AND METHODS

Rats were fed mushroom-fermented milk with or without 1 % salt water. Blood pressure was monitored either by the tail-cuff method or the telemetry system. Symptoms of stroke were examined every day to determine the stroke latency.

RESULTS

Mushroom-fermented milk at 120 mg/Kg BW/day (estimated as a peptides/amino acids content) did not ameliorate hypertension in SHRSP. In contrast, mushroom-fermented milk significantly improved stroke susceptibility under salt-loading. The effects were replicated using milk fermented with three different mushrooms. To elucidate the effective components in mushroom-fermented milk, spermidine (3 mM), one of major components of mushroom-fermented milk, and a mixture of amino acids (0.8 g/L) was examined, both of which showed no significant effects on stroke susceptibility. Intake of mushroom-fermented milk did not affect sodium content significantly either in feces or in urine of the rats given 1% salt water. This observation indicated sodium absorption by the digestive system was not inhibited by intake of mushroom-fermented milk.

CONCLUSION

Despite that the mechanisms were not elucidated, intake of mushroom-fermented milk effectively prevented stroke in SHRSP. Mushroom-fermented milk would be a new candidate for a supplemental nutrient supporting the cardiovascular health.

A Review on Lactoferrin and Central Nervous System Diseases

Central nervous system (CNS) diseases are currently one of the major health issues around the world. Most CNS disorders are characterized by high oxidative stress levels and intense inflammatory responses in affected tissues. Lactoferrin (Lf), a multifunctional iron-binding glycoprotein, plays a significant role in anti-inflammatory, antibacterial, antiviral, reactive oxygen species (ROS) modulator, antitumor immunity, and anti-apoptotic processes. Previous studies have shown that Lf is abnormally expressed in a variety of neurological diseases, especially neurodegenerative diseases. Recently, the promotion of neurodevelopment and neuroprotection by Lf has attracted widespread attention, and Lf could be exploited both as an active therapeutic agent and drug nanocarrier. However, our understanding of the roles of Lf proteins in the initiation or progression of CNS diseases is limited, especially the roles of Lf in regulating neurogenesis. This review highlights recent advances in the understanding of the major pharmacological effects of Lf in CNS diseases, including neurodegenerative diseases, cerebrovascular disease, developmental delays in children, and brain tumors.

Milk Intake and Stroke Mortality in the Japan Collaborative Cohort Study-A Bayesian Survival Analysis

The aim of this study was to further examine the relationship between milk intake and stroke mortality among the Japanese population. We used data from the Japan Collaborative Cohort (JACC) Study (total number of participants = 110,585, age range: 40–79) to estimate the posterior acceleration factors (AF) as well as the hazard ratios (HR) comparing individuals with different milk intake frequencies against those who never consumed milk at the study baseline. These estimations were computed through a series of Bayesian survival models that employed a Markov Chain Monte Carlo simulation process. In total, 100,000 posterior samples were generated separately through four independent chains after model convergency was confirmed. Posterior probabilites that daily milk consumers had lower hazard or delayed mortality from strokes compared to non-consumers was 99.0% and 78.0% for men and women, respectively. Accordingly, the estimated posterior means of AF and HR for daily milk consumers were 0.88 (95% Credible Interval, CrI: 0.81, 0.96) and 0.80 (95% CrI: 0.69, 0.93) for men and 0.97 (95% CrI: 0.88, 1.10) and 0.95 (95% CrI: 0.80, 1.17) for women. In conclusion, data from the JACC study provided strong evidence that daily milk intake among Japanese men was associated with delayed and lower risk of mortality from stroke especially cerebral infarction.

Whey Protein and Its Components Lactalbumin and Lactoferrin Affect Energy Balance and Protect against Stroke Onset and Renal Damage in Salt-Loaded, High-Fat Fed Male Spontaneously Hypertensive Stroke-Prone Rats

BACKGROUND

Whey protein (WH)-enriched diets are reported to aid in weight loss and to improve cardiovascular health. However, the bioactive components in whey responsible for causing such effects remain unidentified.

OBJECTIVE

We determined the effects of whey and its components [α-lactalbumin (LA) and lactoferrin (LF)] on energy balance, glucose tolerance, gut hormones, renal damage, and stroke onset in rats.

METHODS

Male spontaneously hypertensive stroke-prone (SHRSP) rats (age 8 wk) were fed isocaloric high-fat (40% kcal) and high-salt (4% wt/wt) diets (n = 8-10/group) and randomized for 8 wk to diets enriched as follows: control (CO): 15% kcal from egg albumin, 45% kcal from carbohydrate; WH: 20%kcal WH isolate + 15% kcal egg albumin; LA: 20% kcal LA  + 15% kcal egg albumin; or LF: 20% kcal lactoferrin + 15% kcal egg albumin. Measurements included energy balance (food intake, energy expenditure, and body composition), stroke-related behaviors, brain imaging, glucose tolerance, metabolic hormones, and tissue markers of renal damage. Data were analyzed by linear mixed models with repeated measures or 1-way ANOVA.

RESULTS

Diets enriched with WH, LA, or LF increased survival, with 25% of rats fed these diets exhibiting stroke-associated morbidity, whereas 90% of CO rats were morbid by 8 wk (P < 0.05). The nephritis scores of rats fed WH-, LA-, or LF-enriched diets were 80%, 92%, and 122% lower than those of COs (P = 0.001). The mRNA abundances of renin and osteopontin were 100-600% lower in rats fed WH-, LA-, or LF-enriched diets than in COs (P < 0.05). Urine albumin concentrations and albumin-to-creatinine ratios were 200% lower in rats fed LF-enriched diets than in COs (P < 0.05). Compared with COs, rats fed LF-enriched diets for 2-3 wk had food intake decreased by 29%, body weight decreased by 13-19%, lean mass decreased by 12-19%, and fat mass decreased by 20% (P < 0.001). Relative to COs, rats fed WH and LA had food intake decreased by 10% (P < 0.1), but COs had 12-45% lower weight than rats fed LA- and WH-enriched diets by 3 wk (P < 0.01). Compared with COs, rats fed WH-enriched diets increased energy expenditure by 7%, whereas, rats fed LA-enriched diets had energy expenditure acutely decreased by 7% during the first 4 d, and rats fed LF-enriched diets had energy expenditure decreased by 7-17% throughout the first week ( P < 0.001). Rats fed LA- and LF-enriched diets had blood glucose decreased by 14-19% (P < 0.05) and WH by 9% (P = 0.1), relative to COs. Compared with COs, rats fed LF had GIP decreased by 90% and PYY by 87% (P < 0.05).

CONCLUSION

Together, these findings indicate that whey and its components α-lactalbumin and lactoferrin improved energy balance and glycemic control, and protected against the onset of neurological deficits associated with stroke and renal damage in male SHRSP rats.

Dairy consumption and risk of functional disability in an elderly Japanese population: the Hisayama Study

BACKGROUND

Little is known about the association between dairy intake and risk of functional disability in the elderly.

OBJECTIVES

We examined the influence of dairy intake on the development of declining functional capacity and activities of daily living (ADL) in a prospective cohort study of an elderly population.

METHODS

A total of 859 community-dwelling Japanese residents, aged ≥65 y without functional disability, were followed up for 7 y. Functional capacity impairment was defined as a Tokyo Metropolitan Institute of Gerontology Index of Competence score of ≤12, and ADL disability was defined as a Barthel Index score of ≤95. Dairy intake was evaluated using a 150-item semiquantitative food frequency questionnaire, grouped into quartiles. The RR of dairy intake on incident functional disability was computed using a Poisson regression model.

RESULTS

The multivariable-adjusted RR of impaired functional capacity decreased significantly with increasing dairy intake levels (RR [95% CI]: quartile 1, 1.00 [reference]; quartile 2, 0.85 [0.71, 1.02]; quartile 3, 0.81 [0.68, 0.98]; and quartile 4, 0.74 [0.61, 0.90]; P-trend = 0.001). Regarding the three subscales of functional capacity, the inverse association between dairy intake and risk for impairment of intellectual activity and social role remained significant (P-trend = 0.0009 and 0.02, respectively), but such an association was not observed for instrumental ADL. The multivariable-adjusted risk of ADL disability also decreased weakly but significantly with elevating dairy intake (P-trend = 0.04). A similar association was seen for severity of functional disability (P-trend = 0.002). However, the magnitude of these associations was attenuated after further adjustment for protein intake.

CONCLUSION

Our findings suggest that higher dairy intake is associated with a lower risk of functional disability and its progression in the elderly, probably via an increase in protein intake.

High Dietary Saturated Fat is Associated with a Low Risk of Intracerebral Hemorrhage and Ischemic Stroke in Japanese but not in Non-Japanese: A Review and Meta-Analysis of Prospective Cohort Studies

AIM

The associations between dietary saturated fatty acids and the risks of stroke subtypes in cohort studies were examined by a meta-analysis of separate ethnic Japanese and non-Japanese cohorts, and causes of their difference were elucidated.

METHOD

Log hazard ratio (HR) with 95% confidence interval (CI) of the highest versus the lowest saturated fat intake from cohort studies were weighed by an inverse variance method to combine HRs.

RESULTS

Five studies of intracerebral hemorrhage and 11 studies/comparisons of ischemic stroke were selected. A meta-analysis of intracerebral hemorrhage excluding subarachnoid hemorrhage showed a strong inverse association in Japanese (n=3, HR=0.55, 95% CI 0.32-0.94) but not in non-Japanese (n=2, HR=0.98, 95% CI 0.62-1.53). A meta-analysis of ischemic stroke showed a mild inverse association in Japanese (n=4, HR=0.82, 95% CI 0.71-0.93) but not in non-Japanese (n=7, HR= 0.93, 95% CI 0.84-1.03). The effect size of saturated fat in reducing the risk of stroke in Japanese was stronger for intracerebral hemorrhage (45% reduction) than for ischemic stroke (18% reduction).

CONCLUSIONS

In Japanese but not in non-Japanese, a diet high in saturated fat is associated with a low risk of intracerebral hemorrhage and ischemic stroke. This may be due to differences in the range of intake of saturated fat, genetic susceptibility, incidence of lacunar infarction, and/or confounding factors such as dietary proteins. An intervention study targeting Japanese will be required to verify the causality.

Dietary Protein Intake and Stroke Risk in a General Japanese Population: The Hisayama Study

BACKGROUND AND PURPOSE

The influence of dietary protein intake on stroke risk is an area of interest. We investigated the association between dietary protein intake and stroke risk in Japanese, considering sources of protein.

METHODS

A total of 2400 subjects aged 40 to 79 years were followed up for 19 years. Dietary protein intake was estimated using a 70-item semiquantitative food frequency questionnaire. The risk estimates for incident stroke and its subtypes were calculated using a Cox proportional hazards model.

RESULTS

During the follow-up, 254 participants experienced stroke events; of these, 172 had ischemic stroke, and 58 had intracerebral hemorrhage. Higher total protein intake was significantly associated with lower risks of stroke and intracerebral hemorrhage (both P for trend <0.05). With regard to sources of protein, the risks of total stroke and ischemic stroke significantly decreased by 40% (95% confidence interval, 12%-59%) and 40% (5%-62%), respectively, in subjects with the highest quartile of vegetable protein intake compared with those with the lowest one. In contrast, subjects with the highest quartile of animal protein intake had a 53% (4%-77%) lower risk of intracerebral hemorrhage. Vegetable protein intake was positively correlated with intakes of soybean products, vegetable, and algae, whereas animal protein intake was positively correlated with intakes of fish, meat, eggs, and milk/dairy products. Both types of protein intakes were negatively correlated with intakes of rice and alcohol.

CONCLUSIONS

Our findings suggest that higher dietary protein intake is associated with a reduced risk of stroke in the general Japanese population.

Circulating biomarkers of dairy fat and risk of incident stroke in U.S. men and women in 2 large prospective cohorts

BACKGROUND

Previous observational studies of self-reported dairy product consumption and stroke risk have reported mixed findings. Few studies have used circulating biomarkers that provide objective measures of dairy fat intake.

OBJECTIVES

We tested the hypothesis that the circulating biomarkers of dairy fat, pentadecanoic acid (15:0), heptadecanoic acid (17:0), and trans palmitoleate (trans 16:1n-7), were associated with lower incidence of stroke, especially ischemic stroke. Secondarily, we evaluated 14:0, which is obtained from dairy products and beef, and also endogenously synthesized.

DESIGN

In participants from 2 large US cohorts (the Health Professionals Follow-Up Study: 51,529 men; the Nurses' Health Study: 121,700 women) with stored blood samples in 1993-1994 (n = 18,225) and 1989-1990 (n = 32,826), respectively, we prospectively identified 594 incident stroke cases (median follow-up: 8.3 y) and matched them 1:1 to risk-set-sampled control subjects by age, sex, race, and smoking. Total plasma and red blood cell (RBC) fatty acids were measured by using gas-liquid chromatography. Covariates were assessed by using validated questionnaires. Stroke events and subtypes were adjudicated by using medical records or other supporting documentation. We used conditional logistic regression to estimate associations of fatty acids with incident stroke, and cohort-specific findings were combined by inverse-variance weights.

RESULTS

After adjustment for demographic characteristics, lifestyle, cardiovascular disease risk factors, diet, and other circulating fatty acids, no significant associations with total stroke were seen for plasma 15:0 (pooled HR for highest compared with lowest quartiles: 0.85; 95% CI: 0.54, 1.33), 17:0 (0.99; 0.67, 1.49), trans 16:1 n-7 (0.89; 0.55, 1.45), or 14:0 (1.05; 0.62, 1.78). Results were similar for ischemic and hemorrhagic stroke subtypes, for RBC fatty acids, and in several different sensitivity analyses.

CONCLUSION

In 2 large prospective cohorts, circulating biomarkers of dairy fat were not significantly associated with stroke.