The Effect of a Single Dose of Dark Chocolate on Cardiovascular Parameters and Their Reactivity to Mental Stress

The Cardiovascular Benefits of Dark Chocolate Supplementation before High-Intensity Resistance Exercise in the Early Follicular and Mid-Luteal Phases of the Menstrual Cycle

BACKGROUND

Dark chocolate, rich in flavanols, may support vascular health by reducing arterial stiffness and blood pressure across menstrual phases. This study examined the effects of 85% dark chocolate on nitric oxide (NO) levels and vascular function during high-intensity resistance exercise in healthy women across the early follicular and mid-luteal phases.

METHODS

Thirty-one healthy women (aged 20-30 years) with regular menstrual cycles completed a randomized, crossover study (conducted at National Chung Cheng University, Sep-Dec 2023). Participants consumed either 85% dark chocolate or milk chocolate (1 g/kg body weight) before high-intensity resistance exercise during the early follicular (days 2-5) and mid-luteal (days 18-24) phases of two menstrual cycles. Finger-toe pulse wave velocity (ftPWV), arterial stiffness, blood pressure, and plasma NO levels were measured at rest, 2 h after chocolate consumption (baseline), immediately post-exercise (T0), and at 60 (T60) and 120 (T120) minutes post-exercise.

RESULTS

Dark chocolate supplementation significantly increased NO levels and reduced systolic blood pressure (SBP), ftPWV, and arterial pressure volume index (API) (p < 0.05) compared to milk chocolate across both menstrual phases. During the early follicular phase, dark chocolate also attenuated exercise-induced increases in arterial stiffness and blood pressure (p < 0.05).

CONCLUSION

85% dark chocolate supplementation may reduce the negative vascular effects of high-intensity resistance exercise, particularly by lowering blood pressure, arterial stiffness, and API, especially in the early follicular phase. These findings suggest that dark chocolate could be a practical, non-pharmacological intervention for improving cardiovascular health in women.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT06908941. Registered 19 March 2025 - Retrospectively registered, https://clinicaltrials.gov/study/NCT06908941 .

Intake of Dark and Milk Chocolate Differently Affects Autonomic Nervous Control of the Heart During Rest and Mental Stress

OBJECTIVE

Chocolate is a popular food that may affect the activity of the autonomic nervous system (ANS). The aim of this study was to determine the effect of a single dose of dark or milk chocolate on ANS cardiac control during rest and mental stress induced by the Stroop test (ST).

METHODS

Healthy participants, divided into DARK or MILK chocolate groups, ingested corresponding type of chocolate (1 g/kg body weight). They underwent measurement of ANS during relaxation and ST before and 2 h after chocolate consumption. ANS control was assessed by determination of heart rate (HR) and heart rate variability using parameters related to complex autonomic modulation (TP, SDNN) or primary vagal modulation (HFnu, RMSSD).

RESULTS

HR was always increased during ST in both groups. Relaxation HR values after chocolate ingestion were higher only in the DARK chocolate group. During ST, values of TP, SDNN and HFnu decreased before and after chocolate ingestion in the DARK group, but only before chocolate ingestion in the MILK group. RMSSD values decreased during ST before and after chocolate ingestion in both groups. Relaxation TP, RMSSD and HFnu values after chocolate ingestion were lower in the DARK but not in the MILK group.

CONCLUSION

The results suggest that even a single dose of milk chocolate attenuates changes in ANS cardiac control induced by mental stress, whereas a single dose of dark chocolate has an activating effect on the heart via modification of ANS cardiac control at rest. Different levels of sugars and cocoa biologically active compounds in the two types of chocolate could explain the observed effects.

Results of the BfR MEAL Study: Acrylamide in foods from the German market with highest levels in vegetable crisps

Acrylamide (AA) is formed in foods due to thermal processes. AA was analysed in 230 foods in the first German Total Diet Study and the highest mean levels of AA were found in vegetable crisps (1430 μg/kg), followed by potato pancakes (558) μg/kg) and pan-fried potatoes (450 μg/kg). In various foods, e.g. French fries and sweet potatoes, AA was also tested for different browning degrees and cooking methods. French fries cooked to a browning degree of 3 in all cooking methods exceeded the benchmark level set by the European Union. French fries prepared in the oven and sweet potatoes in the air fryer had the lowest AA levels. In foods from the German market, AA was found also in foods such as popcorn (243 μg/kg), salty sticks (190 μg/kg), and dark chocolate (130 μg/kg). Levels of AA found in our study may support future dietary exposure and food safety assessments.

Chronic and postprandial effect of blueberries on cognitive function, alertness, and mood in participants with metabolic syndrome - results from a six-month, double-blind, randomized controlled trial

BACKGROUND

Anthocyanin and blueberry intakes positively associated with cognitive function in population-based studies and cognitive benefits in randomized controlled trials of adults with self-perceived or clinical cognitive dysfunction. To date, adults with metabolic syndrome (MetS) but without cognitive dysfunction are understudied.

OBJECTIVES

Cognitive function, mood, alertness, and sleep quality were assessed as secondary end points in MetS participants, postprandially (>24 h) and following 6-mo blueberry intake.

METHODS

A double-blind, randomized controlled trial was conducted, assessing the primary effect of consuming freeze-dried blueberry powder, compared against an isocaloric placebo, on cardiometabolic health >6 mo and a 24 h postprandial period (at baseline). In this secondary analysis of the main study, data from those completing mood, alertness, cognition, and sleep assessments are presented (i.e., n = 115 in the 6 mo study, n = 33 in the postprandial study), using the following: 1) Bond-Lader self-rated scores, 2) electronic cognitive battery (i.e., testing attention, working memory, episodic memory, speed of memory retrieval, executive function, and picture recognition), and 3) the Leeds Sleep Evaluation Questionnaire. Urinary and serum anthocyanin metabolites were quantified, and apolipoprotein E genotype status was determined.

RESULTS

Postprandial self-rated calmness significantly improved after 1 cup of blueberries (P = 0.01; q = 0.04; with an 11.6% improvement compared with baseline between 0 and 24 h for the 1 cup group), but all other mood, sleep, and cognitive function parameters were unaffected after postprandial and 6-mo blueberries. Across the ½ and 1 cup groups, microbial metabolites of anthocyanins and chlorogenic acid (i.e., hydroxycinnamic acids, benzoic acids, phenylalanine derivatives, and hippuric acids) and catechin were associated with favorable chronic and postprandial memory, attention, executive function, and calmness.

CONCLUSIONS

Although self-rated calmness improved postprandially, and significant cognition-metabolite associations were identified, our data did not support strong cognitive, mood, alertness, or sleep quality improvements in MetS participants after blueberry intervention. This trial was registered at clinicaltrials.gov as NCT02035592.

A comprehensive insight into the molecular effect of theobromine on cardiovascular-related risk factors: A systematic review of in vitro and in vivo studies

Theobromine may have beneficial effects on cardiovascular risk factors. This study aimed to find molecular effects of theobromine on lipid profile, glycemic status, inflammatory factors, and vascular function through a comprehensive assessment of all in vitro and in vivo studies. The search process was started at 18 July 2022. Databases including PubMed, Scopus, and Web of Science were searched to find all articles published up to 18 July 2022. Nineteen studies were included in this study. In vitro studies showed the improving effects of theobromine on inflammatory markers. Of four animal studies assessing the effect of theobromine on inflammatory markers, two reported favorable effects. Among five animal studies assessing the effects of theobromine on lipid profile, three reported improving effects on either triglyceride, total cholesterol, low- or high-density lipoprotein cholesterol. Of the three human studies, two revealed that theobromine had improving effects on lipid profile. A favorable effect of theobromine on augmentation index was also reported in two RCTs. The results for other outcomes were inconclusive. Theobromine may have favorable effects on inflammatory factors, lipid profile, and vascular function markers. However, studies with a longer duration and lower, dietary-relevant doses are required for future confirmation.

Dark chocolate (70% cocoa) attenuates the inflammatory marker TNF-α in patients on hemodialysis

BACKGROUND

Inflammation and oxidative stress lead to a high risk of cardiovascular disease in patients with chronic kidney disease (CKD). Food rich in polyphenols such as dark chocolate may be an effective strategy to mitigate inflammation and delay CKD complications, outwith sensorial pleasure promotion. The aim of this study was to evaluate the effects of dark chocolate on inflammation and oxidative stress markers in patients with CKD on hemodialysis (HD).

METHODS

A clinical trial was carried out with 59 patients who were allocated into the chocolate group [40g of dark chocolate (70% cocoa) offered during HD sessions, 3×/week] or the control group with any intervention for two months. Plasma levels of the inflammatory cytokines TNF-α and IL-6 were evaluated by the ELISA method. Thiobarbituric acid reactive substances such as malondialdehyde (MDA) and LDLox levels were evaluated as lipid peroxidation markers. Routine biochemical parameters were analysed using commercial BioClin® kits.

RESULTS

Thirty-five patients completed the chocolate group (18 men, 53.0 (16) years and 31.0 (39) months on HD) and 11 in the control group (7 men, 48.0 (17.5) years and 44.0 (56.5) months on HD). Regarding the differences between the groups, the patients who received dark chocolate had reduced plasma levels of TNF-α compared to the control (p = 0.008). No significant changes were observed in the oxidative stress parameters evaluated in both groups. Routine biochemical (including phosphorus and potassium levels) and anthropometric parameters and food intake were not changed after the study period.

CONCLUSION

The intervention with dark chocolate (70% cocoa) for two months reduced the plasma levels of TNF-α in patients with CKD on HD. In addition, it is essential to emphasise that chocolate intake did not increase the plasma levels of phosphorus and potassium in these patients. This study was registered at clinicaltrials.gov as NCT04600258.

(-)-Epicatechin Reverses Glucose Intolerance in Rats Housed at Thermoneutrality

Diabetes is a life-threatening and debilitating disease with pathological hallmarks, including glucose intolerance and insulin resistance. Plant compounds are a source of novel and effective therapeutics, and the flavonoid (-)-epicatechin, common to popular foods worldwide, has been shown to improve carbohydrate metabolism in both clinical studies and preclinical models. We hypothesized that (-)-epicatechin would alleviate thermoneutral housing-induced glucose intolerance. Male rats were housed at either thermoneutral (30 °C) or room temperature (24 °C) for 16 weeks and gavaged with either 1 mg/kg body weight or vehicle for the last 15 days before sacrifice. Rats housed at thermoneutrality had a significantly elevated serum glucose area under the curve (p < 0.05) and reduced glucose-mediated insulin secretion. In contrast, rats at thermoneutrality treated with (-)-epicatechin had improved glucose tolerance and increased insulin secretion (p < 0.05). Insulin tolerance tests revealed no differences in insulin sensitivity in any of the four groups. Pancreatic immunohistochemistry staining showed significantly greater islet insulin positive cells in animals housed at thermoneutrality. In conclusion, (-)-epicatechin improved carbohydrate tolerance via increased insulin secretion in response to glucose challenge without a change in insulin sensitivity.

Cardiovascular Effects of Chocolate and Wine-Narrative Review

The consumption of food for pleasure is mainly associated with adverse health effects. This review was carried out to verify recent reports on the impact of chocolate and wine consumption on cardiovascular health, with a particular focus on atherosclerosis. On one side, these products have proven adverse effects on the cardiovascular system, but on the other hand, if consumed in optimal amounts, they have cardiovascular benefits. The submitted data suggest that the beneficial doses are 30–50 g and 130/250 mL for chocolate and wine, respectively, for women and men. The accumulated evidence indicates that the active ingredients in the products under consideration in this review are phenolic compounds, characterized by anti-inflammatory, antioxidant, and antiplatelet properties. However, there are also some reports of cardioprotective properties of other compounds such as esters, amines, biogenic amines, amino acids, fatty acids, mineral ingredients, and vitamins. Our narrative review has shown that in meta-analyses of intervention studies, consumption of chocolate and wine was positively associated with the beneficial outcomes associated with the cardiovascular system. In contrast, the assessment with the GRADE (Grading of Recommendations Assessment, Development and Evaluation) scale did not confirm this phenomenon. In addition, mechanisms of action of bioactive compounds present in chocolate and wine depend on some factors, such as age, sex, body weight, and the presence of additional medical conditions. Patients using cardiovascular drugs simultaneously with both products should be alert to the risk of pharmacologically relevant interactions during their use. Our narrative review leads to the conclusion that there is abundant evidence to prove the beneficial impact of consuming both products on cardiovascular health, however some evidence still remains controversial. Many authors of studies included in this review postulated that well-designed, longitudinal studies should be performed to determine the effects of these products and their components on atherosclerosis and other CVD (Cardiovascular Disease) disease.