Del caffè e dei suoi effetti sull’organismo se ne sono sentite davvero di tutti i colori. C’è chi sostiene che la bevanda sia nemica del cuore e chi, al contrario, afferma che addirittura sia benefica in tal senso, aiutando a tenere sotto controllo le aritmie cardiache. Numerosi sono comunque stati, negli ultimi anni, gli studi sulle proprietà e gli effetti del caffè.
Tra gli effetti del caffè più studiati ci sono le sue proprietà antidolorifiche, dato che la caffeina potenzia l’azione dei classici analgesici, soprattutto nel contrastare il mal di testa. Grazie inoltre alle sue proprietà antiossidanti, dovute alla presenza di polifenoli, il caffè svolge anche un’azione preventiva sulle malattie cardiovascolari sullo scompenso cardiaco, sull’ipertensione, sulla riduzione della colesterolemia e sulle infiammazioni, sfatando quindi il mito del caffè pericoloso per il cuore.
Bisogna però ricordarsi che, solo qual ora il caffè venga preparato lasciando la polvere in infusione nell’acqua (caffè americano) e assunto ad alte dosi, il passaggio nella soluzione di alcuni composti lipidici chiamati diterpeni può alzare i livelli di colesterolo nel sangue. Tuttavia, la tradizionale preparazione “all’italiana” del caffè – che non lascia in infusione la polvere nell’acqua ma ne estrae le essenze aromatiche – fa sì che i componenti dannosi non passano nella bevanda. In questo senso, è inutile chiedere il decaffeinato, dato che il processo per eliminare la caffeina lascia inalterati i diterpeni.
Gli effetti negativi del caffè su cuore e coronarie non sono mai state dimostrate su studi di popolazione, ma solo su alcuni gruppi di individui particolarmente sensibili alla caffeina, per i quali si evidenziano, oltre le 7-8 tazzine al giorno azione prevalentemente gastriche (acidità) o cronotrope (tachicardia). Ma bisogna ricordare appunto che, nella popolazione generale esista la dimostrazione di come l’assunzione del caffè sia addirittura inversamente correlato al rischio di sviluppare insufficienza cardiaca, ipertensione e dislipidemia con grande beneficio dalle 4 tazzine in su!
Le persone che soffrono di acidità gastrica dovrebbero invece preferire il decaffeinato, anche se in questo caso sarebbe meglio eliminare dalla dieta tutte le bevande che contengono caffeina (come ad esempio la cola ma anche il tè), nonché diminuire il volume dei pasti e ridurre la quantità di bevande gassate e alcoliche.
Al contrario, le persone che fanno fatica a digerire troveranno giovamento dal classico caffè di fine pasto: stimola la produzione della bile e losvuotamento della cistifellea, e addirittura sembra possedere un effetto preventivo sulle malattie del fegato.
Chi soffre di mal di pancia o di stitichezza farebbe comunque bene ad evitare il caffè, considerati i suoi effetti negativi sull’intestino, tali da farcontrarre la muscolatura intestinale e da facilitare la perdita di liquidi tramite un’azione diuretica. Ragion per cui il caffè vanta anche un effetto lipolitico, cioè favorisce il dimagrimento: la caffeina stimola l’utilizzo dei grassi a scopo energetico e la termogenesi, aumentando la quantità di calorie bruciate.
Il caffè ha effetti anche sul sistema nervoso. In particolare, le sue proprietà stimolanti lo rendono adatto nel dare una carica di energia e una rapida sveglia quando si desidera essere subito efficienti dopo una pausa. Effetti positivi del caffè si riscontrano anche sull’attenzione e sulla memoria, anche se in alcuni casi può provocare crisi d’ansia o palpitazioni intense. Chi è predisposto all’insonnia, invece, farebbe meglio a bere il decaffeinato.
Tornando agli effetti positivi, altri studi hanno invece confermato che il caffè svolge anche un’azione protettiva verso le malattie degenerative del sistema nervoso, come l’alzheimer e il parkinson.
In definitiva, si può affermare con sicurezza quello che molti amanti del caffè sospettano già da tempo: il caffè aiuta la salute del cuore e del sistema cardiovascolare. Può avere effetti invece controversi sullo stomaco e sul tubo digerente essendo utile per la digestione ma potenzialmente irritante la mucosa gastrica per chi soffre di gastrite. Infine sul sistema nervoso può, in dosi appropriate, stimolare l’apprendimento e la memoria contribuendo alla protezione delle malattie degenerative del sistema nervoso centrale, mentre una quantità maggiore può, soprattutto a chi è sensibile, indurre ansia e agitazione.
Di seguito alcuni Abstract di articoli sullo studio degli effetti del caffè.
J Am Coll Cardiol. 2013 Sep 17;62(12):1043-51.
Effects of habitual coffee consumption on cardiometabolic disease, cardiovascular health, and all-cause mortality.
O’Keefe JH, Bhatti SK, Patil HR, DiNicolantonio JJ, Lucan SC, Lavie CJ.
Mid America Heart Institute at Saint Luke’s Hospital of Kansas City and University of Missouri-Kansas City, Kansas City, Missouri. Electronic address:firstname.lastname@example.org.
Coffee, after water, is the most widely consumed beverage in the United States, and is the principal source of caffeine intake among adults. The biological effects of coffee may be substantial and are not limited to the actions of caffeine. Coffee is a complex beverage containing hundreds of biologically active compounds, and the health effects of chronic coffee intake are wide ranging. From a cardiovascular (CV) standpoint, coffee consumption may reduce the risk of type 2 diabetes mellitus and hypertension, as well as other conditions associated with CV risk such as obesity and depression; but it may adversely affect lipid profiles depending on how the beverage is prepared. Regardless, a growing body of data suggests that habitual coffee consumption is neutral to beneficial regarding the risks of a variety of adverse CV outcomes including coronary heart disease, congestive heart failure, arrhythmias, and stroke. Moreover, large epidemiological studies suggest that regular coffee drinkers have reduced risks of mortality, both CV and all-cause. The potential benefits also include protection against neurodegenerative diseases, improved asthma control, and lower risk of select gastrointestinal diseases. A daily intake of ∼2 to 3 cups of coffee appears to be safe and is associated with neutral to beneficial effects for most of the studied health outcomes. However, most of the data on coffee’s health effects are based on observational data, with very few randomized, controlled studies, and association does not prove causation. Additionally, the possible advantages of regular coffee consumption have to be weighed against potential risks (which are mostly related to its high caffeine content) including anxiety, insomnia, tremulousness, and palpitations, as well as bone loss and possibly increased risk of fractures.
Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved
Circ Heart Fail. 2012 Jul 1;5(4):401-5. doi: 10.1161/CIRCHEARTFAILURE.112.967299. Epub 2012 Jun 26.
Habitual coffee consumption and risk of heart failure: a dose-response meta-analysis.
Mostofsky E, Rice MS, Levitan EB, Mittleman MA.
Cardiovascular Epidemiology Research Unit, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
There have been discrepant findings on the association between coffee consumption and risk of incident heart failure.
METHODS AND RESULTS:
We conducted a systematic review and a dose-response meta-analysis of prospective studies that assessed the relationship between habitual coffee consumption and the risk of heart failure. We searched electronic databases (MEDLINE, Embase, and CINAHL) from January 1966 through December 2011, with the use of a standardized protocol. Eligible studies were prospective cohort studies that examined the association of coffee consumption with incident heart failure. Five independent prospective studies of coffee consumption and heart failure risk, including 6522 heart failure events and 140 220 participants, were included in the meta-analysis. We observed a statistically significant J-shaped relationship between coffee and heart failure. Compared with no consumption, the strongest inverse association was seen for 4 servings/day and a potentially higher risk at higher levels of consumption. There was no evidence that the relationship between coffee and heart failure risk varied by sex or by baseline history of myocardial infarction or diabetes.
Moderate coffee consumption is inversely associated with risk of heart failure, with the largest inverse association observed for consumption of 4 servings per day.
Letter by Palatini regarding article, “Habitual coffee consumption and risk of heart failure: a dose-response meta-analysis”. [Circ Heart Fail. 2012
Pol Merkur Lekarski. 2013 Sep;35(207):133-5.
[The effect of coffee on blood pressure at healthy subjects].
[Article in Polish]
Bielesz K, Strzelczyk W, Poniewaz M, Sokołowski F, Welsyng D, Rucińska M, Nawrocki S.
Students’ Group in association with Department of Oncology, Medical University of Warmia and Mazury in Olsztyn, Poland.
Coffee is one of the most popular beverages. Its stimulatory effects comes from the natural alkaloid- caffeine. Caffeine is the antagonist of the adenosine receptors A1 and A2. Caffeine acts chronotropic positive and increases heart action; inotropic positive and increases cardiac contraction; tronotropic positive and increases hearts muscular ton, brain’s vascular stenosis, vasodilatation of coronal vessels, renal vessels, muscular vessels and skin vessels. The aim of the study was determination of coffee effect on blood pressure in healthy subjects.
MATERIAL AND METHODS:
17 healthy subjects (age 22-44 years; median 22 years) was included. There were two experiments. Experiment 1: examined persons drank instant coffee with or without caffeine. Experiment 2: examined persons drank natural coffee with or without caffeine. The blood pressure and pulse were examined before coffee drinking and 15 and 30 minutes after (in experiment 1) and only 30 minutes after (in experiment 2).
The blood pressure was increased on 10 mmHg or more in 9-40% of examined subjects in all groups, but there were no significant difference between groups. The pulse increased (10 or more per minute) was observed only in one person and decrease was observed in three who drank natural coffee with caffeine.
In healthy subjects the blood pressure does not increased significantly after caffeine consumption. The consumption of caffeine in large doses may be harmful to some hypertensive or hypertension-prone subjects.
Caffeine does not increase the risk of atrial fibrillation: a systematic review and meta-analysis of observational studies.
Caldeira D, Martins C, Alves LB, Pereira H, Ferreira JJ, Costa J.
Laboratory of Clinical Pharmacology and Therapeutics, Faculty of Medicine, University of Lisbon, Lisboa, Portugal. email@example.com
Atrial fibrillation (AF) is the most prevalent sustained arrhythmia, and risk factors are well established. Caffeine exposure has been associated with increased risk of AF, but heterogeneous data exist in the literature.
To evaluate the association between chronic exposure to caffeine and AF.
Systematic review and meta-analysis of observational studies.
PubMed, CENTRAL, ISI Web of Knowledge and LILACS to December 2012. Reviews and references of retrieved articles were comprehensively searched.
Two reviewers independently searched for studies and retrieved their characteristics and data estimates.
Random-effects meta-analysis was performed, and pooled estimates were expressed as OR and 95% CI. Heterogeneity was assessed with the I(2) test. Subgroup analyses were conducted according to caffeine dose and source (coffee).
Seven observational studies evaluating 115 993 individuals were included: six cohorts and one case-control study. Caffeine exposure was not associated with an increased risk of AF (OR 0.92, 95% CI 0.82 to 1.04, I(2)=72%). Pooled results from high-quality studies showed a 13% odds reduction in AF risk with lower heterogeneity (OR 0.87; 95% CI 0.80 to 0.94; I(2)=39%). Low-dose caffeine exposure showed OR 0.85 (95% CI 0.78 to 92, I(2)=0%) without significant differences in other dosage strata. Caffeine exposure based solely on coffee consumption also did not influence AF risk.
Caffeine exposure is not associated with increased AF risk. Low-dose caffeine may have a protective effect.
Nutr Metab (Lond). 2013 Oct 3;10(1):61. doi: 10.1186/1743-7075-10-61.
Coffee polyphenols exert hypocholesterolemic effects in zebrafish fed a high-cholesterol diet.
Meguro S, Hasumura T, Hase T.
Hypercholesterolemia is an important risk factor for the development of coronary artery disease. Some dietary polyphenols, such as coffee polyphenols (CPPs), reduce cholesterol levels. The mechanism of this cholesterol-lowering effect is not fully understood, although 5-CQA, a major component of CPPs, reportedly inhibits cholesterol biosynthesis. Here, we investigated the mechanism of the cholesterol-lowering effect of CPPs on the basis of cholesterol metabolism-related gene expression in the liver. We also examined the effects of CPPs on vascular lipid accumulation in zebrafish with high cholesterol diet-induced hypercholesterolemia.
Over 14 weeks, adult zebrafish were fed a control diet, a high-cholesterol diet, or the latter diet supplemented with CPPs. To measure the extent of vascular lipid accumulation, for 10 days larval zebrafish (which are optically transparent) were fed these same diets with the addition of a fluorescent cholesteryl ester.
In adult zebrafish, addition of CPPs to a high-cholesterol diet significantly suppressed the increase in plasma and liver cholesterol levels seen when fish ingested the same diet lacking CPPs. Transcription levels of the liver genes hmgcra (encoding 3-hydroxy-3-methylglutaryl-coenzyme A reductase A, a rate-limiting enzyme in cholesterol biosynthesis) and mtp (encoding microsomal triglyceride transfer protein, a lipid transfer protein required for assembly and secretion of lipoproteins) were significantly lower in fish fed the CPP-containing diet than in fish fed the unsupplemented high-cholesterol diet. In contrast, the expression level of the liver gene cyp7a1a (encoding the cytochrome P450 polypeptide 1a of subfamily A of family 7, a rate-limiting enzyme for bile acid biosynthesis) increased significantly upon consumption of the CPP-containing diet. In larval fish, accumulation of fluorescently labeled cholesterol in the caudal artery was greatly reduced on the CPP-containing diet.
CPP ingestion suppressed cholesterol accumulation in the plasma, liver, and vascular system of zebrafish. Downregulation of cholesterol and lipoprotein synthesis and upregulation of bile acid synthesis in the liver may be the fundamental underlying mechanisms by which CPPs exert their hypocholesterolemic effects. CPP intake may help prevent and manage hypercholesterolemia in humans, and further investigations along these lines using a variety of CPP dose rates are warranted.