A commonly asked question posed by patients, their voices betraying an inner hope coupled with an expectation in their hearts, that we can affirm their craving for this food. Lathan and colleagues in this month's Journal, in their well-balanced and thoughtful review, succinctly organize and summarize the available data seeking to answer this question. Yet the answer to remains elusive and is far from complete.
Available published data does suggest some positive, perhaps hopeful, findings. Generally, it is possible to classify these findings into two broad categories—the preclinical and the clinical translation.
There are 3 fairly consistent preclinical findings: (1) increase in nitric oxide; (2) increase in flow-mediated vasodilatation; and (3) decrease in platelet aggregation.
The clinical translation is less consistent in all studied parameters: (1) Blood pressure (BP): the data are variable with some studies demonstrating very modest reductions in BP and others with no effect. (2) Lipid effects: high-flavanol chocolates generally demonstrate some consistency with positive effects on low-density lipoprotein (decrease) and high-density lipoprotein (increase).
The preclinical results may be linked via similar pathways and therefore are not independent findings but simply provide the fuel for further evaluation. Investigation has also attempted to identify the active compound(s) that result in these favorable findings. Speculation and data suggest that flavanols may contribute to a large extent to these results. Therefore, studies have attempted to use the relative flavanol content of various chocolate concoctions as the active comparator (high flavanol) and placebo (low flavanol) in the studies of chocolate.
Other clinical data are limited to the epidemiologic. Among several attempts to examine the potential benefits of chocolate published in the literature, one is interesting. That is the experience of the Kuna Indians, an island-dwelling tribe inhabiting the San Blas Islands of Panama. They exhibit low incidence of hypertension and cardiovascular disease. Perhaps of greater interest is the notable finding that theirs is one of the few cultures, without salt limitation, that fails to demonstrate an age-related increase in BP. On average they drink 32 ounces of unprocessed cocoa beverage daily. Unfortunately, most Americans and Europeans would find it difficult to consume this bitter, foreign cocoa preparation as it bears little resemblance to the sweetened chocolate and confections available for purchase here.
The results of the data are summarized above, but as the authors acknowledge, some serious concerns and reservations will and should impact the answer to our patients' questions regarding the health benefit of chocolate.
Six are the most obvious and worth mentioning.
- Publication bias. Positive results of studies get published while negative results are relegated to the back of the file cabinet, never to see the light of day or word in print. This is particularly an issue with studies that may be investigator-generated and not registered.
- Limited enrollment. Generally, only small numbers of patients were included in the study populations, with enrollees usually numbering in the low double digits. The largest study included in this review comprised only 152 patients, perhaps enough to suggest some statistical benefit, but insufficient to convince most.
- Short duration. The studies are typically short-term, lasting hours to days, with the longest study period lasting 18 weeks. Recommendations regarding long-term therapy require longer-term studies to demonstrate that efficacy continues with extended usage.
- Soft endpoints. The studies often incorporated surrogate soft endpoints (effects on nitric oxide, flow-mediated dilation, and platelet aggregation), with the assumptions that there may be a correlation with hard cardiovascular endpoints. These studies, although provocative, have often failed to demonstrate universal clinical correlation. Even modest BP reductions, when found and reported, have been seen in only a small number of patients for short periods. Additionally, the only metric used to determine BP were readings performed in the office.
- Double-blind issues. Challenges exist in the investigation of chocolate to achieve a true double-blind test. Chocolates have various tastes, colorations, and textures and any attempt to investigate the properties of one vs another must control for this. The value of single-blind studies needs to be proven.
- Translation. Flavanols are the putative active compound in chocolate that results in possible health benefit, but chocolate formulations are more varied than coffee. Broadly speaking, dark chocolates, bitter and less creamy and smooth, are of far greater benefit that the more pleasing to the American palate milk chocolate. Yet, patients will often attribute possible benefit of one to the other. Additionally, there is little in the way of standardization among chocolates to know the actual content of active compound in each sold product.
But why so much interest in chocolate?
This persistence of interest in chocolate is, no doubt, in no small part due to the appeal of chocolate itself. There is certainly not the same degree of interest among patients as to whether or not 8 daily Brussels sprouts might provide similar cardiovascular protection as chocolate. Chocolate is often associated with special occasions, holidays, and festivities. It is often displayed in boxes, wrapped, and meant to be something special, and, as such, evoke warm feelings in many, harkening back to earlier, happy times as a comfort food. Certainly this bears little resemblance to the “charms” of Brussels sprouts. Then there is the allure of chocolate itself, activating the senses of smell first. Then the satisfaction as the melting of the fats and cocoa on the tongue release the full flavor upon the taste buds sending message of satisfaction to the brain. As for Brussels sprouts—both the scent and the taste are “acquired” tastes. It is little wonder that it drives us to hope that chocolate may provide health benefits far beyond the satisfaction we derive with its consumption. While Brussels sprouts, despite their known nutritional value, languish, unloved and unconsumed.
It is also important to mention that chocolate is not without concerns. In societies that continue to struggle with weight and excess calories, to what extent might the additional calories consumed with extra chocolate adversely impact patients in the long-term? Given the challenges with reading labels and adhering to directions, might advising patients to consume chocolate do them much more harm than benefit? How many would substitute better-tasting (to them) and lower-priced generic chocolate for the higher-priced more bitter cocoa based product on the mistaken belief that chocolate is chocolate? Even among patients who recognize that dark chocolate is better than milk chocolate, there exists a great degree of variability in the flavanol content of these various chocolates, so how does one choose? To what extent might these even differ batch-to-batch and year-to-year as formulations may vary and lack rigid standardization.
One can expect that there will be an attempt to identify the active compound or ingredients. This will be followed by a desire to either extract, distill, or manufacture these active compounds, with the ultimate goal of making it available as a purified high-grade pharmaceutical product available in pill form. It will be suitable and convenient for daily consumption. It will not melt, will transport easily and in bulk, will be standardized in its formulation, providing the benefit, without the calories and perhaps the cost of the natural product. And although it may be of some benefit, it will lack the allure of chocolate, it will not stimulate and satisfy our senses of smell and taste, it will not evoke memories of happier times, and it will not satisfy our chocolate craving. And few patients will ask to take the “chocolate” pill.
At this time, the data are far from complete, the ingredients are mixed, and the finished product is expected but not ready to be served. For now, perhaps the best way to answer the question “Chocolate is good for me, right?” is with another question. Ask the patient what types of chocolate do they prefer. If they respond with milk chocolate or similar products (Hersey's Kisses, Milky Way, Snickers, and the like) then it is best to answer that it is not good for them and should be reserved for special occasions. If the answer is dark, bitter chocolates, then further discussion is warranted that outlines the data so well presented by Latham and colleagues.
As for myself, I am hoping that our plant scientists can find a way to make those Brussels sprouts sitting in my garden taste like, and satisfy the craving for, chocolate.