Studies suggest antioxidant-rich dark chocolate with at least 50 to 70 percent cacao enhances blood flow, improves gut health, and eases stress — all effects that may indirectly strengthen your immune system.
Dark chocolate is one of the anomalies of nutrition. Researchers have been intrigued by the bittersweet superfood for years, not only because it is incredibly delicious and satisfies your sweet tooth, but also because there are dozens of scientific studies suggesting there are an overwhelming number of health benefits in this nutrient- and antioxidant-rich treat.
“Chocolate would be delicious no matter its health properties. So, the idea that something so good can also be good for us is both appealing and compelling,” David L. Katz, MD, MPH, the president of True Health Initiative and the founding director of the Prevention Research Center at Yale University Griffin Hospital, who has spent much of his career studying the health benefits of chocolate. “Chocolate is the decisive rebuttal to the ‘If it’s good for me, it can’t taste good’ mentality.”
As for the science, dark chocolate is derived from Theobroma cacao, aka, the cacao tree. Dr. Katz says it’s a uniquely concentrated source of bioflavonoid antioxidants, ranking high on the ORAC (oxygen radical absorbance capacity) scale relative even to many fruits and vegetables.
In 2011, Katz coauthored a study published in Antioxidants & Redox Signaling focusing on the many benefits of the superfood. In it, he and his colleagues explained that cocoa powder contains up to 50 milligrams of polyphenols per gram, with a single serving containing more phenolic antioxidants than most foods and drinks, including apples, cranberry juice, red wine, and black tea. The main flavonols found in cocoa are epicatechin and catechin, as well as procyanidins, which provide the most antioxidants.
“In addition, cocoa is a concentrated source of fiber, magnesium, potassium, and arginine — an amino acid that helps blood vessels dilate,” Katz says. And then there are psychoactive compounds like theobromine, which may help explain chocolate’s unique allure as an aphrodisiac (the perfect Valentine’s Day treat), but that area remains under study, he points out.
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So how do flavonoids work such magic? Deanna Minich, PhD, the vice president of scientific affairs at Clean Program, whose study areas are human nutrition and medical sciences with a focus on the application of science in nutrition and lifestyle, explains that those phytonutrients or polyphenols called flavonoids (aka antioxidants derived from plants) essentially help blood vessels expand and relax. “You might imagine that when your brain and heart have enough oxygen and blood flow, they work better,” she points out.
An article published in December 2016 in the Journal of Nutritional Science linked the brain-boosting amino acids and plant-based compounds to a possible role in the prevention of cancer, improved heart health, and even weight loss. Previous research also suggests that dark chocolate may help stabilize blood pressure and positively influence gut microbiota, improving digestion and metabolism.
In addition to all the physical benefits, dark chocolate may be a boon to the mind. A study slated for publication in May 2021 in Food Chemistry focuses on the bioactive amino acids tryptophan, phenylalanine, and tyrosine, all of which may help shift our neurochemistry, resulting in that “feel good” effect that a piece of chocolate usually provides. Research published in November 2019 by the National Institutes of Health (NIH) found that dark chocolate may also improve memory and cognitive function.
Scientists have become increasingly interested in the relationship between dark chocolate and immunity. And, during the COVID-19 pandemic, providing our bodies with the tools to fight infection has never been more crucial.
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Does Dark Chocolate Improve Immunity?
Generally speaking, inflammation is the immune system’s response to an irritant. When inflammation is severe, it can trigger reactions in the body leading to more serious health issues. An article published in August 2016 in Oxidative Medicine and Cellular Longevity explains how oxidative stress, an imbalance between the production of reactive oxygen species (ROS) and their elimination by protective mechanisms, can encourage chronic inflammation.
As an October 2016 article in Oxidative Medicine and Cellular Longevity notes, the resulting inflammation has been established as a major factor for the progression of various chronic diseases and disorders — diabetes, cancer, cardiovascular diseases, eye disorders, arthritis, obesity, autoimmune diseases, and inflammatory bowel disease included.
The idea that dark chocolate could bolster immunity is founded in the science that antioxidants offer anti-inflammatory benefits. Specifically, polyphenols can inhibit molecular signaling pathways that are activated by oxidative stress, combating the effects. “Research has suggested that dark chocolate improves immune function because it is packed with flavonols,” explains Keri Gans, RDN, a nutrition consultant and the author of The Small Change Diet. “Flavonols specifically are known to have antioxidant and anti-inflammatory properties.”
Katz brings it back to blood flow. “Immunity is critically dependent on blood flow, and dark chocolate is known to improve flood flow by enhancing endothelial function, and perhaps by other mechanisms as well,” he says. “Antioxidants help with immunity because they protect our own cells while the immune system fights the ‘enemy.’”
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While Dr. Minich agrees that “more antioxidants are needed to keep oxidative stress and inflammatory processes at bay, both of which are connected to immune function,” she maintains that “no specific direct effect of dark chocolate on immune health in humans has been demonstrated.” For example, there is no direct evidence that dark chocolate can protect you against the common cold, flu, or novel coronavirus. But she does believe there could be an indirect relationship between dark chocolate and this type of immunity.
She points to a study published in Brain, Behavior, and Immunity in October 2016, which found that dark chocolate could reduce the inflammatory response to a stressor, and a study published in February 2020 in Nutrition that found cocoa improved chronic sleep disorders (CSDs) induced by psychophysiological stress by preventing disruption in circadian rhythms — in mice, at least. Studies in humans are needed.
Two of the most highly cited studies exploring the relationship between dark chocolate and immunity were conducted in 2018 by researchers from Loma Linda University in California, who examined how dark chocolate with a high concentration of cacao (minimally 70 percent cacao, 30 percent organic cane sugar) influenced stress levels, inflammation, mood, memory, and immunity. Subjects consumed “large amounts of cacao in doses as small as a regular-size chocolate bar” over short and long periods of time, reports Lee S. Berk, DrPH, an associate dean of research affairs at the School of Allied Health Professions at Loma Linda and a researcher in psychoneuroimmunology and food science who was the principal investigator on both studies. The higher the concentration of cacao, “the more positive the impact on cognition, memory, mood, immunity and other beneficial effects,” the researchers concluded.
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The fact that chocolate is a rich source of fiber doesn’t hurt either, as “a healthy microbiome” — the genetic material of the microbes that live in and outside of the body, including bacteria, fungi, and other microbes — “is crucial to balanced immune responses, and fiber is key to feeding the microbiome,” Katz points out. A study published in November 2020 in Nature suggests that a healthy gut positively affects immunity in humans.
Additionally, there could be a psychological aspect to the relationship between chocolate and immunity. “There are direct links between psychology and immunology,” Katz explains. “Chocolate confers a relaxing pleasure, which may offer independent benefit to the immune system.”
The Best Dark Chocolate to Support Your Immune System
Research is pretty unanimous in terms of what ingredient makes dark chocolate a superfood — and it’s not sugar. The cacao bean boasts an abundance of nutrients, so Minich suggests looking for “cacao” at the top of the ingredient list, rather than cocoa or chocolate, which are lower down on the “brown pyramid” of chocolate goodness. “From there, I would say that the higher number is better for percentage cacao or cocoa in a bar, and not to go under 70 percent,” she says. Clean Program offers a low glycemic index, plant-based, raw chocolate bar that is 70 percent chocolate with sea salt, Minich says.
Gans points out that “the higher the percentage of cacao, the more bitter the taste.” She suggests aiming for a minimum 50 percent cacao, “and make sure that either cacao or cocoa beans, cocoa mass, or chocolate liquor are listed first on the ingredient list.”
Katz recommends avoiding bars with any additives and opting for organic if possible. And, if you can avoid Dutch process (non-alkalized) chocolate, you will reap more antioxidants and nutrients; since a lot of brands are alkalized, this type of chocolate may be hard to find. One option is Vivani Organic Dark Chocolate ($32.28 for a pack of five bars, Amazon.com), a high-quality organic non-alkali-processed dark chocolate.
And, take sugar into consideration. “Remember dark chocolate still has added sugar and with that comes extra calories,” Gans points out. “One ounce (or one square from a standard bar) of dark chocolate contains about 155 calories, and for the average individual that’s perhaps too many.” Instead, she suggests sticking to half a serving, and getting most of your antioxidants from fruits and veggies instead.