Evidence that chocolate and other products that contain cocoa can help to reduce high blood pressure is not strong enough to warrant an official health claim in the US, according to a team of Canadian researchers.
A number of studies in recent years have concluded that compounds found in cocoa known as flavanols can lower blood pressure. Cocoa is one of the richest known sources of flavanols, a major class of plant phytochemicals known as flavonoids. The chocolate and cocoa industries also claim that their products have health benefits, in order to build reputation and meet the demand of health-conscious consumers.
In 2012 the European Food Safety Authority (EFSA) approved a claim that a daily 200mg of cocoa flavanols help maintain endothelium dependent vasodilation which contributes to normal blood flow (EFSA, 2012), but no health claim exists in the US.
Three types of claims exist in the US: health claims, nutrient content claims, and structure/function claims. Health claims, which are the focus of the Canadian review, describe a relationship between a food substance and a disease or a health-related condition (US FDA, 2018). Under the Nutrition Labeling and Education Act of 1990, the FDA may authorize health claims if there is significant scientific agreement (SSA) among qualified experts that a substance and disease relationship is valid.
Under the Food and Drug Administration Modernization Act of 1997, a new health claim can be authorized if other scientific bodies of the US government conclude that the evidence meets the SSA standard. In contrast to authorized health claims, qualified health claims are issued if they are supported by credible evidence but do not meet SSA standard. Qualified health claims are also issued with a letter of enforcement discretion, which specifies qualifying languages that reflect the level of evidence supporting the claim, as well as conditions where the qualified health claim can be used (US FDA, 2018). All health claims require pre-approval by the FDA.
In a paper published in Trends in Food Science and Technology, researchers concluded that the evidence that flavanols can lower blood pressures is weaker than has been claimed.
Authors Yidi Wanga, Bradley Felthama, Miyoung Suha and Peter Jones, who work at the Department of Food and Human Nutritional Sciences at University of Manitoba, Division of Neurodegenerative Disorders, Canadian Centre for Agri-Food Research in Health and Medicine and Richardson Centre for Functional Foods and Nutraceuticals at University of Manitoba, noted that the main mechanism by which cocoa flavanols reduce BP is increasing nitric oxide.
“With a high prevalence of hypertension in the North America, a health claim petition on cocoa flavanols may be considered within the US framework, in order to allow people to make better food choices,” they said. “The objective of this review was to evaluate whether there is sufficient evidence to support a blood pressure-lowering health claim for cocoa flavanols under the US Food and Drug Administration’s (FDA’s) jurisdiction.”
Seventeen human intervention studies examining the effect of cocoa flavanols on blood pressure were identified, with nine studies in normotensive participants, and eight studies in hypertensive participants. All studies were assessed for methodological quality based on the outline provided by the FDA.
Among the key findings and conclusions of the Canadian study were that nine out of the 17 studies reported a blood pressure-lowering effect of cocoa flavanols. “This indicates the evidence of cocoa flavanols on blood pressure reduction was conflicting,” they said. “Only a few studies presented as high quality. The optimal dose of cocoa flavanols and long-term effect of cocoa flavanols on blood pressure remain to be clarified.
“Therefore, within the US health claims system, an authorised health claim should not be passed, but a qualified health claim that is supported by low evidence may be attributed to cocoa flavanols and BP reduction.”