Vietnamese Doctor Warns on Coffee's Health Benefits - Limited Impact on Blood Sugar and Cholesterol

A Vietnamese medical expert has cautioned against overestimating the health benefits of daily unsweetened black coffee, stating its impact on controlling blood sugar and cholesterol, and improving liver health is limited. Dr. Nguyen Thanh Phong, PhD, Specialist Doctor Level II, Head of the Outpatient Department at An Sinh Hospital, told VnExpress that while unsweetened black coffee can be part of a healthy diet for most people, it should not be considered a treatment for high blood sugar, abnormal blood lipids, or liver disease. Long-term observational studies have found that habitual coffee drinkers tend to have a lower risk of developing Type 2 diabetes. However, Dr. Phong emphasized that this association does not prove that coffee itself prevents the disease. In the short term, caffeine may temporarily reduce insulin sensitivity and cause blood sugar to rise slightly after meals in some individuals, meaning coffee should not be expected to immediately stabilize glucose levels. For blood lipids, the brewing method matters. Unfiltered or boiled coffee contains compounds like cafestol and kahweol, which can raise total cholesterol and LDL ('bad') cholesterol. Paper-filtered coffee, on the other hand, has significantly lower levels of these compounds as most are trapped by the filter. Coffee consumption has also been associated with a lower risk of fatty liver disease and cirrhosis. However, clinical trials have not established clear evidence that it directly reduces liver enzymes such as ALT and AST. Dr. Phong advised that people who do not normally drink coffee do not need to start simply in hopes of improving their blood test results. A moderate amount of properly filtered, unsweetened black coffee can fit into a balanced lifestyle, but it has no proven role as a medical treatment. Long-term metabolic health still depends primarily on a healthy diet, maintaining an appropriate weight, regular physical activity, adequate sleep, and limiting alcohol consumption, Dr. Phong concluded.