The study, which was published in the journal JAMA Network Open, involved researchers from Brigham and Women's Hospital (BWH), Harvard Medical School (HMS), and the Harvard T.H. Chan School of Public Health (HSPH).
The researchers set out to discover why and how a Mediterranean diet can lower the risk of heart disease and stroke by studying a panel of 40 biomarkers which represented new and established biological contributors to heart disease.
Other randomized trials in Mediterranean countries and observational studies already confirmed a connection between a Mediterranean diet and a reduced risk of cardiovascular disease. However, the underlying mechanisms remain unclear.
Exploring how the Mediterranean diet improves heart health
In the study, researchers analyzed data from American women who followed a Mediterranean-type diet. The findings revealed that participants who consumed a diet full of plants and olive oil instead of meats and sweets had a 25 percent reduction in their risk of cardiovascular disease.
According to Dr. Shafqat Ahmad, the lead author and a research fellow at BWH and HSPH, the study has a strong public health message: "modest changes in known cardiovascular disease risk factors, particularly those relating to inflammation, glucose metabolism and insulin resistance, contribute to the long-term benefit of a Mediterranean diet on cardiovascular disease risk." He added that this discovery is crucial for the primary prevention of cardiovascular disease.
For this study, researchers referenced data from over 25,000 female health professionals who took part in the Women's Health Study. The volunteers accomplished food intake questionnaires and provided blood samples that were used to measure the biomarkers linked to heart disease. The researchers monitored the participants for 12 years.
The primary outcomes examined in the study included incidents of cardiovascular disease, which were defined as first events of heart attack, stroke, coronary arterial revascularization, and cardiovascular death. (Related: Heart-healthy Mediterranean diet reduces stroke risk by 60 percent.)
The researchers grouped the volunteers into three groups: low, middle, or upper Mediterranean diet intake. They found that 356 women in the middle group (3.8 percent) and 246 (3.8 percent) in the upper group experienced a cardiovascular event.
Compared with the low group where 428 women (4.2 percent) experienced a cardiovascular event, these results represent a relative risk reduction of 23 percent and 28 percent for the middle and upper groups, respectively. This benefit is similar in magnitude to statins or other preventive medications.
In addition, the researchers also observed changes in the following:
- Signals of inflammation – accounts for 29 percent of the cardiovascular disease risk reduction
- Glucose metabolism and insulin resistance – accounts for 27.9 percent of the cardiovascular disease risk reduction
- Body max index – accounts for 27.3 percent of the cardiovascular disease risk reduction
Risk reduction was also linked to blood pressure, different forms of cholesterol, branch-chain amino acids, and other biomarkers. However, these accounted for less of the association between Mediterranean diet and cardiovascular risk reduction.
Dr. Samia Mora, the corresponding author of the study and a cardiovascular medicine specialist at BWH and HMS, said that even though earlier studies revealed how the Mediterranean diet reduced cardiovascular events and improved cardiovascular risk factors, not much is known about how improvements in known and novel risk factors contribute to these effects.
Mora concluded that through this large study, the researchers discovered that modest differences in biomarkers contributed in a multi-factorial way to this cardiovascular benefit that was seen over the long term.
What to eat while on the Mediterranean diet
People following the Mediterranean diet avoid packaged, processed, and store-bought foods that are full of additives. You're allowed to consume meat, but you need to limit your intake to less than six ounces of red meat each week. Eat grass-fed meats for best results.
If you're curious about the foods that you can eat frequently while following this beneficial diet, check out the list below.
- Almonds – When eaten in moderation, protein-rich almonds promote weight loss. Eat a handful of almonds if you want to have a healthy snack, or add the nuts to a salad for a nutritious meal.
- Garlic – Garlic is full of flavor and it can fight bacteria and fungi. It's also full of vitamins like manganese and vitamin B6.
- Hummus – To make hummus, you need to blend cooked garbanzo beans (chickpeas), garlic, lemon juice, olive oil, tahini, and your preferred spice. Use hummus as a healthy dip or spread.
- Lemon – Lemon contains vitamin C and it can help you detox.
- Olives and extra virgin olive oil (EVOO) – Extra virgin olive oil is cold-pressed from olives and is full of monounsaturated fats. EVOO helps reduce your risk of heart disease and cancer.
- Quinoa – Quinoa is a versatile ingredient that's naturally gluten-free. The grain also contains protein and fiber.
- Wild salmon –Unlike Atlantic salmon that is farm-raised and soy-fed, wild salmon contains 39 grams of protein per serving. Wild salmon also has heart-healthy omega-3 fatty acids.
Follow the Mediterranean diet if you want to stay healthy and lower your risk of developing cardiovascular disease.
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