After conducting a systematic review and meta-analysis of 61 controlled trials, Michael Falk from Life Sciences Research Organisation in US, found that consuming tree nuts lowers total cholesterol, triglycerides, LDL (bad) cholesterol, and ApoB, the primary protein found in LDL cholesterol.
These are key factors that are used to evaluate a person's risk of cardiovascular disease. Walnuts were investigated in 21 of the 61 trials, more than any other nut reviewed in this study, researchers said.
"Our study results further support the growing body of research that tree nuts, such as walnuts, can reduce the risk of cardiovascular diseases," said Falk.
Beyond finding that tree nuts lower total cholesterol, triglycerides, LDL cholesterol and ApoB, researchers also found that consuming at least two servings (two ounces or 57 grammes) per day of tree nuts, such as walnuts, has stronger effects on total cholesterol and LDL.
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Additionally, results showed that tree nut consumption may be particularly important for lowering the risk of heart disease in individuals with type 2 diabetes.
Trials directly provided nuts to the intervention group rather than relying solely on dietary advice to consume nuts.
The dose of nuts varied from 5 to 100g/day and most participants followed their typical diet.
More than two decades of research has shown that walnuts may help lower cardiovascular risk factors by decreasing LDL (bad) cholesterol by 9-16 per cent and diastolic blood pressure by 2-3 mmHg, as well as reducing total cholesterol, raising HDL cholesterol, reducing inflammation as measured by C-reactive protein, and improving arterial function.
In addition to providing omega-3s, walnuts also deliver a convenient source of fibre (2 grammes per ounce) and protein (4 grams per ounce).