The polyphenol fraction of extra-virgin olive oil may be partly responsible for its cardioprotective effects. The aim of this systematic review and meta-analysis was to evaluate the effect of high versus low polyphenol olive oil on cardiovascular disease (CVD) risk factors in clinical trials. In accordance with PRISMA guidelines, CINAHL, PubMed, Embase and Cochrane databases were systematically searched for relevant studies. Randomized controlled trials that investigated markers of CVD risk (e.g. outcomes related to cholesterol, inflammation, oxidative stress) were included. Risk of bias was assessed using the Jadad scale. A meta-analysis was conducted using clinical trial data with available CVD risk outcomes. Twenty-six studies were included. Compared to low polyphenol olive oil, high polyphenol olive oil significantly improved measures of malondialdehyde (MD: -0.07µmol/L [95%CI: -0.12, -0.02µmol/L]; I: 88%; p = 0.004), oxidized LDL (SMD: -0.44 [95%CI: -0.78, -0.10µmol/L]; I: 41%; P = 0.01), total cholesterol (MD 4.5 mg/dL [95%CI: -6.54, -2.39 mg/dL]; p<0.0001) and HDL cholesterol (MD 2.37 mg/dL [95%CI: 0.41, 5.04 mg/dL]; p = 0.02). Subgroup analyses and individual studies reported additional improvements in inflammatory markers and blood pressure. Most studies were rated as having low-to-moderate risk of bias. High polyphenol oils confer some CVD-risk reduction benefits; however, further studies with longer duration and in non-Mediterranean populations are required.

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. In the absence of effective pharmacotherapies, clinical guidelines focus primarily on weight loss to treat this condition. Established consensus, evidence-based, and clinical dietary recommendations for NAFLD are currently lacking. The aim of this paper is to provide evidence-based practical dietary recommendations for the prevention and management of NAFLD in adults. A literature review focusing on established principles for the development of clinical practice recommendations was employed using the following criteria: based on substantial evidence, ensures risk minimization, is flexible for an individual patient approach, and is open to further modification as evidence emerges. The Practice-based Evidence in Nutrition classification system was used to grade these principles. Five key dietary recommendations were developed: 1) follow traditional dietary patterns, such as the Mediterranean diet; 2) limit excess fructose consumption and avoid processed foods and beverages with added fructose; 3) PUFAs, especially long-chain omega-3 rich foods and MUFAs, should replace SFAs in the diet; 4) replace processed food, fast food, commercial bakery goods, and sweets with unprocessed foods high in fiber, including whole grains, vegetables, fruits, legumes, nuts, and seeds; and 5) avoid excess alcohol consumption. Improving diet quality may reduce the incidence and progression of NAFLD and associated risk factors. Many of the benefits are likely to result from the collective effect of dietary patterns. High-quality research-in particular, randomized clinical trials assessing dietary interventions that focus on liver-specific endpoints-are needed as a priority.

A higher dietary inflammatory index (DII®) score is associated with inflammation and incidence of coronary heart disease (CHD). We hypothesized that a Mediterranean diet (MedDiet) intervention would reduce DII score. We assessed dietary data from a randomized controlled trial comparing 6-month MedDiet versus low-fat diet intervention, in patients with CHD. We aimed to determine the DII scores of the prescribed diets' model meal plans, followed by whether dietary intervention led to lower (i.e., more anti-inflammatory) DII scores and consequently lower high sensitivity C-reactive protein (hs-CRP) and interleukin-6 (hs-IL-6). DII scores were calculated from 7-day food diaries. The MedDiet meal plan had a markedly lower DII score than the low-fat diet meal plan (-4.55 vs. -0.33, respectively). In 56 participants who completed the trial (84% male, mean age 62 ± 9 years), the MedDiet group significantly reduced DII scores at 6 months (n = 27; -0.40 ± 3.14 to -1.74 ± 2.81, P = .008) and the low-fat diet group did not change (n = 29; -0.17 ± 2.27 to 0.05 ± 1.89, P = .65). There was a significant post-intervention adjusted difference in DII score between groups (compared to low-fat, MedDiet decreased by -1.69 DII points; P = .004). When compared to the low-fat diet, the MedDiet non-significantly reduced hs-IL-6 (-0.32 pg/mL, P = .29) and increased hs-CRP (+0.09 mg/L, P = .84). These findings demonstrated that MedDiet intervention significantly reduced DII scores compared to a low-fat diet. However, in this small cohort of patients with CHD this did not translate to a significant improvement in measured inflammatory markers. The effect of improvement in DII with MedDiet should be tested in larger intervention trials and observational cohorts.