Flaxseeds, almonds, avocados, tomatoes, turmeric and green tea distinctly bring down LDL cholesterol

In a recent study, researchers evaluated several dietary foods and reported that each dietary food distinctly modifies LDL cholesterol levels. They reported that several novel foods can help to reduce LDL cholesterol which includes flaxseeds, almonds, avocados, tomatoes, turmeric, and green tea. The study findings were published in the journal Nutrition, Metabolism & Cardiovascular Diseases on January 15, 2022.

The potential for improvement in LDL cholesterol through diet is also substantial, as demonstrated by studies combining several foods, e.g. the Portfolio diet, which emphasizes nuts, plant protein, plant sterols, and soluble fibre. In recent years, several additional foods have emerged as potentially effective. Thus, a detailed update would be valuable, both to caregivers and to individuals seeking to improve their cholesterol levels.

Therefore, researchers of the Dalarna County Council, Norslund-Svärdsjö Academic Primary Health Care Center, Björkvägen, Sweden, analyzed to evaluate the evidence regarding the effects of foods on LDL cholesterol levels and to compare the findings with current guidelines.

They conducted both an umbrella review of guidelines and systematic reviews and a systematic review and meta-analysis of randomized controlled trials (RCTs). The researchers included data from 37 guidelines, 108 systematic reviews, and 20 RCTs. They included patients who were not treated with lipid-lowering medications. The major outcome assessed was LDL cholesterol in mmol/L (conversion factor from mg/dL 0.02586). They evaluated the strength of evidence using The Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

Key findings of the study:

• With high evidence, the researchers found that the foods high in unsaturated and low in saturated and trans-fatty acids (e.g. rapeseed/canola oil), with added plant sterols/stanols, and high in soluble fiber (e.g. oats, barley, and psyllium) caused at least moderate (i.e. 0.20–0.40 mmol/L) reductions in LDL cholesterol.
• They also noted with high evidence that tomatoes, whole flaxseeds, and almonds can reduce LDL cholesterol, whereas boiled/unfiltered coffee can increase it.
• They further observed moderate evidence for beneficial effects by avocados, hazelnuts, and walnuts (high in unsaturated fatty acids), and pulses (high in soluble fiber and plant protein); by turmeric and green tea; and for a small detrimental effect by free sugars.
• They reported that other identified foods were either neutral or had low or very low evidence regarding their effects.

Notably, some foods were not explicitly included in any of these guidelines despite moderate or strong evidence in their favor, e.g. flaxseeds, tomatoes, turmeric, avocados, and green tea.

The authors wrote, "Better biological understanding (including potential adverse effects or drug interactions) could increase the incentive to include novel foods (e.g. tomatoes, turmeric, and green tea) in future dietary recommendations and help identify other relevant foods."

The authors concluded, "Several foods can distinctly modify LDL cholesterol levels. This updated summary of the accumulated evidence may help inform clinicians and future guidelines for dyslipidemia and CVD prevention."

For further information:

DOI: https://doi.org/10.1016/j.numecd.2020.12.032

Keywords: Humans, Food, Diet, LDL cholesterol, Blood lipids, Lipoproteins, GRADE Levels, Nutrition Metabolism & Cardiovascular Diseases.