Eating nuts might help to improve cholesterol levels

Nuts and seeds feature almost daily in my diet and are certainly a food that I regularly recommend.  I wrote a piece specifically about almonds a few years ago and since then evidence has continued to accumulate for the health benefits of these foods.  Recently (1) an analysis of published research has found that nuts seem to improve blood lipid (fat) levels.

The report (1) analysed data from 25 trials and found that consuming more nuts seems to be associated with improvements in blood cholesterol levels.  The authors note that: “Recently, consumption of nuts has been the focus of intense research because of their potential to reduce coronary heart disease risk and to lower blood lipid [fat and cholesterol] levels based on their unique nutritional attributes.”   Lowering blood cholesterol concentrations and triglyceride levels has become a cornerstone in preventing coronary heart disease as well as becoming part of the treatment plan process.

The data from the 25 trials (1) came from seven countries and involved over 550 women and men with high or normal cholesterol levels.  All of the studies compared a group who were asked to consume nuts to a control group who were not consuming nuts.  None of the participants in the studies were taking cholesterol lowering medications.  The individuals consuming nuts had an average of 67g daily.  Eating nuts was associated with an average 5.1 % reduction in total cholesterol concentration, a 7.4% reduction in low-density lipoprotein (LDL, or “bad” cholesterol) and an 8.3 % change in ratio of LDL cholesterol to high-density lipoprotein (HDL, or “good” cholesterol).  In addition to this, those who consumed nuts and had high triglyceride (blood fat) levels at the start of the trial experienced a 10.2% decline in triglycerides.  The authors note that the lipid-lowering effects of nut consumption were greatest amongst the individuals who what the highest baseline LDL-C levels and those who were consuming less healthy ‘western’ diets (high in saturated fats and refined carbohydrates) as well as those who were not overweight.

The authors say that different types of nuts had similar effects on blood lipid levels and conclude that (1)Nuts are a whole food that have been consumed by humans throughout history. Increasing the consumption of nuts as part of an otherwise prudent diet can be expected to favorably affect blood lipid levels (at least in the short term) and have the potential to lower coronary heart disease risk.”

Numerous studies suggest that people who regularly consume nuts (around 30g per day) are slimmer than those who do not.  A review (2) stated  “There are claims that energy-dense foods are especially problematic for weight loss and maintenance. Nuts are among the most energy-dense foods consumed, yet the literature consistently documents little impact of their ingestion on body weight”  Nuts seem to satisfy the appetite, they make us feel full and may therefore prevent us overeating on other, less nutritious foods.  This could be due to the fact that, as well as healthy fats, nuts also contain protein and release their energy very slowly into the bloodstream. Evidence also suggests that not all of the fat in nuts is absorbed into the body, much of it being passed out in the stool. 

Nuts are packed with minerals, vitamins, fibre, protein and healthy fats.  The fat in nuts is mainly monounsaturated fat, the same as olive oil, which appears to reduce risk of heart disease.  Nuts are also rich in vitamin E, magnesium, potassium and fibre – all of these nutrients are great for heart health.  Brazil nuts are also very high in selenium which is linked to a reduced risk of cancer and walnuts contain omega 3 fatty acids which have many health properties.  Nuts are energy dense so consuming vast quantities is not necessary, replacing a less healthfull snack, such as a bag of crisps or a sugary cereal/chocolate bar, with a small portion of nuts 30-50g may be a good way to improve the quality of the daily diet.

(1) Sabaté J et al.  2010.  Nut Consumption and Blood Lipid Levels.  A Pooled Analysis of 25 Intervention Trials .  Arch Intern Med. 2010;170(9):821-827.

(2)Mattes RD et al.  2008.  Impact of peanuts and tree nuts on body weight and healthy weight loss in adults. J Nutr 2008;138:1741S-1745S

Written by Ani Kowal