One avocado a day - minus "bad" lipoproteins?

Current Developments in Nutrition reports new data from a multicenter randomized trial: in adults with abdominal obesity, adding 1 avocado per day for 26 weeks led to a decrease in the concentration of atherogenic LDL particles, measured by an extended lipoprotein panel (NMR lipoprotein notation). This is a subtle but important marker: it is the number of LDL particles (and not just “regular” LDL cholesterol) that is associated with the risk of atherosclerosis.

Background

• Why not just look at LDL cholesterol. The risk of atherosclerosis is more accurately reflected by the number of atherogenic particles (LDL-P) and apoB: with the same LDL-C, a larger number of particles means more cholesterol "carriers" and a higher probability of penetration into the vascular wall. Modern reviews and consensuses are increasingly promoting apoB/LDL-P as more informative risk markers. NMR lipoprotonotyping (NMR) is used to assess them.
• Why avocados may influence particles. Avocados are high in monounsaturated fats (primarily oleic acid) and fiber, plus they contain phytosterols and lutein. This composition supports the idea that replacing saturated fats and refined carbohydrates with avocados may shift the lipoprotein profile toward fewer atherogenic particles.
• What the early “feed” RCTs showed. In a controlled crossover trial (5 weeks on each diet), a “moderate-fat” diet with one avocado per day reduced LDL-P, the proportion of small dense LDL, and LDL-C more than the same diets without avocado. This set the stage for longer, “lifetime” trials.
• What is known from large cohorts. In two long-term US samples, higher regular avocado consumption was associated with lower risk of CVD and CHD; this was particularly true when replacing half a serving of butter/margarine, cheese, eggs or processed meat with an avocado equivalent. That is, the benefit is expected as a substitution effect.
• Why do we need a long-term RCT in free life? Feeding studies show the mechanism, but the real effect is determined by what exactly displaces avocado in the daily diet. That is why the multicenter HAT project is testing long-term outcomes (26 weeks) in people with abdominal obesity: in accompanying publications, the same intervention improved diet quality and lipids, but did not change the integral cardioscore AHA Life's Essential 8 and vascular function indices - an important context for the results on LDL particles.
• What to expect in the clinic and how to interpret it. If daily avocado reduces LDL/apoB, this is a biologically plausible pathway to reducing atherosclerosis, but it remains an intermediate marker; clinical outcomes require longer periods and/or combined diet and lifestyle changes. The key is to replace less favorable calories (sources of saturated fat, “fast” carbohydrates), not to add avocado “on top.”
• Limitations of the field. Some of the avocado work is industry funded; effects may depend on baseline diet, weight, and metabolic status. Therefore, independent replications are important, as well as discordance analysis (where LDL-C is “normal” and apoB/LDL-P is elevated).

What did they do?

The study is part of a larger project called HAT ( Habitual Diet and Avocado Trial ). Participants with abdominal obesity were randomized into two groups for 26 weeks:

• Avocado group: usual diet + 1 avocado daily;
• Control: usual diet with minimal consumption of avocado.

The primary endpoint in the new publication was the concentrations of lipoprotein particles and their subclasses (including LDL particles), which were determined by NMR; this analysis allows one to distinguish, for example, small dense LDL (more atherogenic) from large ones and to estimate the total number of LDL particles.

Results

After 26 weeks, the avocado group had lower atherogenic LDL particle concentrations (as measured by the NMR panel) compared to the control group. This is consistent with earlier controlled feeding trials where avocado reduced total LDL particle counts, small dense LDL, and oxidized LDL levels after just 5 weeks.

How does this compare to other outcomes of the same program?

Parallel publications on HAT have shown that one avocado per day:

• improves diet quality (HEI-2015) and modestly improves lipid profile (reduction in LDL-C and total cholesterol), and is associated with better self-reported sleep;
• does not change the AHA Life's Essential 8 integrated cardiovascular score over 6 months and does not improve vascular function measures (FMD, arterial stiffness) in a separate study.
  This is important context: LDL particles change, but “stiff” vascular function tests do not.

Why "particles" are important

In the clinic, they increasingly look not only at LDL cholesterol, but also at LDL-particle number (LDL-P) or apoB: a higher number of particles for the same LDL-C means more cholesterol “carriers” that more easily penetrate the vessel intima. A decrease in the number of atherogenic particles is a signal in the right direction in terms of the risk of atherosclerosis.

What does it mean "for life"

• Avocado works as a “replacement,” not as an “add-on.” The benefits are expected when avocado displaces less favorable calories (refined carbs/saturated fat sources) and helps pull the diet toward a “Mediterranean” profile: more monounsaturated fats and fiber.
• You shouldn't expect miracles instantly. Vascular function hasn't changed in six months; the effect is metabolic and lipoprotein, not "all at once". This is normal for nutritional interventions "with one meal".

Restrictions

This is a dietary RCT in a free-living population: much depends on what exactly the avocado was displacing in the participant’s particular diet. LDL particle measurements are intermediate markers, not clinical events; also, the HAT was negative for “hard” outcomes (LE8, vascular function). Finally, many of the avocado studies are industry-supported—this requires careful independent replication.

Does this fit into the broader science of avocados?

Yes: Systematic reviews and early controlled “feeding” studies have shown a reduction in LDL-C, an improvement in LDL particle profile, and a reduction in oxidized LDL when avocado is included in a moderate-fat “healthy” diet. The new paper adds evidence over a long time horizon (26 weeks) and specifically for particles.

Source: Damani JJ et al. Effect of Incorporating One Avocado per Day Versus Habitual Diet on Lipoprotein Particle Concentration: A Randomized Controlled Trial, Current Developments in Nutrition, 2025