Study analysis · Nutrients · 2018
Half an avocado at breakfast lowered blood sugar as much as a whole one — and improved blood vessel function by 5 absolute percentage points in a 6-hour lab study.
In 31 overweight adults, adding half or a whole avocado to breakfast lowered peak blood sugar and improved blood vessel function for a few hours, but this short study can't prove long-term health benefits.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study is like a fair test where people were randomly assigned to eat different breakfasts, so we can be fairly confident that the avocado itself changed their short-term blood sugar and blood vessel function. But it only looked at one meal and a few hours afterward, so we can't say that eating avocados regularly prevents heart disease or diabetes.
What’s the bottom line?
Scientists gave 31 overweight adults three breakfasts: no avocado, half avocado, or whole avocado. They checked blood sugar, insulin, blood vessel function, and blood fats for 6 hours after eating.
How strong is this study?
The study was well-designed because it randomly assigned people and compared avocado meals to a control meal, which helps rule out other reasons for the results. However, only 31 people finished, it was very short, and it was paid for by an avocado industry group, so we should be cautious about how much we trust it for long-term health advice.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
71 / 100
- Randomization+20/20
- Blinding+9/15
- Control group+15/15
- Sample size (n=31)+2.9/20
- Follow-up+10/10
100 / 100
46 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registration+15/15
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. The randomized crossover design can support causal inference for acute postprandial effects on glucose, insulin, and FMD within the controlled setting, but it cannot establish long-term effects on disease outcomes. Limitations include small sample (n=31), single-blind design, acute single-meal exposure, and limited generalizability.
COI Unknown
Could not determine conflict of interest status
No conflict of interest or funding statement was included in the provided text; the study's COI status cannot be determined from the available information.
The provided text appears to be truncated before the declarations, funding, or conflict of interest sections. The study tests Hass avocados, and such trials are sometimes industry-funded, but no such statement is present in the analyzed text.
Key takeaways
- 01
With avocado, peak blood sugar was 7.0 mmol/L vs 8.1 mmol/L with no avocado — an absolute drop of 1.1 mmol/L (about 14% lower relative).
- 02
Blood vessel widening doubled from about 5% to 10% — an absolute increase of 5 percentage points (100% relative increase).
- 03
Whole avocado lowered triglyceride-rich lipoproteins (p=0.02) and raised larger HDL particles (p<0.05).
- 04
Ox-LDL, MCP-1, and IL-6 did not change; TNF-alpha tended lower (p=0.07).
- 05
This was a 6-hour lab test in 31 people, not a long-term heart-health trial.
- 06
The absolute differences were: peak blood sugar 1.1 mmol/L lower and blood vessel dilation 5 percentage points higher with avocado.
- 07
The study did not report absolute long-term risk of diabetes or heart disease, so we cannot say avocado prevents those conditions.
Surprising findings
- Half an avocado was as effective as a whole avocado for lowering glucose and insulin peaks and improving FMD.Common intuition says more avocado equals more benefit, but the dose-response was flat for these outcomes.
- Whole avocado increased small LDL particles, a pattern often considered atherogenic, while also increasing larger HDL particles.Avocado is usually framed as uniformly beneficial for blood lipids; this mixed lipoprotein signal complicates the 'superfood' narrative.
- FMD doubled from ~5% to ~10% — a 100% relative increase — but the absolute increase was only 5 percentage points.Relative increases can sound huge, but absolute changes matter more for clinical meaning. A 5-point bump may or may not be clinically important.
- Inflammatory markers Ox-LDL, MCP-1, and IL-6 did not change at all, despite the meals being high-fat/high-carbohydrate challenges.High-fat or high-carb meals are often said to spike inflammation acutely; this study found no differences between avocado and control for these markers.
Practical takeaways
If you're overweight and want to blunt post-meal blood sugar spikes, try replacing some refined breakfast carbs with half an avocado.
This was a single 6-hour meal test in 31 people, not a long-term weight-loss or diabetes-prevention trial. The meals were energy-matched, so this is not a weight-loss strategy.
medium confidenceHalf an avocado may be enough for glucose, insulin, and blood vessel benefits — you don't need a whole one for those outcomes.
Whole avocado was needed for the triglyceride-rich lipoprotein and HDL particle changes, and those effects were mixed.
medium confidenceDon't count on avocado to lower inflammation after a meal; Ox-LDL, MCP-1, and IL-6 were unchanged.
Only acute postprandial markers were measured. Chronic inflammation may respond differently to long-term dietary patterns.
medium confidenceIf you have prediabetes or insulin resistance, discuss with your clinician whether avocado swaps fit your eating plan.
Participants had elevated fasting glucose (5.0–6.4 mmol/L) but not diagnosed diabetes, so results may not apply to everyone.
low confidenceWhy this study matters
Blood sugar peak dropped from 8.1 to 7.0 mmol/L
In this randomized crossover trial, peak postprandial glucose was 7.0 mmol/L with avocado vs 8.1 mmol/L without — an absolute drop of 1.1 mmol/L (about 14% relative lower, p<0.0001). Insulin peaks were also lower (p<0.005), and half an avocado worked as well as a whole one.
People care about blood sugar spikes, especially with insulin resistance or prediabetes. A simple breakfast swap cut the peak below the European Diabetes Policy Group's 7.5 mmol/L arterial-risk threshold.
Blood vessel dilation doubled — but only by 5 absolute percentage points
Flow-mediated dilation (FMD) rose from about 5% to 10% with avocado meals, an absolute increase of 5 percentage points (100% relative increase), while the control meal showed minimal change (p<0.01). The effect appeared at 1 h 20 min and 3 h 20 min after eating.
FMD is a surrogate for endothelial health. A 5-point absolute jump in a few hours sounds impressive, but the long-term meaning is unknown.
Whole avocado changed lipoproteins in a mixed direction
Whole avocado lowered triglyceride-rich lipoproteins (chylomicrons and VLDL) vs control (p=0.02) and raised medium HDL particles (p=0.004) and large HDL particles (p=0.06). But it also increased small LDL particles (p=0.009) and lowered IDL (p=0.004) — a pattern that is not uniformly 'heart-healthy.'
Avocado is often marketed as a simple heart-healthy food, but this study found both favorable and potentially unfavorable lipoprotein changes after one meal.
Inflammation markers mostly unchanged
Oxidized LDL, MCP-1, and IL-6 did not differ between meals (p>0.05). TNF-alpha trended lower after whole avocado vs control (p=0.07), but this was not statistically significant.
Many people eat avocado for anti-inflammatory benefits. This acute study doesn't support a broad anti-inflammatory effect after a single meal.
Race/ethnicity differences in lipoprotein response — but underpowered
The study reported that race/ethnicity influenced lipoprotein subclass responses (p<0.05). Asian participants had lower large HDL and higher small LDL after the whole avocado meal compared with Caucasian and Hispanic participants.
Personalized nutrition is a hot topic. If confirmed, it suggests avocado's effects on cholesterol particles may differ by ancestry.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists gave 31 overweight adults three breakfasts: no avocado, half avocado, or whole avocado. They checked blood sugar, insulin, blood vessel function, and blood fats for 6 hours after eating.
Research results
With avocado, peak blood sugar was 7.0 mmol/L vs 8.1 mmol/L with no avocado — an absolute drop of 1.1 mmol/L (about 14% lower relative). Blood vessel widening doubled from about 5% to 10% — an absolute increase of 5 percentage points (100% relative increase). Whole avocado lowered triglyceride-rich lipoproteins (p=0.02) and raised larger HDL particles (p<0.05). Ox-LDL, MCP-1, and IL-6 did not change; TNF-alpha tended lower (p=0.07).
What this means - more context
This was a 6-hour lab test in 31 people, not a long-term heart-health trial. The absolute differences were: peak blood sugar 1.1 mmol/L lower and blood vessel dilation 5 percentage points higher with avocado. The study did not report absolute long-term risk of diabetes or heart disease, so we cannot say avocado prevents those conditions.
To assess whether replacing carbohydrate energy in breakfast meals with half or whole fresh Hass avocado improves postprandial metabolic and vascular health in overweight/obese adults. No retraction or corrections reported.
In a randomized crossover trial, 31 overweight/obese adults consumed energy-matched breakfasts with 0 g, 68 g, or 136 g fresh Hass avocado. Avocado meals lowered postprandial glucose and insulin peaks vs control (p<0.0001), independent of dose; peak glucose fell from 8.1 to 7.0 mmol/L (absolute 1.1 mmol/L lower; ~14% relative lower). FMD rose from ~5% to ~10% (absolute +5 percentage points; 100% relative increase) with avocado vs minimal control change (p<0.01). Whole avocado lowered TG-rich lipoproteins (p=0.02) and increased larger HDL (p<0.05); Ox-LDL, MCP-1, and IL-6 were unchanged; TNF-alpha trended lower (p=0.07). No retraction or corrections reported.
Methods Used
Single-center, randomized, controlled, 3-arm, 6 h crossover trial; n=31 completers (overweight/obese middle-aged adults, BMI 25–35, 25–60 years). Participants consumed energy-matched breakfast meals containing 0 g (Control), 68 g (Half-A), or 136 g (Whole-A) fresh Hass avocado on 3 occasions. Outcomes included postprandial glucose/insulin, flow-mediated dilation (FMD) at 1 h 20 min and 3 h 20 min, NMR lipoprotein particles, and inflammatory/oxidative markers. Registered NCT02479048.
Main Finding
Replacing breakfast carbohydrate with avocado acutely lowered postprandial glucose peak from 8.1 to 7.0 mmol/L (absolute 1.1 mmol/L lower; ~14% relative lower) and lowered insulin peaks vs control, independent of avocado dose. FMD doubled from ~5% to ~10% (absolute +5 percentage points; 100% relative increase) with avocado vs control (p<0.01). Whole avocado lowered TG-rich lipoproteins (p=0.02) and raised larger HDL particles (p<0.05). Ox-LDL, MCP-1, and IL-6 did not differ; TNF-alpha trended lower (p=0.07). Absolute long-term disease risk was not assessed or reported.
Confidence Level
Moderate. Randomized crossover and pre-registered, but small sample (n=31 completers), acute 6 h single-meal design, no long-term clinical outcomes, no effect sizes or confidence intervals reported, and industry funding from the Hass Avocado Board with an author advisory role. No retraction or corrections reported.
Study Flags
Red Flags
- •Small sample (n=31 completers) and acute single-meal 6-hour design; no long-term clinical outcomes.
- •Industry funding from the Hass Avocado Board and author conflict of interest (Avocado Nutrition Science Advisory).
- •Subgroup race/ethnicity analyses were underpowered; no effect sizes or confidence intervals reported.
Surprising Findings
Half an avocado was as effective as a whole avocado for lowering glucose and insulin peaks and improving FMD.
Common intuition says more avocado equals more benefit, but the dose-response was flat for these outcomes.
Practical Takeaways
If you're overweight and want to blunt post-meal blood sugar spikes, try replacing some refined breakfast carbs with half an avocado.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This study is like a fair test where people were randomly assigned to eat different breakfasts, so we can be fairly confident that the avocado itself changed their short-term blood sugar and blood vessel function. But it only looked at one meal and a few hours afterward, so we can't say that eating avocados regularly prevents heart disease or diabetes.
Strengths
- Randomized controlled crossover design
- Energy-matched control and avocado meals
- Dose-response comparison (half vs whole avocado)
Weaknesses
- Small sample size (31 completers, 20.5% attrition)
- Single-center, single-blind
- Acute postprandial only; cannot assess long-term effects
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists gave 31 overweight adults three breakfasts: no avocado, half avocado, or whole avocado. They checked blood sugar, insulin, blood vessel function, and blood fats for 6 hours after eating.
Research results
With avocado, peak blood sugar was 7.0 mmol/L vs 8.1 mmol/L with no avocado — an absolute drop of 1.1 mmol/L (about 14% lower relative). Blood vessel widening doubled from about 5% to 10% — an absolute increase of 5 percentage points (100% relative increase). Whole avocado lowered triglyceride-rich lipoproteins (p=0.02) and raised larger HDL particles (p<0.05). Ox-LDL, MCP-1, and IL-6 did not change; TNF-alpha tended lower (p=0.07).
What this means - more context
This was a 6-hour lab test in 31 people, not a long-term heart-health trial. The absolute differences were: peak blood sugar 1.1 mmol/L lower and blood vessel dilation 5 percentage points higher with avocado. The study did not report absolute long-term risk of diabetes or heart disease, so we cannot say avocado prevents those conditions.
To assess whether replacing carbohydrate energy in breakfast meals with half or whole fresh Hass avocado improves postprandial metabolic and vascular health in overweight/obese adults. No retraction or corrections reported.
In a randomized crossover trial, 31 overweight/obese adults consumed energy-matched breakfasts with 0 g, 68 g, or 136 g fresh Hass avocado. Avocado meals lowered postprandial glucose and insulin peaks vs control (p<0.0001), independent of dose; peak glucose fell from 8.1 to 7.0 mmol/L (absolute 1.1 mmol/L lower; ~14% relative lower). FMD rose from ~5% to ~10% (absolute +5 percentage points; 100% relative increase) with avocado vs minimal control change (p<0.01). Whole avocado lowered TG-rich lipoproteins (p=0.02) and increased larger HDL (p<0.05); Ox-LDL, MCP-1, and IL-6 were unchanged; TNF-alpha trended lower (p=0.07). No retraction or corrections reported.
Methods Used
Single-center, randomized, controlled, 3-arm, 6 h crossover trial; n=31 completers (overweight/obese middle-aged adults, BMI 25–35, 25–60 years). Participants consumed energy-matched breakfast meals containing 0 g (Control), 68 g (Half-A), or 136 g (Whole-A) fresh Hass avocado on 3 occasions. Outcomes included postprandial glucose/insulin, flow-mediated dilation (FMD) at 1 h 20 min and 3 h 20 min, NMR lipoprotein particles, and inflammatory/oxidative markers. Registered NCT02479048.
Main Finding
Replacing breakfast carbohydrate with avocado acutely lowered postprandial glucose peak from 8.1 to 7.0 mmol/L (absolute 1.1 mmol/L lower; ~14% relative lower) and lowered insulin peaks vs control, independent of avocado dose. FMD doubled from ~5% to ~10% (absolute +5 percentage points; 100% relative increase) with avocado vs control (p<0.01). Whole avocado lowered TG-rich lipoproteins (p=0.02) and raised larger HDL particles (p<0.05). Ox-LDL, MCP-1, and IL-6 did not differ; TNF-alpha trended lower (p=0.07). Absolute long-term disease risk was not assessed or reported.
Confidence Level
Moderate. Randomized crossover and pre-registered, but small sample (n=31 completers), acute 6 h single-meal design, no long-term clinical outcomes, no effect sizes or confidence intervals reported, and industry funding from the Hass Avocado Board with an author advisory role. No retraction or corrections reported.
Study Flags
Red Flags
- •Small sample (n=31 completers) and acute single-meal 6-hour design; no long-term clinical outcomes.
- •Industry funding from the Hass Avocado Board and author conflict of interest (Avocado Nutrition Science Advisory).
- •Subgroup race/ethnicity analyses were underpowered; no effect sizes or confidence intervals reported.
Surprising Findings
Half an avocado was as effective as a whole avocado for lowering glucose and insulin peaks and improving FMD.
Common intuition says more avocado equals more benefit, but the dose-response was flat for these outcomes.
Practical Takeaways
If you're overweight and want to blunt post-meal blood sugar spikes, try replacing some refined breakfast carbs with half an avocado.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Moderate probability
on the GRADE evidence scale
This study is like a fair test where people were randomly assigned to eat different breakfasts, so we can be fairly confident that the avocado itself changed their short-term blood sugar and blood vessel function. But it only looked at one meal and a few hours afterward, so we can't say that eating avocados regularly prevents heart disease or diabetes.
Strengths
- Randomized controlled crossover design
- Energy-matched control and avocado meals
- Dose-response comparison (half vs whole avocado)
Weaknesses
- Small sample size (31 completers, 20.5% attrition)
- Single-center, single-blind
- Acute postprandial only; cannot assess long-term effects
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study was well-designed because it randomly assigned people and compared avocado meals to a control meal, which helps rule out other reasons for the results. However, only 31 people finished, it was very short, and it was paid for by an avocado industry group, so we should be cautious about how much we trust it for long-term health advice.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
71 / 100
- Randomization+20/20
- Blinding+9/15
- Control group+15/15
- Sample size (n=31)+2.9/20
- Follow-up+10/10
100 / 100
46 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registration+15/15
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 564 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design can establish causation. The randomized crossover design can support causal inference for acute postprandial effects on glucose, insulin, and FMD within the controlled setting, but it cannot establish long-term effects on disease outcomes. Limitations include small sample (n=31), single-blind design, acute single-meal exposure, and limited generalizability.
COI Unknown
Could not determine conflict of interest status
No conflict of interest or funding statement was included in the provided text; the study's COI status cannot be determined from the available information.
The provided text appears to be truncated before the declarations, funding, or conflict of interest sections. The study tests Hass avocados, and such trials are sometimes industry-funded, but no such statement is present in the analyzed text.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Thomas DeLauer cite this study, drawing 2 claims from it.
Authored by
3 researchersIf this is your work, this is how we attribute it on Fit Body Science. Eunyoung Park is listed as the lead author.