2018NEJM
Estruch et al. (PREDIMED)
7,447 adults at high heart risk
A Mediterranean diet with extra olive oil or nuts cut heart attacks, strokes and heart deaths by about 30% compared with a low-fat diet.
Find on PubMed ↗Research library · Food & life
Food and fibre: what's on your plate
Poor diet is linked to more deaths worldwide than smoking. No single superfood matters as much as the overall pattern: mostly plants, whole grains, beans, nuts, olive oil and fish, with little ultra-processed food.
Strong evidence−30%heart attacks, strokes and heart deaths on a Mediterranean diet with olive oil or nutsPREDIMED 2018, NEJM, 7,447 people
−15–30%death risk for people eating the most fibre vs the leastReynolds 2019, Lancet, 185 studies + 58 trials
11Mdeaths worldwide in one year linked to poor diet, more than any other riskGBD 2017 Diet Collaborators, Lancet 2019
01
The basics
What a healthy pattern looks like
The diets with the strongest evidence, like the Mediterranean and DASH diets, share the same base: lots of vegetables, fruit, beans and lentils, whole grains, nuts and seeds, olive oil and fish, with modest dairy and little red or processed meat and sugar.
Fibre is a common thread. It feeds the trillions of bacteria in your gut, which turn it into short-chain fatty acids that calm inflammation, support the gut lining and help regulate blood sugar and appetite. Most people eat under 20 g a day; benefits peak around 25–30 g or more.
Ultra-processed foods (packaged snacks, sugary cereals, soft drinks, processed meats, ready meals) are engineered to be easy to overeat. They now make up more than half of the calories in many Western diets.
Build a healthy plate
Based on the Harvard Healthy Eating Plate: half vegetables and fruit, a quarter protein, a quarter whole grains, healthy oils and water to drink.
02
How it works
How fibre works for you
1
You eat plants
Vegetables, fruit, beans, whole grains, nuts and seeds deliver fibre.
2
Gut bacteria feed
Fibre passes to the large intestine, where microbes ferment it.
3
Helpful compounds
Bacteria make short-chain fatty acids like butyrate.
4
Whole-body benefits
Less inflammation, steadier blood sugar, lower cholesterol and better fullness.
03
Measure it
How to check your diet
- Count plants: aim for 30 different plant foods a week (vegetables, fruits, beans, grains, nuts, seeds, herbs and spices all count). People who hit this had more diverse gut bacteria in the American Gut Project.
- Estimate fibre: a cup of beans has about 12–15 g, a pear 6 g, a bowl of oats 4 g, a slice of wholemeal bread 2–3 g.
- Check labels: a long list of ingredients you wouldn't find in a kitchen is a sign of ultra-processing.
Try your number
LowBelow targetOn targetHigh
545
Benefits in Reynolds 2019 peaked at 25–29 g and kept rising above that. Increase slowly to avoid bloating.
04
What the research says
The key studies
2019Lancet
Reynolds et al.
185 studies + 58 trials
People eating the most fibre had 15–30% lower death and heart disease risk, and less stroke, type 2 diabetes and bowel cancer. Whole grains showed similar benefits.
Find on PubMed ↗2019Cell Metabolism
Hall et al.
20 adults, controlled trial
On an ultra-processed diet, people ate about 500 calories a day more and gained weight in 2 weeks, even though meals were matched for sugar, fat and fibre.
Find on PubMed ↗2019Lancet
GBD 2017 Diet Collaborators
195 countries
Poor diet was linked to 11 million deaths in 2017. Too much salt, too few whole grains and too little fruit were the top problems.
Find on PubMed ↗1999Circulation
de Lorgeril et al. (Lyon Diet Heart)
605 heart attack survivors
A Mediterranean-style diet cut repeat heart attacks and heart deaths by about 50–70% over 4 years.
Find on PubMed ↗2021Cell
Wastyk et al.
36 adults
Eating more fermented foods (yoghurt, kefir, kimchi) for 10 weeks increased gut microbe diversity and lowered 19 markers of inflammation.
Find on PubMed ↗05
Take action
Simple swaps that add up
Add good things first. It's easier than banning foods.
- 1
Half your plate plants
Vegetables, salad, fruit or beans at every meal.
- 2
Beans or lentils most days
The cheapest, easiest fibre and protein boost.
- 3
Whole grains
Oats, brown rice, wholemeal bread, barley and quinoa instead of white versions.
- 4
Olive oil and nuts
Cook with extra-virgin olive oil; a handful of nuts a day.
- 5
Fish twice a week
Especially oily fish like salmon, sardines and mackerel.
- 6
Fermented foods
Yoghurt, kefir, sauerkraut or kimchi a few times a week.
- 7
Cut the ultra-processed
Fewer packaged snacks, processed meats and sugary drinks. Cook simple meals more often.
06
Myth or fact
Common myths, checked
✕ MythCarbs are bad.
✓ FactRefined carbs and sugar are the issue. Whole grains, beans and fruit are linked to longer life.
✕ MythSupplements can replace a good diet.
✓ FactTrials of single vitamins mostly failed. Whole foods work as a package.
✕ MythAll fat is unhealthy.
✓ FactOlive oil, nuts and oily fish are among the healthiest foods studied.
✕ MythOrganic or 'natural' means healthy.
✓ FactOrganic crisps are still crisps. The food type matters more than the label.
07
Questions
Frequently asked
Do I need to go vegetarian?
No. Mediterranean diets include fish, some dairy and small amounts of meat. Eating more plants is what matters.
How do I add fibre without bloating?
Add a few grams a week, drink enough water and give your gut bacteria time to adjust.
Is red meat harmful?
Processed meat (bacon, ham, salami) is most clearly linked to bowel cancer and heart disease. Unprocessed red meat a few times a week is less of a concern.
08
Sources
References and related topics
- Estruch et al. (PREDIMED) (2018). NEJM. 7,447 adults at high heart risk. PubMed ↗
- Reynolds et al. (2019). Lancet. 185 studies + 58 trials. PubMed ↗
- Hall et al. (2019). Cell Metabolism. 20 adults, controlled trial. PubMed ↗
- GBD 2017 Diet Collaborators (2019). Lancet. 195 countries. PubMed ↗
- de Lorgeril et al. (Lyon Diet Heart) (1999). Circulation. 605 heart attack survivors. PubMed ↗
- Wastyk et al. (2021). Cell. 36 adults. PubMed ↗