Scientists wanted to know if a special diet designed to help both people and the planet actually gives you all the vitamins and minerals your body needs. They looked at what over 9,600 people in the UK ate and checked their blood work. The good news: people who followed this “planetary health diet” more closely got better nutrition, especially for iron, zinc, calcium, and vitamin D. The diet worked about as well as the Mediterranean diet (which doctors often recommend). However, there was one nutrient—vitamin B12—that didn’t improve with this diet, so people following it would need to pay attention to that one.

The Quick Take

  • What they studied: Whether a diet designed to be good for both human health and the environment actually provides all the nutrients people need to stay healthy
  • Who participated: Over 9,600 people living in the United Kingdom, ages 15 and older, who kept detailed food diaries for 4 days. About half of them also had blood tests to check their nutrient levels.
  • Key finding: People who followed the planetary health diet more closely were significantly more likely to get enough iron (2.4 times more likely), zinc (1.3 times more likely), calcium (1.8 times more likely), and vitamin D (3.4 times more likely) compared to those who followed it less closely.
  • What it means for you: If you’re thinking about switching to a diet that’s better for the environment, this research suggests you can do so without worrying about missing important nutrients—except you’ll want to make sure you’re getting enough vitamin B12, possibly through supplements or fortified foods.

The Research Details

Researchers used information from a large, ongoing UK government survey that tracks what people eat. They looked at food diaries from over 9,600 people collected between 2008 and 2019. For each person, they calculated a “planetary health diet score” based on how much of 14 different food groups they ate (like whole grains, legumes, nuts, fish, and vegetables). The score ranged from 0 to 140 points, with higher scores meaning the person’s diet was more aligned with the planetary health diet recommendations.

They then compared people with higher scores to those with lower scores to see if the higher-scoring people had better nutrition. They also looked at blood test results from about 4,600 of these people to measure actual nutrient levels in their bodies. The researchers adjusted their analysis to account for things like age, income, exercise habits, and body weight that might affect nutrition.

This approach is important because it uses real-world eating data from a representative sample of the UK population, not just a small group of volunteers. By checking both what people reported eating and their actual blood nutrient levels, the researchers could confirm whether the diet actually delivers the nutrients it promises. This gives us confidence that the findings apply to regular people, not just those in a controlled lab setting.

This study has several strengths: it included a large number of people from across the UK, used government survey data that’s carefully collected, and verified findings with blood tests. However, because it’s a snapshot in time (cross-sectional), we can’t prove that the diet caused better nutrition—only that people eating this way tend to have better nutrition. The study also relied on people’s memories of what they ate, which can sometimes be inaccurate. Additionally, the findings are specific to the UK population and may not apply equally to other countries with different food availability.

What the Results Show

The study found that the average person in the UK scored 75.8 out of 140 points on the planetary health diet scale, meaning most people weren’t fully following the diet. However, those who did follow it more closely had much better nutrition across the board.

For iron, people who scored 20 points higher on the planetary health diet scale were 2.4 times more likely to get enough iron. For zinc, the improvement was smaller but still meaningful (1.26 times more likely). Calcium showed a strong improvement (1.81 times more likely), and vitamin D showed the biggest improvement (3.35 times more likely).

When researchers looked at blood test results, they found the same pattern: higher planetary health diet scores were linked to better nutrient levels in the blood for most vitamins and minerals tested. This is important because it proves the diet actually delivers what it promises, not just on paper but in people’s bodies.

Interestingly, vitamin B12 was the exception. There was no clear connection between following the planetary health diet and having adequate B12 levels. This makes sense because B12 comes mainly from animal products like meat, fish, and dairy, and the planetary health diet recommends eating less of these foods.

The positive effects of the planetary health diet held true across different age groups and for both men and women. When researchers compared the planetary health diet to the Mediterranean diet (a well-known healthy diet), both diets showed similar benefits for most nutrients. This suggests that the planetary health diet is just as nutritionally adequate as other diets that doctors recommend, while also being better for the environment.

Previous research has raised concerns about whether environmentally-friendly diets can meet all human nutritional needs. This study addresses those concerns by showing that the planetary health diet can indeed provide adequate nutrition for most nutrients. The findings align with other research showing that plant-based diets can be nutritionally complete when properly planned. However, the B12 finding confirms what nutritionists have long known: anyone eating less animal products needs to pay special attention to B12 intake.

The study only looked at UK residents, so results may not apply to other countries with different foods available or different eating patterns. Because people reported what they ate from memory, there may be some inaccuracy in the dietary data. The study shows associations (things that go together) but can’t prove that eating this way causes better nutrition—only that people who eat this way tend to have better nutrition. Finally, the study didn’t look at long-term health outcomes, so we don’t know yet if better nutrition from this diet leads to better health over time.

The Bottom Line

If you’re interested in eating in a way that’s better for the environment, this research suggests you can do so without compromising your nutrition. Focus on eating more whole grains, legumes (beans and lentils), nuts, seeds, and vegetables while eating less red meat and processed foods. Make sure to include good sources of vitamin B12, such as fortified plant-based milks, nutritional yeast, or supplements. This recommendation has moderate-to-strong evidence support from this study.

This research is relevant for anyone considering a more plant-based or environmentally-conscious diet, particularly those concerned about whether they’ll get enough nutrients. It’s especially useful for people who want to reduce their environmental impact without sacrificing health. People with specific nutrient deficiencies or those taking certain medications should consult a doctor or registered dietitian before making major dietary changes. Pregnant women, children, and people with certain health conditions should also get personalized advice.

If you switch to eating more like the planetary health diet, you might notice some changes in how you feel within a few weeks as your body adjusts. However, improvements in nutrient levels (as measured by blood tests) typically take several weeks to months to become apparent, depending on which nutrients you’re focusing on. Long-term health benefits would take months to years to fully develop.

Want to Apply This Research?

  • Track your consumption of the 14 food groups in the planetary health diet (whole grains, refined grains, vegetables, fruits, legumes, nuts, seeds, fish, eggs, dairy, red meat, processed meat, sugar-sweetened beverages, and unsaturated oils). Aim to increase scores in plant-based categories while reducing animal products, with a goal of reaching a score of 100+ out of 140.
  • Start by adding one new plant-based food to your diet each week—for example, try lentil soup on Monday, add nuts to your salad on Wednesday, and experiment with a tofu stir-fry on Friday. Use the app to log these additions and track your planetary health diet score as it increases. Set a reminder to include a vitamin B12 source daily (fortified plant milk, nutritional yeast, or a supplement).
  • Use the app to track your planetary health diet score weekly and aim for gradual improvement. Every 4-6 weeks, reflect on how you feel and note any changes in energy levels or digestion. If possible, work with a healthcare provider to check nutrient levels (especially B12) through blood tests every 6-12 months to ensure your diet is meeting your nutritional needs.

This research suggests the planetary health diet can be nutritionally adequate for most people in the UK population, but individual nutritional needs vary. Before making significant dietary changes, especially if you have existing health conditions, take medications, are pregnant, breastfeeding, or have a history of nutrient deficiencies, consult with a registered dietitian or your healthcare provider. This study does not replace personalized medical advice. Pay particular attention to vitamin B12 intake if following this diet, as the research shows this nutrient requires special consideration. If you experience any symptoms of nutrient deficiency (such as fatigue, weakness, or unusual bruising), seek medical attention promptly.