Walk through any American supermarket, and you will see an abundance our great-grandparents could hardly have imagined. Strawberries in January. Mountains of broccoli, spinach, and sweet peppers every day of the year. By almost any measure, we have solved the problem of producing enough food.
A new report asks a question I believe every health-conscious person should hear: is that food still carrying the nourishment it once did?
The report is called Hollow Harvests: Rebuilding the Nutritional Value of Crops in an Age of Abundant Calories. Deep Science Ventures and The Mark Leonard Trust published it in 2026, and it pulls together six decades of research on the nutrient content of our crops. Its conclusion is sobering. Many of the grains and vegetables we eat today are measurably less nutrient-dense than the same foods were before the 1960s, and several forces now in motion could make the problem worse.
One note in fairness before we begin. Deep Science Ventures is a firm that builds new companies, and the later chapters of the report scope out business opportunities in soil health. That does not weaken the science it reviews, which rests on peer-reviewed studies I have listed at the end of this article, but it is worth knowing who wrote it. In what follows, I will walk you through what the report found, where its evidence is strong and where it is still preliminary, and what you can do about it at your own table.
Hidden Hunger: Full Plates, Missing Nutrients
Researchers call this problem hidden hunger. It describes a person who eats enough calories, sometimes far too many, yet still falls short on the vitamins and minerals the body needs to function well.
The numbers are larger than most people realize. More than 2 billion people worldwide have at least one clinical micronutrient deficiency, most often iron, iodine, zinc, vitamin A, folate, or calcium. A 2024 modeling study in The Lancet Global Health estimated that more than 5 billion people take in too little iodine, vitamin E, and calcium, and more than 4 billion fall short on iron, riboflavin, folate, and vitamin C. A 2022 pooled analysis found that over half of preschool-aged children and two-thirds of non-pregnant women of reproductive age worldwide have at least one micronutrient deficiency. Altogether, hidden hunger accounts for an estimated 7% of the global burden of disease.
You might assume this is mainly a problem in poorer countries, but wealthy nations have their own version. Here it shows up less as classic deficiency diseases like rickets or goiter and more as people who are well fed yet quietly undernourished. In the United States, the CDC has reported deficiency rates above 10% for vitamin B6, vitamin D, and iron in the general population, and vitamin D deficiency reaches 31% among non-Hispanic Black Americans. Our own Dietary Guidelines list vitamin D, calcium, potassium, and fiber as nutrients of public health concern because so many Americans fall short. In the United Kingdom, 83% of women of childbearing age had red blood cell folate below the level targeted to reduce the risk of neural tube defects.
The effects of these shortfalls are often subtle. Mild deficiencies can sap energy, dull concentration, weaken immune defenses, and reduce your resilience long before a lab test flags a disease. That subtlety is exactly why the problem stays hidden.
The Evidence That Our Crops Have Changed
The report’s core is a review of what has happened to the nutrient content of crops since the Green Revolution of the 1960s, when high-yielding varieties, synthetic fertilizers, and pesticides transformed farming. That revolution was a genuine triumph, and the report honors it. Cereal yields rose 215% per hectare while farmland expanded only 15%, and the share of people undernourished in developing nations fell from 35% to 12%. The report’s concern is what may have been quietly traded away in the process.
Three independent lines of evidence point in the same direction.
The first comes from comparing official food composition tables over time. A widely cited 2004 study compared USDA data for 43 garden crops between 1950 and 1999. After adjusting for moisture, it found reliable declines in 6 of 13 nutrients, including protein (down 6%), calcium (16%), phosphorus (9%), iron (15%), and riboflavin (38%). A 2022 British study extended the UK tables from 1940 to 2019 and found that, across fruits and vegetables combined, iron fell by 50.2%, copper by 49.1%, sodium by 51.7%, and magnesium by 9.7%.
Critics have long pointed out that these comparisons are imperfect. Varieties, growing regions, sampling methods, and laboratory techniques all changed over the decades. That is a fair objection, which is why the second line of evidence matters.
Controlled side-by-side studies remove most of those variables. When researchers grew 14 varieties of hard red winter wheat, released over many decades, together in the same field, every nutrient measured showed the same pattern: the higher the yield, the lower the concentration. Newer varieties carried less iron, zinc, and selenium, with each falling by roughly a third of a percent for every year of breeding progress. In 27 commercial broccoli hybrids grown side by side, higher yields went hand in hand with lower calcium and magnesium. Because these plants shared the same soil, weather, and care, the differences come from the plants themselves.
The third line of evidence is, to my mind, the most persuasive. Rothamsted Research in England is home to the Broadbalk wheat experiment, which has been running since the 1840s. Researchers analyzed archived grain stretching back 160 years. Zinc, iron, copper, and magnesium in the grain held steady from 1845 until the mid-1960s, then dropped after shorter, high-yielding varieties were introduced. Compared with the older varieties, modern wheat grown in 2000-2005 had 33-49% less zinc, 25-39% less copper, 23-27% less iron, and 20-27% less magnesium. At the same time, phytate, a compound that blocks the absorption of iron and zinc, rose relative to those minerals.
Here is the detail that stopped me. The archived soil samples showed no decline in minerals; they were stable or even increasing. The soil had not run out. The plants had changed.
A 2026 global analysis in Nature Food confirmed the pattern, finding that zinc, iron, and protein have all declined in wheat varieties released since the 1960s, and that fewer than one-third of bread wheat varieties released in that period meet the zinc target of 38 mg/kg. Similar shifts appear in corn, where 80 years of breeding nudged protein down and starch up. A small sample of UK supermarket vegetables by the University of Lincoln this year averaged 40% lower nutrient density than the reference tables used for food labels, though the authors caution that the sample was too small to be conclusive.
Why Bigger Harvests Can Mean Thinner Nutrition
Scientists call this the dilution effect. When a plant is bred or fertilized to grow bigger and faster, it can build starch and bulk more quickly than it can draw minerals from the soil and move them into the grain or fruit we eat. The harvest grows, but the nutrients inside it are spread more thinly.
One fertilizer study in red raspberries shows how dramatic this can be. Adding phosphorus increased the plants’ total dry matter by 37% at one level and 119% at a higher level. Phosphorus in the plant rose about 20%, as you would expect, but the concentrations of the other eight minerals measured fell by 20-55%. The modern short-stemmed wheat varieties that powered the Green Revolution were developed to send more of the plant’s resources into the grain, and they did exactly that for starch and yield. The minerals did not keep pace.
The report puts the stakes plainly. If a food loses 40% of its nutrient density, you would need to eat about 67% more calories to get the same nourishment. For most of us, eating two-thirds more food is neither possible nor healthy.
Then comes processing. Some traditional methods, such as fermentation, soaking, and sprouting, actually make nutrients easier to absorb. Others, like refining grain into white flour, strip away the bran and germ where many minerals live. Ultra-processed foods are estimated to have, on average, 80% less nutrient density than unprocessed whole foods, and they now supply more than half of the calories in several high-income countries, including 56.8% of total energy intake in the UK. In a study of Portuguese adults, those who ate the most ultra-processed food had up to 50% higher rates of specific micronutrient shortfalls than those who ate the least.
The report pictures nutrition as a pipeline running from the soil, through the plant, the harvest, the factory, and your plate, and finally into your own gut and cells. Nutrients can be added or lost at every stage. Most public health advice focuses on the last few steps: what we buy, how it is processed, and what we choose to eat. The report’s central point is that the very first steps, where nutrition is grown into our food, have been largely overlooked.
How Extra Calories Hid the Problem
If our food has been losing nutrients for 60 years, why haven’t deficiencies exploded? The report offers an uncomfortable answer: we have been making up the difference by eating more.
According to the Food and Agriculture Organization, the average global dietary energy supply rose from 2,185 calories per person per day in 1961 to 3,006 in 2023, an increase of 38%. In middle- and upper-income countries, it now exceeds 3,300. Over roughly the same span, worldwide obesity more than doubled between 1990 and 2022. Year-round access to fresh produce and more affordable animal foods helped too, but much of the cushion appears to have come from sheer volume. Studies consistently show that total calorie intake is one of the strongest predictors of whether people meet their micronutrient needs.
In other words, many of us have been treading water nutritionally while eating more food than our grandparents did. That is an inefficient and costly trade. Extra calories carry their own burden of weight gain, insulin resistance, and the chronic diseases that follow, which is why we now see people who are overweight and micronutrient-deficient at the same time. The answer is not more food. It is more nourishment in every bite.
Pressures on the Horizon
The report identifies several forces that could push crop nutrition further downhill in the coming decades.
The best studied is rising carbon dioxide. Higher CO2 levels can boost plant growth, but the extra growth is mostly carbohydrate, and protein and mineral concentrations in the edible parts fall. The Intergovernmental Panel on Climate Change has stated with high confidence that elevated CO2 lowers crop nutritional quality. One modeling study estimated that by 2050 this effect alone could leave an additional 175 million people zinc deficient and 122 million more protein deficient. Rice grown under mid-century CO2 levels has been shown to lose 17-30% of some B vitamins, which researchers estimate could add 132 million disability-adjusted life years of folate-deficiency burden worldwide.
The second pressure is the soil itself. About one-third of the world’s soils are now considered moderately to highly degraded through erosion, loss of organic matter, salt buildup, compaction, and contamination. Nearly half of the soils used to grow cereals may have zinc levels low enough to limit crops. Erosion is projected to rise sharply as the climate changes, and 66% of croplands are projected to lose soil selenium by 2080. Degraded soils also respond poorly to fertilizer, so even well-intentioned farmers may struggle to grow nutrient-dense food.
The third pressure is economic. Farmers are paid for volume, grade, and shelf life, not for the vitamins and minerals in their harvest. Nutrient density is invisible at the point of sale, so there is little reward for protecting it. The report offers one telling exception. Bread-making wheat must meet a 13% protein threshold to be sold for that purpose, and once breeding hit that floor, protein decline stopped. When the market asks for nutrition, it gets it. For nearly everything else, it hasn’t asked.
GLP-1 Medications: Eating Less Without Eating Better
The newest pressure is one many of my readers know personally. GLP-1 medications such as semaglutide and tirzepatide have moved from diabetes care into mainstream weight management at remarkable speed. The share of American adults using GLP-1 injectables more than doubled in a single year, from 5.8% in 2024 to 12.4% in 2025.
These medications work largely by quieting appetite, and they work well. Studies of dietary intake show calorie reductions of 16-39%. In the landmark STEP 1 trial, semaglutide produced an average weight loss of 14.9% over 68 weeks, compared with 2.4% on placebo. Even after weight stabilizes, calorie intake is estimated to stay about 16% below where it started. For people burdened by obesity, that is a real gift.
Here is the catch the report raises. If the extra calories of the past 60 years have been masking declining nutrient density, then a sudden, large drop in how much we eat removes the mask. GLP-1 users do tend to make some better choices, eating out at fast-food restaurants less often and shifting toward foods lower in sugar and saturated fat. The problem is that smaller portions of the same diet still deliver smaller amounts of every nutrient.
Early data bear this out. A 2025 cross-sectional study of 69 American adults taking GLP-1 medications, using three-day food records, found that 98.6% fell below the recommended intake for potassium and vitamin D, 94% for choline, 90% for magnesium, and 88% for iron. These findings are preliminary. The sample was small, the study was funded by a supplement retailer, and many participants likely had less-than-ideal diets before starting treatment. Still, the pattern makes biological sense: less food means fewer nutrients unless the diet is deliberately rebuilt around nutrient density.
The report’s authors modeled what this could mean for British adults aged 19-64, using the country’s national diet survey. If 15% of adults take a GLP-1 medication and eat 20% fewer calories, they estimate that at least 1 in 6 users would be pushed below the minimum intake level for at least one nutrient, more than 1 million people. When they combined that 15% adoption rate with a 15% decline in crop nutrient density, a scenario they consider highly plausible, roughly 5 million working-age adults became vulnerable to at least one deficiency. Potassium and selenium, which come largely from plant foods, were especially sensitive to falling crop nutrient density. These are scenarios rather than forecasts, but they show how quickly two seemingly unrelated trends could combine.
The Good News: Nutrition Can Be Grown Back In
The most hopeful part of the report is that none of this is inevitable. The same research that documents the decline also shows enormous variation in the field today, and variation means room for improvement. Testing thousands of crop samples, the Bionutrient Institute found that protein and minerals can vary more than twofold within a single crop species, and that antioxidant compounds in vegetables can vary by as much as 200-fold. Two carrots that look identical on the shelf may be very different foods.
What drives that difference? The report points to three factors working together: the plant’s genetics, how it is farmed, and the soil and climate it grows in. Each can be improved. A global meta-analysis of field trials found that fertilization raised crop yields by 30.9% and nutritional quality by 11.9% on average, with potassium, magnesium, and micronutrient fertilizers all helping. In wheat, adding zinc and iron alongside standard fertilizer raised grain zinc by 27%, iron by 41%, and protein by 25%. Varieties bred specifically for higher mineral content carried 18.5% more zinc and 20% more iron, and applying zinc to both the soil and the leaves raised grain zinc by an average of 65%.
Soil health appears to matter a great deal. In paired comparisons of neighboring farms growing the same crops, fields with healthier soil produced food with on average 34% more vitamin K, 15% more vitamin E, 15% more carotenoids, 20% more phenolics, 22% more phytosterols, and 27% more copper. The study was small, but it fits a consistent picture. Fertilizer also works better in healthy soil, with the strongest nutritional responses seen where soil organic matter sits around 2.5-5%. The report makes an important point: arguing over “organic versus conventional” misses the real question, which is whether a farming system builds the living soil plants need to gather nutrients.
The report’s modeling suggests that raising crop nutrient density by roughly 30-40% would be transformative. In the UK, it would offset the nutritional impact of widespread GLP-1 use. Across low- and lower-middle-income countries, an average 30% increase in crop zinc would halve zinc deficiency for some 455 million people, without anyone having to change what they eat. There is precedent, too. Finland has added selenium to its fertilizers since the 1980s to raise the selenium content of its food supply.
I find something deeply fitting in this. One of the first tasks given to humanity was to tend and keep the garden (Genesis 2:15). The health of the soil and the health of the people it feeds were never meant to be separate concerns. Caring well for the ground beneath our crops is, in a very practical sense, caring for ourselves and our neighbors.
What This Means at Your Table
You cannot fix national farm policy from your kitchen, but you can make choices that work with this research rather than against it.
First, make every calorie count. If our food carries less nutrition per bite than it once did, then empty calories cost you more than ever. Build your meals around whole, minimally processed plant foods: vegetables, legumes, fruits, nuts, seeds, and intact whole grains. Choose whole grains over refined ones, since milling removes much of the mineral content. This is the same low-glycemic, whole-food, plant-forward pattern I recommend for cancer prevention and metabolic health, and the report gives one more reason it matters.
Second, widen your variety. Just three crops (wheat, rice, and corn) supply about 60% of the world’s calories, and a diet built on a narrow set of staples inherits all of their weaknesses. Rotating through many different vegetables, beans, and grains spreads your risk and broadens the range of nutrients and protective plant compounds you take in.
Third, prepare food in ways that unlock its nutrients. Soaking, sprouting, and fermenting grains and legumes reduce phytate and make minerals such as iron and zinc easier to absorb. Traditional cooks understood this long before science explained it.
Fourth, learn where your food comes from. When you can, buy from growers who invest in their soil through cover crops, compost, reduced tillage, and careful nutrient management. Ask them about it at the farmers’ market. Based on the evidence in this report, how the soil is cared for may tell you more about a vegetable’s nutritional value than its label.
Fifth, if you take a GLP-1 medication, plan your meals carefully. With a smaller appetite, there is simply less room for foods that do not pull their weight. Put vegetables, legumes, and quality protein first, and work with your physician to monitor your nutrient status as your intake changes.
Finally, test rather than guess. Hidden hunger is hidden precisely because it rarely announces itself. A thoughtful blood panel can reveal shortfalls in iron, vitamin D, folate, vitamin B12, magnesium, zinc, and other nutrients before they cause harm. This is especially important for anyone living with cancer or another chronic illness. Our bodies have a protective hormone called hepcidin, which raises iron absorption when stores run low and holds it back when stores are full. Chronic inflammation, however, pushes hepcidin up and can leave a person functionally short of iron even when their diet and stores look adequate. Ferritin, the usual marker of iron stores, also rises with inflammation, so it can look reassuring when it should not.
That is also why I caution against guessing with supplements. More is not always better. In randomized trials in Kenyan infants, iron fortification shifted the gut microbiome toward harmful bacteria and increased intestinal inflammation, because much of the iron went unabsorbed. Supplements work best when they are matched to a measured need.
A Harvest Worth Restoring
The Hollow Harvests report asks us to rethink what food security means. For 60 years we have measured success in tons and calories, and by that measure we have done extraordinarily well. The report argues that the better measure is nutrition delivered per acre, per calorie, and per person, and by that measure we have work to do.
Some of the evidence is still emerging. The size of the decline varies from crop to crop and nutrient to nutrient; the UK projections are scenarios rather than predictions, and the GLP-1 nutrition data are early. But three independent lines of research agree on the direction: as we bred and fertilized crops for ever-higher yields, many became less nourishing, and extra calories have quietly covered the gap.
The encouraging news is that the tools to reverse this already exist in better crop breeding, smarter fertilization, and, above all, healthier soil. Until those changes reach the grocery store, the most reliable protection is a varied, whole-food diet and a clear picture of what is actually happening inside your own body.
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