Tractor plowing field

Declining nutrient levels in our soil

Nutrient levels in UK soil have plummeted over the years, meaning our fruits and vegetables are lacking in minerals too. How can you stop the gap?

We know that eating a diet rich in fresh fruits and vegetables is one of the best ways to guarantee we’re getting all the essential nutrients we need to stay healthy. But if the food we eat is lacking vital vitamins and minerals, our diet is at a disadvantage.

Handpicked content: How to get the most nutrients from your food

Have nutrients in our food declined?

The simple answer is yes. A famous long-range study into the nutritional content of food in the UK by McCance and Widdowson found that the mineral levels in fruit, vegetables, milk and meat have all declined significantly over the past 70 years.1 Experts believe modern farming methods and new plant varieties could be to blame.

Overall, magnesium in vegetables has dropped by 24%, while carrots specifically have lost 75% of this essential nutrient – you’d need to eat four carrots today to get the same amount of magnesium found in one carrot in 1940. Spinach has lost 53% of its potassium and 60% of its iron, while broccoli has lost 75% of its calcium.

Nutrient levels in fruit have also declined. These days, you would need to eat three apples or oranges to get the same iron content as from one in 1940, while ten fruits analysed for zinc – including cherries, peaches and strawberries – showed an overall loss of 27%.

Handpicked content: The health benefits of carrots and how to sneak them into your diet

What is stealing nutrients from our food?

David Thomas, a mineralogist, fellow of the Geological Society, and nutritional therapist regularly analyses the data on declining nutrient levels in UK food. He says that the ‘character, growing method, preparation [and] source’ of our food is causing a decline in soil nutrient levels.2 In other words, farming practices and crop varieties are leading to reduced nutrient levels in our fruits and vegetables. His theory is supported by a number of experts. A report published in the British Food Journal in 1997 by Anne-Marie Mayer, a nutrition researcher at Cornell University, stated that farming chemicals and techniques affect the structure, chemistry and ecology of the soil in ways that affect the availability of minerals to plants, and in turn the mineral content of crops.3 The UK is not alone. A landmark study by the University of Texas in 2004 found that there were ‘reliable declines’ in protein, calcium, vitamin C, vitamin B2 and iron in 43 different US fruits and vegetables from 1950 to 1999.4 The study concluded that the decline in nutrient values was due to agricultural practices designed to improve traits including size, growth rate and pest resistance. This is called the ‘dilution effect’: growing crops for greater yield or disease resistance depletes the minerals in soil faster than they can be replenished. However, simply replacing lost nutrients with fertilizer could cause a mineral imbalance within the soil,5 while not leaving fields fallow to ‘recover’ in a bid to boost production can also lead to low mineral levels.

What else could be to blame?

Today we tend to eat food grown around the world, rather than local, seasonal produce. While this means we have a steady supply of fresh fruit and veggies, the way they are stored and transported may lead to a further decline in nutrient levels.6 In 2003, Spanish researchers discovered that broccoli kept in supermarket conditions lost 70% of a protective compound called glucosalinate and 60% of its antioxidant flavonoids over 10 days.7 The type of foods we like to eat has also changed over the years. A study discussed in New Scientist in 2015 revealed that food producers are creating new breeds of fruit and veg to taste less bitter, such as sweet, pink grapefruit.8 The trouble is, the compounds that give plants their bitter taste are often the ones that also have the most protective properties for our health. All this means we should be eating more than our 5-a-day to ensure we get enough vitamins and minerals. But when you consider only 25% of us are hitting this target, we’re simply not getting all the nutrients we need from our food.9

Handpicked content: How to keep the vitamins and minerals in your 'free from' diet

5 ways to up your nutrient intake

Experts agree we should continue to eat a wide range of fresh fruits and vegetables – they are still beneficial for our health – but there are a few ways to make sure you’re getting enough vitamins and minerals:

1. Switch to organic fruit and veg

The largest-ever review of studies into the differences between organic and conventional crops by Newcastle University in 2014 concluded that organic crops were up to 60% higher in a number of key antioxidants.10 The team also found that organic crops had lower levels of pesticide residues including toxic heavy metals.

2. Go for organic meat and dairy

Another study on organic meat and milk reported in the British Journal of Nutrition in 2016 found they contain around 50% more omega-3 fatty acids.11 This most likely due to the animals eating organic grasses and grains that are rich in omega-3s, which then end up in milk and meat products.

3. Stick to seasonal produce
If you can eat local and/or seasonal fruit and vegetables, they won’t have travelled as far and so should still contain healthy nutrient levels.

4. Don’t forget about frozen
Freezing fruits and vegetables almost as soon as they are picked helps preserve their nutrient content. Adding some frozen veg to a casserole or berries to a smoothie can help increase your vitamin and mineral intake.

5. Take a multivitamin and mineral supplement
Plug any gaps by taking a full-spectrum multivitamin. The long-range nutrient study found that sodium, potassium, magnesium, calcium, iron and copper were all significantly lacking in our fruit and vegetables, so any supplement should include these essential minerals.

Advice is for information only and should not replace medical care. Please consult a doctor or healthcare professional before trying any remedies.
Shop our Vitamins & Supplements range.

Sources

1. McCance RA, Widdowson EM. The Mineral Depletion Of Foods Available To Us As a Nation (1940–2002) – A Review of the 6th Edition of McCance and Widdowson. Available from: http://www.mineralresourcesint.co.uk/pdf/Mineral_Depletion_of_Foods_1940_2002.pdf
2. Thomas D. The mineral depletion of foods available to us as a nation (1940-2002) a review of the 6th edition of McCance and Widdowson. Available from: https://www.ncbi.nlm.nih.gov/pubmed/18309763
3. Mayer AM. Historical changes in the mineral content of fruits and vegetables. Available from: http://www.academia.edu/7017054/Historical_changes_in_the_mineral_content_of_fruits_and_vegetables
4. Davis D. Declining Fruit and Vegetable Nutrient Composition: What Is the Evidence? Available from: http://hortsci.ashspublications.org/content/44/1/15.full
5. Jarrell WM, Beverly RB. The dilution effect in plant nutrient studies. Available from: www.researchgate.net/publication/279436494_The_Dilution_Effect_in_Plant_Nutrient_Studies
6. Jones, RB. Effects of postharvest handling conditions and cooking on anthocyanin, lycopene, and glucosinolate content and bioavailability in fruits and vegetables. Available from: http://www.tandfonline.com/doi/pdf/10.1080/01140670709510188
7. Vallejo F, Tomas-Barberan F, Garcia-Viguera C. Health-promoting compounds in broccoli as influenced by refrigerated transport and retail sale period. Available from: www.ncbi.nlm.nih.gov/pubmed/12720387
8. Marta Zaraska. Bitter truth: How we’re making fruit and veg less healthy. Available from: www.newscientist.com/article/mg22730322-100-bitter-truth-how-were-making-fruit-and-veg-less-healthy/
9. Henry Bodkin. Just one in four adults eating their five a day. Available from: http://www.telegraph.co.uk/news/2017/03/30/just-one-four-adults-eating-five-day-nhs-reveals/
10. Baranski M. et al. Higher antioxidant concentrations and less cadmium and pesticide residues in organically-grown crops: a systematic literature review and meta-analyses. Available from: http://www.ncl.ac.uk/press/news/2015/10/organicvsnon-organicfood/
11. Baranski M. et al. PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26878105

Nutrition