Historical changes in the mineral content of fruit and vegetables in the UK from 1940 to 2019: a concern for human nutrition and agriculture

Figures & data

Figure 1. Percentage change in mineral nutrient content of fruits and vegetables between 1940 and 2019. **Significant change (p < 0.01); *significant change (p < 0.05).

Table 1. Comparisons of minerals, water, and dry matter content of fruits and vegetables between 1940–1991, 1991–2019 and 1940–2019.

Comparison	Na	K	Ca	Mg	P	Fe	Cu	Water	Dry matter
Period 1, 1940–1991	−32.2%	−6.1%	−5.5%	−23.3%	+9.6%	−22.8%	−60.1%	+0.8%	−5.8%
P-value (paired T-test)	0.025	0.525	0.012	0.000	0.769	0.351	0.005	0.234	0.234
Period 2, 1991–2019	−28.7%	+1.5%	+3.2%	+17.8%	−8.3%	−35.5%	+29.2%	+0.6%	−6.2%
P-value (paired T-test)	0.215	0.156	0.183	0.011	0.523	0.001	0.921	0.070	0.070
Overall period, 1940–2019	−51.7%	−4.7%	−2.5%	−9.7%	+0.5%	−50.2%	−49.1%	+1.4%	−11.6%
P-value (Greenhouse–Geisser)	0.022	0.411	0.078	0.001	0.800	0.001	0.041	0.072	0.072

Table 2. Summary of changes over time in mineral content of horticultural produce reported in the literature (does not include reviews but only includes studies which performed analysis on national data sets).

Author(s)	Country (and time period)	Changes in mineral content found in study			Methods and other key information
		Significant decreases	No significant change	Significant increases
Mayer (1997)	UK (1930s–1980s)	Ca, Mg, Cu, Na in vegetables	Fe, K, P	N/a	Change in mineral content per fresh weight for 20 vegetables^a and 20 fruits, from the 3rd^b and 5th editions of COF. Geometric mean changes from parametric analysis. Changes in moisture content observed
		Mg, Fe, Cu, K in fruits	Ca, Na, P	N/a
Cunningham et al. (2002) ^C	Australia (1980s–2000s)	Fe, Zn	N/a	Mg, Na, K, Ca	Change in mineral content per fresh weight for 44 fruits and vegetables, 1981–1985 to 2000–2001. Moisture levels are reported as similar at the two dates
Davis et al. (2004)	USA (1950s–1990s)	Ca, P, Fe	N/a	N/a	Change in mineral content per dry weight for 39 vegetables and 4 fruits, from 1950 and 1999 USDA tables. Parametric and non-parametric analyses are similar [median changes: Ca −16%, P −9%, Fe −15%]
Ekholm et al. (2007)	Finland (1970s–2000s)	K, Mn, Zn, Cu, Ni (Cd, Al, Pb)^d	Co, Fe, P, Ca, Mg	Se	Directional change in mineral content per dry weight for 1980 versus 2000s. published values (17 vegetables, 7 fruits, 4 grains). No quantitative changes reported
White and Broadley (2005)	UK (1930s–2000s) and USA (1950s–1990s)	Mg, Cu, Na (UK vegetables) K, Fe, Cu (UK fruit) Ca, Fe, Cu (US fruit and vegetables)	K, Ca, Fe, Cl, P (UK vegetables) Ca, Mg, Na, Cl, P (UK fruit) K, Mg, P (US fruit and vegetables)		Change in mineral content per dry weight for 26 UK vegetables and 27–38 UK fruits published between 1929–1944 and 2002, plus 16–50 US foods published in 1941 and 2004. Geometric mean changes from parametric analysis
Davis (2011)	USA (1950s–2009)	Median changes: Ca −12%, P −10%, Fe −43%			Change in mineral content per dry weight for 41 botanical fruits, from 1950 and 2009 USDA tables. Parametric and non-parametric analyses are similar

^aIncludes mushrooms.

^bValues for fruits and vegetables unchanged between 1st and 4th editions.

^cCunningham et al. reported increases and decreases without statistical analysis, we analysed their data using the methods described by Mayer and the values shown in bold were found to be significant.

^dElkholm et al. also reported values for non-essential, potentially toxic elements shown in brackets.

Table 3. Lower Reference Nutrient Intake (LRNI) values in the UK.

	LRNI
Age (years)	K mg/d	Ca mg/d	Mg mg/d	Fe mg/d	Zn mg/d
Children 1.5–3	800	350	85	6.9	5.0
Boys 4–10	1550	500	160	7.4	6.7
Girls 4–10	1550	500	160	7.4	6.7
Boys 11–18	3300	1000	290	11.3	9.2
Girls 11–18	3300	800	290	14.8	8.0
Men 19–64	3500	700	300	8.7	9.5
Women 19–64 (non-pregnant or lactating)	3500	700	270	11.7	7.0
Men 65+	3500	700	300	8.7	9.5
Women 65+	3500	700	270	8.7	7.0

Data taken from Committee on Medical Aspects of Food Policy (1991).

Table 4. Percentage of UK NDNS participants with average daily intakes below the LRNI for mineral nutrients from food sources.

	% below the LRNI
Age (years)	K	Ca	Mg	Fe	Zn
Children 1.5–3	0	0	0	9	5
Boys 4–10	0	1	0	1	4
Girls 4–10	0	1	3	3	13
Boys 11–18	15	12	27	9	17
Girls 11–18	33	19	48	48	22
Men 19–64	11	4	12	1	6
Women 19–64	26	8	11	27	6
Men 65+	9	3	16	2	6
Women 65+	24	8	15	3	3

Taken from Table E (Public Health England, Food Standards Agency et al. 2016), No explanation has been given for the exclusion of Na. LRNI is not available for Cu and P.

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