cadmium (Cd) enters the human body primarily through food. Unlike nickel, which has high-concentration food categories that can be avoided, cadmium contamination is diffuse — embedded in staple crops, leafy greens, and grains that form the basis of most dietary patterns worldwide.
How Cadmium Enters the Food Supply
Cadmium reaches food through three primary routes:
Soil contamination. Phosphate fertilizers are the largest anthropogenic cadmium source in agricultural soils. Sewage sludge application, industrial emissions, and atmospheric deposition also contribute. Once in soil, cadmium has a half-life measured in decades — it accumulates over successive growing seasons balali mood 2021 toxic mechanisms five heavy metals.
Plant uptake. Cadmium enters plants through the same calcium (Ca²⁺) and zinc (Zn²⁺) transporters that absorb essential minerals. This is a key example of mis metallation — toxic metals hijacking essential metal channels. Plants cannot distinguish cadmium from calcium at the transporter level, so cadmium-contaminated soil produces cadmium-contaminated crops regardless of species pendergrass 2026 age window vulnerability vegetable baby foods.
Bioconcentration. Certain plant families actively concentrate cadmium above soil levels (bioconcentration factor >1.0). Leafy greens and root vegetables are particularly efficient cadmium accumulators.
Cadmium Content in Foods
The major dietary cadmium sources, ranked by contribution to total intake:
| Food Category | Cd Content Range | Notes |
|---|---|---|
| Rice | 0.01-0.40 mg/kg | Highest single-food contributor globally; paddy flooding mobilizes soil Cd |
| Leafy greens (spinach, lettuce) | 0.01-0.25 mg/kg | Hyperaccumulator crops; organic ≠ lower Cd |
| Root vegetables (carrots, potatoes) | 0.01-0.10 mg/kg | Direct soil contact increases uptake |
| Wheat and cereals | 0.01-0.08 mg/kg | Staple crop, high consumption volume |
| Chocolate/cocoa | 0.01-0.30 mg/kg | Cacao trees accumulate Cd from volcanic soils (Latin America) |
| Shellfish (oysters, mussels) | 0.05-2.0 mg/kg | Filter-feeders concentrate waterborne Cd |
| Organ meats (kidney, liver) | 0.05-1.0 mg/kg | Bioaccumulation in animal excretory organs |
| Sunflower seeds | 0.02-0.20 mg/kg | Sunflowers are known Cd hyperaccumulators |
Critical detail: Rice is the dominant global cadmium source not because it has the highest concentration per kilogram, but because of its enormous consumption volume. In Asian diets, rice can contribute 40-60% of total dietary cadmium balali mood 2021 toxic mechanisms five heavy metals.
Absorption and the Role of Nutritional Status
Cadmium absorption from the GI tract is typically 3-8% in adults, but this increases dramatically under specific conditions:
- Iron deficiency increases cadmium absorption 2-3x via upregulated DMT1 (divalent metal transporter 1) — the same transporter handles both Fe²⁺ and Cd²⁺. This is another mis metallation pathway.
- Calcium deficiency increases Cd absorption through shared calcium channels.
- Zinc deficiency reduces metallothionein production, decreasing the body's cadmium-binding capacity.
- Low protein intake reduces metallothionein synthesis.
This creates a vulnerability paradox: populations with the worst nutritional status absorb the most cadmium from identical dietary exposure.
Infant Vulnerability
Infants face disproportionate cadmium exposure through two mechanisms hopfner 2025 infant formula dietary exposure elements germany:
Formula and baby foods. German infant formula analysis found cadmium contributed up to 178% of the Tolerable Weekly Intake (TWI) in highly exposed infants. Vegetable-based baby foods (carrots, spinach, sweet potatoes) are among the highest-cadmium commercial infant food products.
Immature detoxification. Infants have lower metallothionein expression, immature renal clearance, and higher gut absorption rates. The developmental window from 6-24 months — when solid foods are introduced — coincides with maximum vulnerability to cadmium accumulation pendergrass 2026 age window vulnerability vegetable baby foods.
Cadmium, Diet, and the Gut Microbiome
Dietary cadmium exposure alters gut microbial composition in ways that compound its toxicity:
- High-fat diets amplify cadmium accumulation — mice on HFD showed increased Cd retention in liver and kidney compared to normal diet controls, with corresponding dysbiotic shifts liu 2020 high fat diet heavy metal gut microbiota.
- Cadmium depletes glutathione — the primary intracellular antioxidant and cadmium detoxification molecule. Chronic low-level exposure progressively exhausts glutathione reserves.
- Cadmium and arsenic co-exposure (common in rice-based diets) produces synergistic gut microbiota disruption and liver toxicity beyond what either metal causes alone zhang 2015 arsenic cadmium microbiota liver toxicity mice.
Regulatory Landscape
- EFSA TWI: 2.5 μg/kg body weight/week
- JECFA PTMI: 25 μg/kg body weight/month
- Codex Alimentarius: Maximum levels set for rice (0.4 mg/kg), wheat (0.2 mg/kg), leafy vegetables (0.2 mg/kg), cocoa products (variable by category)
- No FDA action level for cadmium in infant foods (as of 2026)
Key Sources
Connections
- cadmium — the metal entity page
- mis metallation — cadmium enters through calcium and zinc channels
- glutathione — primary cadmium detoxification molecule, depleted by chronic exposure
- heavy metals infant foods — cadmium in baby food and formula
- dietary nickel exposure — parallel dietary metal exposure pathway
- plant metal hyperaccumulation — why certain crops concentrate cadmium
- oxidative stress — cadmium-driven ROS generation via Fenton chemistry