Food is the primary source of nickel exposure for the general (non-occupational) population. While food nickel poses minimal risk to most adults, children and nickel-sensitized individuals are high-risk groups.
Nickel Content in Foods
Nickel-rich sources (mg Ni/kg) [1]:
| Food | Ni content (mg/kg) |
|---|---|
| Cocoa | 8.2-17.1 |
| Grains, legumes, cereals | 0.3-9.8 |
| Nuts | 0.2-6.7 |
| Soy products | 0.1-5.1 |
| Mushrooms | 1.5-5.0 |
| Oatmeal | 0.77-1.76 |
| Chocolate | ~0.6 |
| Canned vegetables | <0.01-0.52 |
Other sources of dietary nickel contamination:
- Stainless steel cookware (especially with acidic foods like tomato, vinegar, lemon) [2]
- Tap water (first quart from faucet may contain leached nickel from fixtures)
- Canned foods (metal leaching from cans)
- Food processing equipment (industrial nickel contamination)
Regulatory Thresholds
- EFSA TDI: 13 μg/kg body weight/day [1].
- LOAEL: 4.3 μg Ni/kg body weight (critical effect: eczematous flare-up in Ni-sensitized humans).
- Margin of Exposure: recommended ≥30.
- Normal diet provides ~300 μg/day for adults; nickel is not regulated in food in most jurisdictions.
Children as a High-Risk Group
Children are particularly vulnerable [1]:
- Immature detoxification systems
- Higher food intake relative to body weight
- High consumption of nickel-rich foods (chocolate, cocoa, cereals)
- French study: 7.9-37.9% of children (1-36 months) exceeded TDI; up to 98% under upper-bound estimates
- Main sources for children: chocolate/cocoa products, cereals
- Infant formula: soy-based formulas contain more nickel (0.05 mg/kg with iron fortification vs 0.02 without)
Celiac Disease Intersection
A striking connection: gluten-free diets are naturally high in nickel [3]:
- GF staples (corn, chickpeas, lentils, buckwheat) overlap significantly with high-nickel foods
- Celiac patients on strict GFD may develop Ni ACM symptoms due to increased nickel load
- A combined GFD + low-nickel diet resolved symptoms in 83.4% of cases
Low-Nickel Diet
Practical guidance for reducing dietary nickel [2]:
Avoid: whole grains (wheat bran, oatmeal), beans/lentils/peas/soy, all nuts and seeds, chocolate/cocoa, canned foods, black tea, commercial salad dressings, stainless steel cookware for acidic foods.
Reduce absorption:
- Vitamin C with meals (competitive inhibitor of nickel absorption)
- High iron diet (iron competes for absorption)
- Run tap water briefly before use (flush nickel from faucet fixtures)
Target intake for sensitized individuals: 100-150 μg/day may be beneficial [4].
Key Sources
Connections
- nickel allergy — dietary nickel triggers systemic contact dermatitis
- nickel — the metal
- [1] — most comprehensive data on children's exposure
- Relates to metabolic syndrome — dietary nickel as non-occupational exposure route