Silicon is a crucial trace mineral that plays a vital role in the health of both humans and plants, often overlooked due to its ubiquitous nature. In humans, it is essential for the synthesis of collagen and connective tissues, benefiting bones, skin, hair, and nails. For plants, it strengthens cell walls, improves resistance to environmental stresses, and enhances nutrient uptake. When this element is lacking in a bioavailable form, a deficiency can develop, leading to negative consequences.
What causes silicon deficiency in humans?
For humans, the causes of silicon deficiency are typically related to a combination of dietary intake, absorption issues, and age-related changes. It is not necessarily the scarcity of the element in the environment but rather its availability and how the body processes it.
Dietary intake
A primary cause is simply a diet that is insufficient in silicon-rich foods. Modern, highly processed diets often strip away the very parts of plants that contain this beneficial mineral.
- Low intake of plant-based foods: Diets that are low in whole grains, fruits, and vegetables are typically deficient in silicon. Foods like oats, barley, green beans, and leafy greens are excellent sources.
- High fiber consumption (controversial): Some studies have suggested that high fiber diets may reduce the gastrointestinal absorption of certain minerals, including silicon, though this effect is still under review.
Poor absorption
Even when consuming a diet with decent silicon content, the body's ability to absorb it can be compromised by several factors. Silicon from food sources must first be metabolized into a form the body can use, such as orthosilicic acid.
- Reduced stomach acidity: With advancing age or certain illnesses, the production of gastric acid can decrease. This lower acidity diminishes the body's ability to effectively metabolize and absorb silicon from dietary sources.
- Mineral competition: High dietary intake of other minerals can interfere with silicon absorption. Research suggests that calcium and magnesium can compete for the same absorption pathways or form insoluble silicates in the gut, reducing silicon's bioavailability.
Age-related factors
As the body ages, its capacity to maintain healthy silicon levels naturally declines. This is a gradual process that can begin in early adulthood and manifest more noticeably later in life.
- Decreasing body stores: The concentration of silicon in the body's connective tissues, like bones and arteries, decreases with age.
- Overall intake reduction: Some research suggests that overall silicon intake tends to decrease in elderly individuals.
What causes silicon deficiency in plants and soil?
In agriculture, silicon deficiency is often a direct result of environmental conditions and unsustainable farming practices that deplete the soil of this vital nutrient. Unlike humans, plants depend entirely on the soil to provide bioavailable silicon, typically absorbed as monosilicic acid.
Soil depletion
- Intensive cultivation: Long-term, intensive farming, especially of silicon-accumulating crops like rice and sugarcane, systematically removes silicon from the soil without adequate replenishment.
- Highly weathered and leached soils: In humid climates, especially in tropical areas, extensive weathering and leaching can cause a significant loss of soluble silicon from the soil, leaving behind insoluble forms that are unavailable to plants.
Soil type and composition
- Organic soils (Histosols): Soils composed almost entirely of humus and organic matter are inherently low in mineral content, including silicon. This is a common issue in greenhouse production using peat-based soilless mixes.
Agricultural practices
- Lack of residue recycling: The practice of removing crop straw and husks from fields after harvest, rather than returning them to the soil, is a major cause of silicon loss over time. Recycling these materials is a key strategy for replenishment.
- NPK fertilizer reliance: Over-reliance on synthetic nitrogen, phosphorus, and potassium (NPK) fertilizers, without considering silicon replenishment, can contribute to soil nutrient imbalances and depletion.
Plant-specific factors
- Genetic predisposition: Not all plants are equal in their ability to accumulate silicon. Some species are naturally better at absorbing it than others. Dicot plants, for example, are generally considered non-accumulators and may not take up sufficient silicon even when it's present in the soil.
The absorption problem: A comparison of humans vs. plants
| Feature | Humans | Plants |
|---|---|---|
| Form Absorbed | Orthosilicic acid (from dietary silicates) | Monosilicic acid (from soil solution) |
| Primary Cause of Deficiency | Poor dietary intake and inefficient gastrointestinal absorption | Low availability in soil due to depletion or weathering |
| Key Absorption Factor | Stomach acid level, competition with other minerals | Soil pH, water content, microbial activity |
| Bioavailability Issue | Highly polymerized silicon in some foods is poorly absorbed (e.g., bananas) | Soil's total silicon content can be high, but the bioavailable fraction is often low |
| Age Factor | Absorption and tissue concentration decline with age | Not applicable; depends on current soil conditions |
| Remediation | Balanced diet, supplements (if necessary), addressing underlying health issues | Soil amendments, residue recycling, appropriate fertilizers |
Conclusion: Addressing the root causes
Understanding what causes silicon deficiency is the first step toward prevention and management for both human and agricultural health. For individuals, this means focusing on a balanced diet rich in whole foods and being mindful of age-related changes and potential absorption issues. For farmers and agricultural professionals, it involves sustainable soil management, including the recycling of crop residues and the use of silicon-containing fertilizers to replenish depleted soil reserves. By addressing these core causes, the benefits of this vital trace mineral can be maximized, leading to stronger plants and healthier people.
For additional information on the role of silicon in human health, you can refer to the National Institutes of Health PMC article.
