Is silica intake harmful to health?

From the Guidelines

Silica in food is generally not bad for you, as it is a naturally occurring mineral found in many foods and is considered safe for consumption in these natural forms. The human body actually needs small amounts of silica for healthy bones, skin, hair, and nails. However, there is a difference between naturally occurring food silica and synthetic silica additives (like silicon dioxide or E551) used as anti-caking agents in some processed foods. These food-grade additives are regulated and considered safe in the amounts typically used in food products.

Key Points to Consider

• Silica is a naturally occurring mineral found in many foods like whole grains, vegetables, and fruits, and is considered safe for consumption in these natural forms 1.
• The human body needs small amounts of silica for healthy bones, skin, hair, and nails.
• Synthetic silica additives (like silicon dioxide or E551) used as anti-caking agents in some processed foods are regulated and considered safe in the amounts typically used in food products.
• If you have concerns about silica additives in processed foods, you can focus on eating whole, unprocessed foods which contain natural silica that's beneficial to your body.
• There's no need to specifically avoid silica in your diet unless you have a rare specific medical condition that your doctor has advised requires silica restriction.

Important Considerations

It's worth noting that while silica in food is generally safe, exposure to crystalline silica in occupational settings is a known lung carcinogen 1. However, this is not relevant to silica consumption in food.

Recommendations

Based on the available evidence, there is no need to avoid silica in your diet unless you have a specific medical condition that requires silica restriction. Instead, focus on eating a balanced diet with plenty of whole, unprocessed foods that contain natural silica.

From the Research

Silica in Food

• Silica is found in various foods, with higher levels in plant-based foods than animal-based foods 2.
• Foods rich in silica include grains such as oats, barley, and some rice fractions 2.
• The average daily intake of silica is estimated to be around 20-50 mg/day, with higher values for plant-based diets 2.

Health Benefits of Silica

• Silica is considered essential for health, although no recommended daily intake (RDI) has been established 3.
• Deficiency in silica can lead to deformities in skull and peripheral bones, poorly formed joints, and reduced cartilage and collagen content 3.
• Silica has been shown to beneficial for bone health, with potential benefits for joints and connective tissue 3.

Safety of Silica Consumption

• Studies have shown that oral intake of silica is safe and well-tolerated in humans, with no major adverse events or safety concerns 4.
• The No Observed Adverse Effects Level (NOAEL) for dietary silica is estimated to be 50,000 ppm (mg/L) 3.
• However, inhalation of crystalline silica has been linked to various health problems, including silicosis, lung cancer, and kidney disease 5, 6.

Risks Associated with Silica Exposure

• Exposure to silica has been linked to an increased risk of silicosis, lung cancer, and kidney disease 5.
• The current standard for silica exposure in the US is considered insufficient to protect workers' health, with estimated excess risks of 1.9% for silicosis, 1.7% for lung cancer, and 5.1% for end-stage renal disease 5.
• Clinicians should be aware of the risks associated with silica exposure and provide guidance for patients who may be exposed to silica in their work or daily lives 6.