Effect of Three Silicon Based Food Supplements on the Urinary Excretion of Aluminum and Other Metals (SILIAL)

Aluminum is a very abundant element in nature. Humans are exposed to this metal through the environment, diet, and drinking water, as well as through the consumption of certain medications.

Aluminum is not an essential element for human, being able to become neurotoxic when it reaches the brain once ingested at very high doses and, above all, if there is also kidney dysfunction.

Silicon is one of the most abundant elements on the planet and although it is not considered an essential element for humans, some beneficial activities have been documented.

Silicon has been found to be readily available in food and that 41% of ingested silicon is excreted in the urine, with a significant correlation between silicon ingested with food and urinary silicon excretion.

The most bioavailable silicon is that found in the form of silicic acid or orthosilicic acid.

Numerous studies suggest that silicon can reduce the oral absorption of aluminum and / or improve its excretion and, therefore, protect against the adverse effects induced by the ingestion of aluminum.

In a clinical study with healthy individuals as a control group for Alzheimer's disease, the levels of aluminum excretion were analyzed after the continuous ingestion of water enriched in silicon. The results in the first urine of the morning during the first week of ingestion of the enriched water showed that the excretion of aluminum was 136.9 ± 81.4 µmol / nmol creatinine while in the baseline week it was lower, 98.8 ± 64.3 nmol / nmol creatinine. These results indicated that the Al excreted came from Al stored in the body.

The main objective of the study is to evaluate the effect of the consumption of three food supplements formulated with different silicon compounds (monomethylsilanetriol and / or silicic acid) on the urinary excretion of aluminum.

The secondary objectives of the study are to evaluate:

* the bioavailability of the silicon contained in three food supplements formulated with different silicon compounds.
* the effect of the consumption of three food supplements formulated with different silicon compounds on urinary excretion of mercury, nickel, arsenic, cadmium, iron and copper.
* the safety of the consumption of three food supplements formulated with different silicon compounds.

It will be conducted a single-center, randomized, controlled, double-blind clinical trial with four groups in parallel (placebo, Supplement A, Supplement B and Supplement C).

The study will be carried out with a total of 40 individuals (10 individuals per group), men and women aged 40 to 65 years. Individuals will have normal serum creatinine levels: up to 1.1mg/dl in women and up to 1.4mg/dl in men.

The investigational products involved in this study are four food supplements made from silicon compounds and the corresponding placebos.

Each participant will receive a kit containing a bottle with 10 capsules and a bottle of 100 ml of liquid according to the treatments corresponding to the randomly assigned group.

During the study, the volunteers will consume one capsule and 100ml of product each day for 7 days. The first morning urine will be collected during the 7 days of treatment and also during the previous 7 days to analyze the baseline values. In addition, on days 6 and 7 of the study, the urine will be collected in three fractions up to 24h to evaluate the bioavailability of silicon.

Participants will make a total of 5 visits, including the pre-selection visit. In these visits, the following will be carried out: Revision of Inclusion and exclusion criteria; Informed consent signature;Safety biochemistry; Demographic variables (age, sex), anthropometric variables; Evaluation of dietary intake; Randomization; Delivery of the sampling material; Verification of compliance with dietary requirements; Collection of urine samples; Investigation product delivery; Determination of metals in urine; Registration of Medication and food supplements; concomitants adverse event registry.

Eligibility Criteria:
Inclusion Criteria:

* Men and women aged 40 to 65.
* Individuals with normal serum creatinine levels: up to 1.1 mg/dl in women and up to 1.4 mg/dl in men.

Exclusion Criteria:

* Individuals taking any type of medication and/or supplement containing aluminum, including antacids.
* Individuals who take food supplements and/or medication that contains mercury, nickel, arsenic, cadmium, iron, copper, and silicon.
* Individuals who eat mineral-enriched foods.
* Individuals allergic to any component of the dietary supplements of the study.
* Individuals with urge, stress or mixed urinary incontinence. Involuntary loss of urine accompanied by symptoms of both urge or stress urinary incontinence diagnosed by your primary care physician. In case of absence of diagnosis, the IU-4 questionnaire will be carried out.
* Pregnancy or breastfeeding.
* Individuals with any chronic gastrointestinal disease.
* Individuals with chronic kidney disease (or serum creatinine levels ≥ 1.7 mg/dl in men and ≥ 1.5 mg/dl in women).
* Be participating or have participated in a clinical trial or study of nutritional intervention in the last 30 days before study inclusion.
* Being a smoker.
* Consume 2 or more Standard Beverage Units daily or 17 weekly in women, or consume 4 or more Standard Beverage Units daily or 28 weekly in mens.
* Individuals whose condition does not allow them to carry out the study procedures strictly.
* Individuals with diseases with manifest symptoms that may influence the objectives of the study.
* Individuals with BMI≥ 30 kg/m\^2.
* Individuals whose consumption of foods rich in silicon, aluminum, mercury, nickel, arsenic, cadmium, iron and copper are high.