For many (but not all) microbiome conditions, trace mineral supplementation helps. This is a review of the current literature on PubMed.
- “No significant differences in the whole blood Cu, Zn/Cu ratio, Fe, or Mg was detected between the ASD group and the control group.” [2019 Study]
- It is notable that whole blood Fe level in boys with ASD was significantly higher than in girls with ASD, and was nearly significant when compared with the control level of boys.
- After stratification for age, a significant 6% decrease in whole blood Zn levels was detected in preschool-aged children with ASD as compared to the control values.
- The results of the present study suggest an association between whole blood levels of Zn in Chinese children with ASD.
- Concentrations of lead, arsenic, copper, zinc, mercury, calcium and magnesium were significantly higher in the ASD group than in the control group. [2019 Study]
- No differences in intracellular Mg were found between controls and pathological subjects; however, autistic children and children with other autistic spectrum disorders had significantly lower plasma concentrations of Mg than normal subjects (p=0.013 and p=0.02, respectively) [2006 Study]
- “The Vitamin D and folate levels of children with ASD were significantly lower than those of control children. The levels of calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) in children with ASD were significantly lower than those in control children, and no significant difference was found in copper (Cu) levels. Correlation analysis showed that Vitamin A and Ca levels were negatively correlated with ASD symptoms. Folate, Ca, Fe and Zn were positively correlated with the Gesell Developmental Scale GDS scores of autistic children. ” [2018 Study]
- Autistic children with high MBP-Ab levels were characterized by 28% higher serum Mn and lower Mg concentration. [2018 Study]
- ” hair concentrations of chromium (p=0.024), cobalt (p=0.012), iodine (p=0.000), iron (p=0.017), and magnesium (p=0.007) in ASD patients were significantly lower than those of control subjects, while there were higher magnesium levels in the hair of ASD patients compared to that of controls (p=0.010). Patients with ASD had higher blood levels of copper (p=0.000) and lower levels of zinc compared to controls (p=0.021). Further urinary iodine levels in patients with ASD were decreased in comparison with controls (p=0.026). ” [2017 Study]
- This study suggests that deficiency of iron and Vitamin D as well as anemia were more common in autistic compared to control children. [2017 Study]
- Is high prevalence of Vitamin D deficiency evidence for autism disorder?: In a highly endogamous population. 
- These results indicate that lower 25(OH) D levels may be independently associated with severity of ASD among Chinese patients, and lower serum 25(OH) D levels could be considered as an independent risk factor for ASD. [2014 study]
- Assessment of infantile mineral imbalances in autism spectrum disorders (ASDs).  applies to 0-3 only
- ASD children also had significantly higher levels of essential minerals sulfur, sodium, magnesium, potassium, zinc, and iron, but lower levels of calcium and copper in their hair samples. This study corroborates data from previous studies in different parts of the world indicating the presence of elevated levels of heavy metals and selective depletion of essential minerals in the hair of children with ASD. [2013 Study]
- There was a significant positive correlation between lead & verbal communication (p = 0.020) and general impression (p = 0.008). In addition, there was a significant negative correlation between zinc & fear and nervousness (p = 0.022). [2012 Study]
- “a case of a 9-year-old boy with autism that responded positively to nutritional supplements. a combination of a large dose of vitamin B6 (pyridoxal HCl) and magnesium. ” [2011 Study] this was for one person
- Vitamin B6-magnesium treatment for autism: the current status of the research.
- this study suggests that the behavioral improvement observed with the combination vitamin B6-magnesium in PDD/autism is associated with concomitant modifications of Erc-Mg values. [2006 Study]
- his small study (n=8) only measured IQ and ‘Social Quotient’ and found a statistically significant benefit for IQ (5.2, 95% CI = [0.2 to 10.3]) when in the treated group, by using change scores. ue to the small number of studies, the methodological quality of studies, and small sample sizes… no recommendation can be advanced regarding the use of B6-Mg as a treatment for autism. [2005 Study]
- Brief report: lack of response in an autistic population to a low dose clinical trial of pyridoxine plus magnesium. 
Magnesium and Vitamin B6 trials reported positive results on some subgroups with sufficient dosage. Vitamin D supplementation until the child is close to the top of the normal range appears likely to have significant effect. Zinc is reported high is some studies and low in other studies. For a child with fear and nervousness, supplementation may reduce the severity.
The available weak evidence is low iodine levels. Magnesium was lower except that it was higher in hair samples. This suggests that ASD metabolism may influence what is found in the hair.