As parents get ready to send their kids back to school, here are supplements to consider for shoring up young ones’ immune systems to protect against colds, flu and ­COVID-19. Not all kids need them, but depending on diet, sun exposure and ­antibiotic use, they may make sense. Doses here are for kids ages two to 12.

Vitamin D. We naturally produce vitamin D when our skin is exposed to sunlight, but about 10% of kids are deficient and another 60% have suboptimal levels. It’s best to get D through sun exposure—and gain the benefits of fresh air and exercise. Kids who spend less than 10 to 15 minutes outdoors daily or don’t drink D–fortified milk may need supplements.

Important: Ask your doctor to test your child’s vitamin D levels, which should be about 50 ng/mL. If they are low, try ­supplementing with 1,000 international units (IU) to 2,000 IU of D-3 daily. Buy flavored liquid drops and give them with a meal. Retest after three months, then follow your doctor’s advice on further supplementation. 

Probiotics. These great-for-you bacteria live in your gut and, among other jobs, help regulate the immune system. In children, use of antibiotics and a high-sugar diet are common reasons that make it difficult for healthy gut bacteria to flourish. The strains Lactobacillus acidophilus and Bifidobacterium may help reduce incidence of colds and flu in children. Aim for three to five servings a week of fermented foods such as kefir, yogurt, kimchi, ­sauerkraut and miso soup. Supplements are an effective alternative for picky eaters. 

Flavored powders or liquids are easily mixed into water, juice or food. Give five to 10 billion colony-forming units (CFUs) daily or per label instructions at the end of a meal. Probiotics also are helpful when your child is taking an antibiotic. Take a double dose at least two hours away from the medicine, then a regular daily dose for an additional month. Important: If your child has compromised immunity, check with your doctor about whether probiotics are safe for him/her to take.

Echinacea. This herb can help kids heal faster from a cold, flu, ­viral sore throat or ear infection. Choose a flavored children’s tincture. Follow label instructions. If a family member is sick with a virus, giving your child echinacea for a week or two can boost his immunity to keep him from getting sick, too. Caution: If your child has allergies, especially to ragweed, mums, marigolds or daisies, ask your doctor if it is safe to use.

Note: There’s been a lot about zinc ­defending against COVID-19 in adults. For children, unless a blood test shows zinc deficiency, I just recommend a children’s multivitamin, which contains zinc.