01Top picks on our shelves
- High-potency multi-strain formulas (up to 100 billion CFU) — for people who want maximum CFU per capsule in a raw, whole-food-based formula.
- Balanced everyday probiotics — diverse strain profiles aimed at general digestive support; a solid daily driver.
- Shelf-stable probiotic pearls — tiny coated pearls that don't need refrigeration; a good travel or beginner pick.
- Women's formulas — probiotics with strains selected for women's digestive and vaginal health.
- Kid-friendly chewables — lower-dose probiotics in chewable form for families.
02Probiotic FAQ
Do probiotics need to be refrigerated?
Some do, some don't. Traditional refrigerated formulas keep live cultures potent with cold storage, while shelf-stable options use protective coatings or freeze-dried strains. Check the label — and at William's, the refrigerated case and the shelf-stable aisle are both stocked, so ask staff if you're unsure.
What does CFU mean?
CFU stands for "colony-forming units" — the number of live, viable bacteria per serving. Products on our shelves range from 1 billion to 100 billion CFU. Higher isn't automatically better; strain diversity and your personal tolerance matter more than the raw number.
How long does it take for probiotics to work?
Most people give a new probiotic 2–4 weeks of consistent daily use before judging results. The gut microbiome shifts gradually, not overnight. If you notice bloating in the first few days, that's common as your gut adjusts — but persistent discomfort is worth discussing with a healthcare provider.
Should I take probiotics with antibiotics?
This is one of the most common questions we hear. Antibiotics can disrupt gut bacteria alongside the harmful ones, which is why many people take a probiotic during or after a course. Timing matters (usually a few hours apart), so check with your doctor or pharmacist for guidance specific to your prescription.
Are gummies as effective as capsules?
Gummies tend to have lower CFU counts and shorter shelf stability than capsules, but they're far easier to take consistently — and consistency matters most. For kids or anyone who dislikes swallowing pills, a gummy you'll actually take beats a capsule you won't.
What's the difference between probiotics and prebiotics?
Probiotics are the live beneficial bacteria themselves; prebiotics are the fibers that feed them. Many formulas now include both. Eating prebiotic-rich foods (bananas, oats, garlic, onions) alongside your probiotic is a simple way to support the whole system.
03By the numbers
Your gut is home to an estimated 38 trillion microorganisms — roughly as many bacterial cells as you have human cells, according to a widely cited 2016 analysis published in the journal *Cell* (Sender, Fuchs & Milo). The International Scientific Association for Probiotics and Prebiotics (ISAPP) defines probiotics as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host" — the key words being *adequate amounts*, which is why CFU count and strain identity on the label matter.
04Visit us
William's Natural Foods is at 12249 San Pablo Ave, Richmond, CA 94805 — open Monday–Friday 9–7, Saturday 9–6, and Sunday 10–5. With dozens of probiotic formulas on the shelf, our staff can help you compare strains and find the right fit. Call (510) 232-1911 with questions.
Still Have Questions? Come Talk to Us In Store
The fastest way to get answers is to talk it through in person. Here's how:
This guide is for informational purposes only and isn't medical advice. Talk to a healthcare provider before starting any supplement, especially if you're pregnant, nursing, immunocompromised, or managing a medical condition. These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.