Do You Need Supplements on a Low Glycemic Diet?
An honest look at what the evidence supports, what it doesn't, and why the marketing runs well ahead of the research.
"Do you recommend supplements?" · "What about berberine?"
Short version: no supplement substitutes for the eating pattern, and most are oversold. Here's the honest picture on the common ones.
What has reasonable evidence
Magnesium. Deficiency is genuinely common, and it's involved in insulin signalling. If you're low, correcting it is worthwhile. If you're not, supplementing probably does little. A blood test is more useful than guessing.
Vitamin D. Same logic. Deficiency is widespread, particularly at northern latitudes and in older adults, and it's associated with insulin resistance. Whether supplementing improves glucose in people who aren't deficient is much less clear.
B12 if you take metformin. Long-term metformin use is associated with reduced B12 absorption. This is a genuine, documented interaction and worth periodic testing.
What's promising and oversold
Berberine. This has real research behind it for glucose, and it's the reason it's marketed as "nature's Ozempic" — a phrase that should make you sceptical rather than interested. It's a pharmacologically active compound with drug interactions, and it isn't regulated as a medication. If you're on diabetes medication, taking it without telling your prescriber is a genuinely bad idea.
Cinnamon. Modest, inconsistent results across studies. Cheap and harmless in food quantities, and I'd rather you put it in your oatmeal than buy capsules.
Inositol. Reasonable evidence in PCOS specifically, less elsewhere.
What I'd be sceptical of
Anything marketed as a blood sugar "support formula" with a long ingredient list and small amounts of each. Proprietary blends that don't disclose per-ingredient doses. Anything promising an effect on A1C, which is a disease claim a supplement isn't permitted to make.
The three questions worth asking
Am I actually deficient? Test rather than assume.
Does this interact with my medication? Ask a pharmacist — they're free, expert on exactly this, and underused.
Would this money do more as food? Frequently yes. The protein you're short of at breakfast will do more than most bottles.
The honest summary
Supplements sit at the margin. The eating pattern, the protein target, the walk after meals and the sleep are where the effect is. Anyone telling you otherwise is usually selling something.
Try this week: if you take metformin, ask when your B12 was last checked. That's the one on this list most likely to matter and least likely to have been done.
Education, not medical advice. Discuss any supplement with your doctor or pharmacist, particularly alongside prescribed medication.