Oyster Mushroom Glycemic Index
Low GI · The honest verdict
Gentle on blood sugar
Glycemic index
15
per source
Glycemic load
1
Low GL
This food's glycemic index is 15, which is Low GI.
Oyster mushrooms are among the most blood-sugar-friendly foods available. With only about 2.8 g of net carbs per cup and a very low GI, they have minimal impact on blood glucose. Their fiber and protein content can even help moderate the glycemic response of a mixed meal. This is general nutrition information, not medical advice — people with diabetes should confirm with their care team.
GI numbers vary by source, ripeness, and how a food is prepared. This is general nutrition information — not medical advice. If you manage diabetes, confirm specifics with your care team.
Key facts
Oyster mushrooms have a very low GI of about 15 — negligible impact on blood sugar.
One cup of raw oyster mushrooms contains only 2.8 g of net carbs and 28 calories.
Oyster mushrooms provide 3.9 mg of niacin per cup — about 24% of the daily value.
What's actually inside
Per 100 g, with your typical serving noted as 1 cup (86 g), sliced, raw. The carb family is what moves blood sugar — fiber is the number that softens the spike.
- Total carbs
- 5.1g
- Net carbs
- 2.8g
- total carbs minus fiber
- Fiber
- 2.3g
- slows the glucose rise
- Sugars
- 1.1g
- Protein
- 2.8g
- Calories
- 28kcal
Notable nutrients
- Niacin (Vitamin B3)3.9 mg
- Pantothenic acid (Vitamin B5)1.0 mg
- Copper0.2 mg
- Potassium420 mg
- Zinc0.8 mg
Is it a smart choice for blood sugar?
GI is only half the story — portion (glycemic load) and what you eat it with decide the real-world effect. Here's the honest read.
The verdict
Excellent — very low carb, low GI, diabetes-friendly
Oyster mushrooms are among the most blood-sugar-friendly foods available. With only about 2.8 g of net carbs per cup and a very low GI, they have minimal impact on blood glucose. Their fiber and protein content can even help moderate the glycemic response of a mixed meal. This is general nutrition information, not medical advice — people with diabetes should confirm with their care team.
Portion guidance
There is no meaningful carbohydrate restriction with oyster mushrooms. A full cup (86 g) contains under 3 g of net carbs, making them a free vegetable on most diabetes and low-carb plans. They can be eaten in generous portions without concern for blood sugar. Pairing them with other low-GI vegetables and a protein source makes for an ideal diabetes-friendly meal.
This is general nutrition information, not personal medical advice. Blood sugar responses are individual — if you have diabetes or prediabetes, your care team can tell you how this fits your plan.
How to keep the spike small
The same food can land differently depending on how it's cooked and what it's eaten with. Use these levers to your advantage.
Sautéing in oil or butter
Little effectSautéing adds fat but does not meaningfully change the GI of the mushrooms themselves. The added fat can slightly slow gastric emptying, which may modestly lower the overall glycemic impact of a meal.
Roasting or grilling
Little effectDry-heat methods like roasting or grilling concentrate flavor and reduce water content but do not significantly alter the carbohydrate structure or GI of oyster mushrooms.
Adding to soups or stews
Little effectCooking oyster mushrooms in liquid does not raise their GI. The mushrooms absorb some liquid, but their carbohydrate content and glycemic impact remain very low.
Pairing tip
Oyster mushrooms pair well with any protein — chicken, fish, tofu, or eggs — for a balanced, blood-sugar-friendly meal. Combine them with non-starchy vegetables like spinach, bell peppers, or broccoli for a low-carb plate. Avoid heavy cream sauces or breading, which add carbs and fat that can affect overall meal glycemic load.
Why GI numbers vary
Very few formal GI studies exist for oyster mushrooms specifically, but the available data and the known composition of mushrooms (very low carbohydrate, high fiber) consistently indicate a very low GI — approximately 15 or lower. Mushrooms as a category are considered negligible-GI foods. The value is so low that minor variations between sources do not change the practical classification.
Not medical advice. This page is general nutrition information about Oyster Mushroom. It isn't a diagnosis or a treatment plan. If you have diabetes, prediabetes, or another condition affecting blood sugar, confirm any dietary decisions with your doctor or care team.
Frequently Asked Questions
Oyster mushrooms have a very low glycemic index, estimated at around 15. This is because they contain very little carbohydrate — about 5 g total per cup — and most of that is fiber. They are classified as a low-GI food and have minimal impact on blood sugar. The exact value may vary slightly between sources, but all place them firmly in the very low range.
Yes, oyster mushrooms are an excellent food choice for people with diabetes. They are very low in carbohydrates, have a negligible glycemic load, and provide fiber and protein that support stable blood sugar. They also contain B vitamins and minerals like copper and potassium. This is general nutrition information — people with diabetes should discuss their diet with their care team.
Absolutely. With only about 2.8 g of net carbs per cup, oyster mushrooms fit easily into even the strictest ketogenic diet. They are a popular low-carb vegetable and can be used as a meat substitute in many dishes. Their umami flavor makes them a satisfying addition to keto meals without risking ketosis.
All common edible mushrooms — including white button, cremini, shiitake, and portobello — are very low in carbohydrates and have a negligible GI. Oyster mushrooms are similar to these in their glycemic impact. The main nutritional differences are in micronutrient profiles: oyster mushrooms are particularly rich in niacin and pantothenic acid.
No, cooking does not meaningfully change the GI of oyster mushrooms because they contain very little starch. Unlike starchy vegetables where cooking gelatinizes starch and raises GI, oyster mushrooms' carbohydrate content is primarily fiber and small amounts of sugar. Sautéing, roasting, or adding them to soups keeps them firmly in the very-low-GI category.
Yes, oyster mushrooms provide about 2.3 g of fiber per cup, which is roughly 8% of the daily recommended intake. This fiber content contributes to their low net carb count and helps slow digestion, further supporting stable blood sugar levels. The fiber is primarily beta-glucans, a type of soluble fiber associated with heart health benefits.
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Reviewed by
Curex Editorial TeamReviewed for accuracy
Last reviewed July 2026