Cereal, O's, plain
Common food
Photo: Wikipedia
Plain O-shaped cereal is a classic, toasted oat ring with a light, crunchy texture and a subtly sweet, nutty flavor. It's a high-fiber, moderate-protein breakfast staple designed for a satisfying, low-sugar start to the day. Its simple profile makes it a versatile base for both sweet and savory applications.
Calorie split: 13% protein · 72% carbs · 15% fat
↓ Full nutrition💚 Why it's loved
People love it for its reliable, comforting crunch and mild flavor that pairs perfectly with milk, yogurt, or fruit. Its iconic shape and nostalgic appeal make it a beloved, no-fuss breakfast or snack for all ages.
⚠️ Watch-outs & how to enjoy it better
Its high carbohydrate content can cause blood-sugar spikes if eaten alone, especially by those with insulin sensitivity. To counteract this, pair it with a source of protein or fat (like Greek yogurt, nuts, or seeds) and be mindful of portion size. Some brands may also be processed in facilities with common allergens like wheat or nuts.
Key benefits
- Excellent source of dietary fiber (10.5g per 100g)
- Provides plant-based protein (12.42g per 100g)
- Low in sugar (only 4.9g per 100g)
- Convenient, shelf-stable, and quick to prepare
- Often fortified with essential vitamins and minerals
🍽️ Popular dishes
🌍 Where it's eaten
💡 Did you know?
The O-shape was patented in 1941 and was originally designed to prevent the cereal from becoming soggy too quickly by minimizing the surface area in contact with milk.
Full nutrition (USDA data · scales with serving)
| Water | 10.3 g |
| Energy | 374 kcal |
| Protein | 12.4 g |
| Total lipid (fat) | 6.2 g |
| Carbohydrate, by difference | 67.9 g |
| Fiber, total dietary | 10.5 g |
| Total Sugars | 4.9 g |
| Calcium, Ca | 368 mg |
| Iron, Fe | 30.9 mg |
| Magnesium, Mg | 130 mg |
| Phosphorus, P | 387 mg |
| Potassium, K | 342 mg |
| Sodium, Na | 506 mg |
| Zinc, Zn | 3.4 mg |
| Copper, Cu | 0.37 mg |
| Selenium, Se | 27.3 ug |
| Vitamin C, total ascorbic acid | 22.9 mg |
| Thiamin | 0.88 mg |
| Riboflavin | 0.63 mg |
| Niacin | 7.0 mg |
| Vitamin B-6 | 0.73 mg |
| Folate, total | 150 ug |
| Folic acid | 119 ug |
| Folate, food | 30.0 ug |
| Folate, DFE | 233 ug |
| Choline, total | 38.2 mg |
| Vitamin B-12 | 0.90 ug |
| Vitamin B-12, added | 0.90 ug |
| Vitamin A, RAE | 0.00 ug |
| Retinol | 0.00 ug |
| Carotene, beta | 0.00 ug |
| Carotene, alpha | 0.00 ug |
| Cryptoxanthin, beta | 0.00 ug |
| Lycopene | 0.00 ug |
| Lutein + zeaxanthin | 170 ug |
| Vitamin E (alpha-tocopherol) | 0.40 mg |
| Vitamin E, added | 0.00 mg |
| Vitamin D (D2 + D3) | 5.0 ug |
| Vitamin K (phylloquinone) | 1.9 ug |
| Alcohol, ethyl | 0.00 g |
| Caffeine | 0.00 mg |
| Theobromine | 0.00 mg |
Fat & fatty acid profile (per 100g)
| Fatty acids, total saturated | 1.0 g |
| SFA 4:0 | 0.00 g |
| SFA 6:0 | 0.00 g |
| SFA 8:0 | 0.00 g |
| SFA 10:0 | 0.00 g |
| SFA 12:0 | 0.02 g |
| SFA 14:0 | 0.01 g |
| SFA 16:0 | 0.89 g |
| SFA 18:0 | 0.06 g |
| Fatty acids, total monounsaturated | 1.9 g |
| MUFA 16:1 | 0.01 g |
| MUFA 18:1 | 1.9 g |
| MUFA 20:1 | 0.00 g |
| MUFA 22:1 | 0.00 g |
| Fatty acids, total polyunsaturated | 2.2 g |
| PUFA 18:2 | 2.1 g |
| PUFA 18:3 | 0.09 g |
| PUFA 18:4 | 0.00 g |
| PUFA 20:4 | 0.00 g |
| PUFA 20:5 n-3 (EPA) | 0.00 g |
| PUFA 22:5 n-3 (DPA) | 0.00 g |
| PUFA 22:6 n-3 (DHA) | 0.00 g |
| Cholesterol | 0.00 mg |
Amino acid profile (per 100g)
Estimated from Cereals ready-to-eat, POST, HONEY BUNCHES OF OATS, honey roasted — USDA does not publish this profile for Cereal.
| Tryptophan | 0.09 g |
| Threonine | 0.24 g |
| Isoleucine | 0.26 g |
| Leucine | 0.80 g |
| Lysine | 0.12 g |
| Methionine | 0.10 g |
| Cystine | 0.11 g |
| Phenylalanine | 0.39 g |
| Tyrosine | 0.21 g |
| Valine | 0.34 g |
| Arginine | 0.24 g |
| Histidine | 0.18 g |
| Alanine | 0.46 g |
| Aspartic acid | 0.48 g |
| Glutamic acid | 1.9 g |
| Glycine | 0.27 g |
| Proline | 0.49 g |
| Serine | 0.38 g |
FAQ
Is plain O cereal healthy?
It can be a healthy part of a balanced diet. Its high fiber content supports digestion, and it's low in sugar. However, it's best enjoyed with added protein or fat to create a more balanced meal and prevent energy crashes.
Can I use this cereal in cooking?
Absolutely! It's excellent crushed as a breading for meats or vegetables, mixed into granola bars, or even sprinkled over desserts for added crunch.
How does it differ from sugary kids' cereals?
Plain O cereal has significantly less sugar (often less than 1g per serving) and more fiber than most colorful, sweetened cereals, making it a more nutritious foundational choice.
Nutrient density (calculated · NRF9.3)
Nutrient Rich Foods index: beneficial nutrients (protein, fiber, vitamins, minerals) minus saturated fat, added sugar & sodium, per 100 kcal.
NRF9.3 index — Fulgoni, Keast & Drewnowski, 2009. Computed from USDA nutrients.
Weight-loss friendliness (composite index)
Energy density 3.74 kcal/g · 13% calories from protein · 10.5 g fiber · 4.9 g sugar per 100 g.
Composite of energy density (Rolls et al., 1999), protein & fiber satiety, minus sugar. A calculated heuristic — ranks satiety-per-calorie, not a clinical measure.
Dietary load (calculated from USDA values)
Potential renal acid load. Positive = acid-forming, negative = alkaline-forming.
Sodium-to-potassium ratio: 1.48 (lower is better — aim for ≤ 1)
Sodium:potassium per WHO potassium guidance. Computed from USDA nutrients.