Tempeh
Food · Protein · Food, Typed Supps
Tempeh is fermented soybeans pressed into a firm, nutty cake -- fermentation makes its protein and minerals easier for your body to use than plain soybeans.
Stage by stage
- Chewing & Breakdown (Mouth): Chewing breaks apart the firm, mycelium-bound soybean cake, which fermentation has already partially predigested before it ever reaches the stomach.
- Protein Breakdown (Stomach): Stomach acid and pepsin continue breaking the soy proteins down into smaller peptides, aided by fermentation's reduction of trypsin-inhibitor activity that would otherwise blunt this process.
- Absorption (Small Intestine): In the small intestine, peptides are broken into amino acids and absorbed along with minerals like iron and manganese, whose availability fermentation has improved by degrading much of the soybean's original phytic acid.
- Muscle Uptake (Muscle Tissue): Amino acids and isoflavones travel through the bloodstream to muscle and other tissues, where they support protein synthesis, tissue repair, and other physiological functions.
Timing
Tempeh's iron is nonheme, so eating it alongside vitamin C-rich vegetables or fruit in the same meal can help improve iron absorption.
Time to effect
- Weeks: A meal built around tempeh raises circulating amino acids and isoflavones within a few hours, but measurable effects on muscle maintenance or blood lipids from regular consumption take several weeks to appear.
Allergens
Contains: Soya. Derived from what this food is, not from a product label.
Eating patterns
Fits: Vegan, Vegetarian, Pescatarian, Halal, Kosher, Low-FODMAP, Gluten-free. Depends on the product: Keto.
Satiety
139 on the satiety index, where white bread is 100 — moderate. Modelled from the Holt et al. (1995) measurements.
Environmental footprint
3.2 kg CO2e and 149 litres of freshwater per kg, matched to "Tofu" in Poore & Nemecek (2018), Science 360.
Cost band
Mid — roughly £7 per kg, as a band midpoint rather than a price.
Key nutrients
Nutrition per 100g
- Calories: 192
- Protein: 20.3g
- Carbohydrate: 7.6g
- of which sugars: 0g
- Fat: 10.8g
- of which saturated: 2.2g
- Fibre: 0g
- Sodium: 9mg
Food vs. supplement
Whole tempeh provides protein together with fiber, minerals, and fermentation-derived isoflavone aglycones in one food matrix, while isolated soy protein powders or isoflavone supplements concentrate specific components but leave out the fiber and whole-food fermentation benefits.
Kitchen tip
Steam or briefly par-boil sliced tempeh for about 10 minutes before marinating, frying, or grilling it -- this softens its firm texture, tones down surface bitterness, and helps marinades penetrate the cake.
Common myth
"Tempeh, because it's a fermented food, is a reliable vegan source of vitamin B12." In reality: Analyses of commercially produced tempeh made with pure Rhizopus oligosporus starter culture have found vitamin B12 undetectable or present only in trace amounts (around 0.05 mcg per 100 g, well under 2% of the adult RDA); meaningful B12 levels documented in some traditional or research tempeh came from incidental or deliberately added B12-producing bacteria such as Citrobacter freundii or Klebsiella pneumoniae, not from the Rhizopus mold or fermentation process itself, so vegans should not rely on typical tempeh for B12.
Recipes that use it
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