Pork is the single richest common food source of vitamin B1 (thiamine), delivering about 0.9 mg per 100 grams of lean meat. That alone covers roughly 75% of the daily value of 1.2 mg. But pork is far from the only option. Thiamine shows up in legumes, whole grains, nuts, fortified cereals, and certain vegetables, making it easy to hit your daily target through a variety of foods.
What Vitamin B1 Does in Your Body
Thiamine helps your cells convert carbohydrates into usable energy. Without it, your body can’t properly process pyruvate, a molecule central to dozens of chemical reactions that keep your metabolism running. Thiamine also supports muscle contraction and the transmission of nerve signals, which is why a deficiency tends to show up first as fatigue, weakness, or tingling in the extremities.
Best Animal Sources
Pork stands well above other meats. Lean pork contains about 0.9 mg of thiamine per 100 grams, while pork ribs come in around 0.65 mg. No other common meat comes close. Beef shank and chicken breast each provide only about 0.06 mg per 100 grams, so they contribute very little on their own.
Eggs offer a modest amount. A raw duck egg has around 0.13 mg per 100 grams. Fish varies widely: mackerel provides about 0.11 mg per 100 grams, while some freshwater species fall in the same range. Shellfish like freshwater shrimp sit lower, around 0.07 mg. If you’re relying on animal foods for your thiamine, pork is doing the heavy lifting.
Best Plant Sources
Peanuts are one of the top plant sources, matching galangal root at 1.10 mg per 100 grams. A handful of peanuts as a snack can cover a meaningful chunk of your daily needs. Dried mung beans follow at 0.73 mg per 100 grams, and black beans provide about 0.4 mg per half cup when cooked, covering 33% of the daily value.
Whole grains contribute moderate amounts. Brown rice delivers about 0.2 mg per half cup cooked (17% of the daily value), while white corn comes in around 0.30 mg per 100 grams raw. White polished rice, on the other hand, drops to just 0.09 mg per 100 grams, a clear illustration of how much thiamine is lost when the bran and germ are stripped away.
Among vegetables, garlic provides 0.24 mg per 100 grams, and several greens and pods fall in the 0.10 to 0.18 mg range, including yard-long beans, winged bean pods, and mung bean sprouts. Sweet potatoes sit around 0.11 mg. These aren’t powerhouse sources individually, but they add up across a varied diet.
Fortified Foods Fill the Gap
A single serving of breakfast cereal fortified with 100% of the daily value delivers the full 1.2 mg of thiamine. In countries where refined grains are dietary staples, fortification is the main reason most people don’t become deficient. Enriched white bread, for example, contains about 0.18 mg per 100 grams, putting back some of what milling removed. If your diet leans heavily on processed grains, checking labels for thiamine enrichment is worth the two seconds it takes.
Cooking Destroys a Lot of Thiamine
Thiamine is one of the more fragile vitamins. Studies show that cooking and processing can destroy 50% to 84% of the thiamine in food, depending on temperature, cooking time, pH, and the food itself. Heat is the primary culprit, but alkaline conditions (like adding baking soda to cooking water) and exposure to light also accelerate the loss.
Practical takeaways: shorter cooking times preserve more thiamine. Steaming or microwaving retains more than boiling, partly because thiamine is water-soluble and leaches into cooking water that often gets discarded. If you’re making soup or stew where you consume the liquid, that lost thiamine stays in the meal.
What Blocks Thiamine Absorption
Several common substances interfere with how well your body absorbs and uses thiamine. Coffee, tea, blueberries, and other foods rich in tannins and polyphenols can reduce absorption when consumed at the same time as thiamine-containing foods. The simplest workaround is to space them apart rather than drinking tea with your meal.
Alcohol is the most significant thiamine antagonist. Heavy drinking reduces dietary intake, impairs absorption in the small intestine, and damages the liver’s ability to transport thiamine. Chronic alcohol use is the leading cause of severe thiamine deficiency in developed countries, sometimes progressing to a condition called Wernicke-Korsakoff syndrome, which involves confusion, memory loss, loss of coordination, and vision problems. In extreme cases it can progress to coma.
Raw fish and shellfish contain enzymes called thiaminases that break thiamine into inactive forms. Cooking neutralizes these enzymes, so this is primarily a concern for people who eat large amounts of raw seafood regularly.
How Much You Need
The daily value for thiamine is 1.2 mg for adults. That’s a small number, and most people eating a varied diet that includes some combination of pork, legumes, nuts, or fortified grains will meet it without thinking about it. There is no established upper limit for thiamine intake because your body excretes excess amounts in urine, and toxicity from food sources has not been documented.
People at higher risk for falling short include those who eat mostly polished white rice without fortification, heavy drinkers, and individuals with conditions that impair nutrient absorption. Early signs of mild deficiency are nonspecific: fatigue, irritability, and reduced appetite. Severe deficiency, known as beriberi, affects the heart and nervous system but is rare in populations with access to varied food.
Putting It Together
A realistic day of eating that covers your thiamine needs might look like this: a bowl of fortified cereal at breakfast (1.2 mg, full daily value on its own) or a pork-based dinner (a 150-gram serving of lean pork delivers roughly 1.35 mg). Even without those anchor foods, a combination of peanuts, black beans, brown rice, and vegetables can get you there. The key is variety, cooking gently when possible, and not washing your meal down with tea or coffee if thiamine intake is a concern.