Is quinoa acidic or alkaline? Its acid load, worked out

Mildly acid-forming. Run cooked quinoa through the standard potential renal acid load (PRAL) formula and it scores about +2.3 per 100 g, level with cooked brown rice and close to lentils (our arithmetic from USDA data). That shifts your urine a little, not your blood: diet changes move urine pH, while blood pH barely moves.

The old version of this page said the opposite. It called quinoa an alkaline food, listed lentils among its gently alkaline company, and warned that an acidic diet dissolves your bones. Put the USDA’s own nutrient figures into the formula researchers actually use and the first two claims fall over. Quinoa comes out at +2.28 per 100 g cooked. Cooked long-grain brown rice comes out at +2.29. Lentils land at +2.15 (all our arithmetic). By this measure quinoa behaves like brown rice, which is fine, because the bone scare behind the question does not hold up either. The calcium side of that worry has its own answer, in our piece on whether a vegan diet leads to calcium deficiency.

What does acidic or alkaline mean for a food?

It can mean two different things.

The first is how acidic the food is in your mouth. That is the sense that matters for heartburn, and NIDDK, the US institute for digestive diseases, uses it when it lists foods that may make acid reflux worse: acidic foods such as citrus fruits and tomatoes, alongside alcohol, chocolate, caffeine, high-fat foods, mint and spicy foods. Quinoa is not on that list. The old page gave quinoa a pH of 6.7. Nothing we read for this article measured the pH of cooked quinoa, so that number is gone.

The second sense is what a food leaves behind once your body has used it, and that is what the alkaline-diet charts mean. In 1995 the researchers Remer and Manz published a way to estimate it, the potential renal acid load, from a food’s nutrient content. Their model was validated as an estimate of the acid the kidneys excrete, and they found it predicts the effect of diet on the acidity of urine. Positive numbers mean acid for the kidneys to clear. In their calculations, foods ranged from an average high of 23.6 mEq per 100 g for some hard cheeses, through 0 for fats and oils, down to about -3 for fruits, fruit juices and vegetables on average.

The version most studies use today takes five numbers. Protein and phosphorus push the score up; potassium, magnesium and calcium pull it down. PRAL = (0.49 × protein in g) + (0.037 × phosphorus in mg) − (0.021 × potassium in mg) − (0.026 × magnesium in mg) − (0.013 × calcium in mg). You can do it on the back of a quinoa bag, provided the bag lists all five.

Where quinoa lands, worked out

Here are the USDA’s figures per 100 g for cooked quinoa and three foods to compare it with, and the score each one gets.

Food, per 100 g	Protein	Phosphorus	Potassium	Magnesium	Calcium	PRAL (our arithmetic)
Quinoa, cooked	4.4 g	152 mg	172 mg	64 mg	17 mg	+2.28
Brown rice, long-grain, cooked	2.74 g	103 mg	86 mg	39 mg	3 mg	+2.29
Lentils, boiled	9.02 g	180 mg	369 mg	36 mg	19 mg	+2.15
Spinach, raw	2.86 g	49 mg	558 mg	79 mg	99 mg	−11.84

Quinoa does carry more of the alkalizing minerals than brown rice: twice the potassium and more magnesium. The alkaline charts were not inventing that. They just stopped reading before the protein and phosphorus lines, which are also higher, and which cancel the gain almost to the decimal. Spinach shows what an alkaline food looks like in this system, with more than three times quinoa’s potassium per 100 g (our arithmetic) and far less protein.

A typical serving makes the number smaller still. The USDA weighs a cup of cooked quinoa at 185 g, which works out to about +4.2 per cup (our arithmetic). The researchers who ran a 2021 vegan diet trial describe meat, cheese, fish, eggs and certain grains such as oats and processed wheat products as acid-forming foods. Quinoa sits with the grains, at the mild end.

Does an acid-forming food make your body acidic?

No. A 2016 systematic review in BMJ Open describes a randomized trial in which changing the diet moved urine pH by 1.02 units and systemic pH by 0.014. Across three studies that measured both, the reviewers found urine pH shifting by 0.2 to 1.2 units while blood pH changed minimally, and concluded that the kidneys are effective at excreting acid and that urine pH is not a measure of the body’s pH. Testing your urine and then eating quinoa to fix the reading tells you about your urine.

The bone claim fares no better. A 2011 systematic review and meta-analysis of 55 studies concluded that a causal link between dietary acid load and osteoporotic bone disease is not supported by evidence, and that there is no evidence an alkaline diet protects bone. The same 2016 review looked for evidence linking diet acid load or alkaline water to cancer, found a single eligible study showing no association with bladder cancer, and concluded that promoting an alkaline diet for cancer prevention or treatment is not justified. The old page’s list of acidosis symptoms, from tiredness to hair and nails, had no source behind it and is gone.

The strongest case for caring about acid load

Acid load is a real, measurable quantity, and serious researchers study it. Urine acidity does follow diet, and Remer and Manz built their method partly for practical dietetics such as preventing recurrent kidney stones, where a target urine pH is the point. Some prospective studies have linked a higher dietary acid load to type 2 diabetes and to high blood pressure. If you take those studies seriously, the acid your diet produces is worth some attention.

The same review that reports those links adds that their effects were small, below the threshold usually taken to suggest an important association, and that other prospective studies found no link to diabetes or hypertension. And even on the case’s own terms, single foods are the wrong unit. In the 2021 trial, healthy omnivores were randomized to an isocaloric vegan diet or a meat-rich one for 4 weeks. After 3 weeks the vegan group’s median PRAL was -23.57 against +18.78 in the meat-rich group, a difference the authors traced to lower protein and phosphorus intake. That is a gap of about 42 points (our arithmetic). A cup of quinoa adds about 4. If acid load worries you, the vegan diet you already eat has done most of the work, and swapping rice for quinoa leaves the PRAL arithmetic where it was.

What we are least sure of is the precision. Every PRAL figure on this page is arithmetic on USDA average values, not a measurement of anyone’s urine. Nothing we read put any quinoa below zero, but we tested none ourselves, and a variety with a very different mineral profile would score differently. If you are eating it for its protein rather than its pH, that question has better numbers behind it, in our piece on whether vegans get enough protein.