Pistachio Pesto Pasta with Ricotta

What it is

Short pasta and peas, tossed through a bright green pesto of raw pistachios, basil, garlic and lemon, then loosened with ricotta and a splash of the pasta's cooking water until the sauce clings to every piece. Chopped pistachios, lemon zest and basil go on top. One pot and a food processor, no oven.

There's no hard cheese in this pesto, on purpose: the ricotta brings the creaminess and the lemon brings the edge. I'm lacto-vegetarian, so this is a weeknight plate I'd happily cook for you.

It's also Protein Champion number twelve, and pistachios bring a lysine story with a twist: they do real work on this plate, and they need a teammate to finish the job.

Why you should eat it

Here's the short version, before anyone files pistachios under snacks and moves on. USDA FoodData Central lists 20.2 g of protein per 100 g of raw pistachios, the most of anything in this bowl gram for gram, and 10.6 g of fiber in that same 100 g. Small print on the fiber: USDA's newer lab analysis found 7.0 g, so treat it as a range. They're rich, too: 45.3 g of fat per 100 g, 5.91 g of it saturated. Unsalted, they bring almost no sodium (1 mg), so the salt here is the salt you add. Now the honest bit. At 30 g a plate, my sums on those records give the pistachios about 6 g of protein and 2 to 3 g of fiber. The pasta brings more protein, about 10 g, because there's more of it, and the ricotta about 7. This champion is a team player, and I'll show you how while the water heats.

Tips

• Add the cooking water a splash at a time. You can always add more; you can't take it back out.
• Only salted pistachios at home? Skip the 1/2 tsp of salt in the pesto and taste at the end. The card's sodium is built on unsalted ones.
• Want a sharper finish? Grate a little hard cheese labelled as made with non-animal rennet over the top. The card doesn't count it.
• Pistachios are tree nuts. If you or anyone at your table has a tree nut allergy, please choose a different recipe for them; no swap on this page makes this one safe.

Substitutions

• Raw pistachios: Dry roasted unsalted pistachios A toastier pesto. USDA record 170185 lists 21 g of protein and 10.3 g of fiber per 100 g against 20.2 g and 10.6 g raw: the card barely moves.
• Part-skim ricotta: Whole-milk ricotta, made without animal rennet (check the label) Richer and softer. USDA record 170851 lists 7.54 g of protein and 10.2 g of fat per 100 g against 11.4 g and 7.91 g for part-skim: about 2.4 g less protein and 1.4 g more fat per plate, by my count. It has no amino acid values, so the jug sums don't cover it.
• Dried pasta: Whole-wheat dried pasta, still checked for no egg USDA record 169738 lists 9.2 g of fiber per 100 g dry against 3.2 g for regular pasta, so the fiber climbs. Cook it to its packet time; the card is built on regular pasta.
• Frozen peas: Leave them out The plate loses the peas' protein and fiber (USDA lists 5.22 g and 4.5 g per 100 g of frozen peas, record 170016).

Storage

Shallow containers, into the fridge within 2 hours (1 hour if the room is above 90 °F, about 32 °C). Eat within 3 to 4 days, or freeze for 3 to 4 months. Reheat covered, with a splash of water, until it reaches 165 °F (74 °C) on a food thermometer. That's the USDA food safety service's advice for leftovers.

While it cooks: filling the jug to the line

Lid on, water heating, pesto done. Nothing to stir for a few minutes, so come sit with me.

Quick recap from Champion number one: protein is built from amino acids, and nine of them have to come from food. On this plate, one of those nine runs the show: lysine.

Here's the mix, counted in USDA FoodData Central's records. Of every 100 g of protein, lysine makes up 2.29 g in dry pasta, 5.64 g in raw pistachios and 11.84 g in part-skim ricotta. The FAO's 2013 expert report puts a reference line for older children, teenagers and adults at 4.8 g. Pasta sits well under it, pistachio clears it, and ricotta clears it more than twice over.

Teacher hat on. Picture a jug of juice mixed from three cartons of different strengths. Pasta is the weakest carton, but you pour the most of it: 320 g of dry pasta brings about 42 g of protein. Pistachios pour less, and stronger. Ricotta pours strongest of all. Where the jug lands depends on how strong each pour is and how much of it goes in.

So let's fill it, with my own arithmetic on those records. Pasta alone: 2.29, under the line. Add the pistachios: 3.53, closer, still under. Add the ricotta: 6.04, over. The peas and basil keep it at about 6.0. The sulfur pair (methionine and cysteine) gives no trouble tonight: all three main foods sit over FAO's 2.3.

The jug picture stops in two places. A jug doesn't digest anything, and you do: these shares are counted before digestion takes its cut, and when pistachio protein was graded after digestion (in pigs, more in case one), lysine came out as its weakest link, the very amino acid ricotta brings in bulk. And you aren't one jug per meal: even the review in case one, written at the pistachio growers' request, says protein quality is better judged across your whole diet.

So, in one line: pasta brings the volume, pistachios lift the lysine about halfway to the line, and ricotta carries the bowl over it.

Case one: the growers' report card on pistachio protein

Four authors wrote this one, and the funding line is refreshingly blunt: the American Pistachio Growers 'had the concept for this manuscript' and paid for the writing. One of the four works for them. Keep that in your pocket.

It's a narrative review, with no search method and no pooled analysis. Its protein grades come from one study in growing pigs, scored with DIAAS, the method the FAO recommended in 2013. DIAAS looks at the essential amino acids actually digested by the end of the small intestine, and the one that falls furthest short of a reference sets the grade.

The grades: 86 for raw pistachios and 83 for roasted, for older children, teenagers and adults, with lysine falling short. The FAO report gives 75 to 99 as an example band for a 'good' protein source and 100 or more for 'excellent'.

Then the label. The review calls pistachios 'a plant-based complete protein providing all nine EAAs' (essential amino acids). All nine are in there, sure. Its own grade says one of them comes up a little short after digestion.

For your plate: by the one digestibility test the review leans on, pistachio protein lands in the good band, and its weak spot is the thing your ricotta brings.

Where it stops: the authors say DIAAS rests on animal models and isn't directly applicable to humans. I could open the pig study only in its summary, so I can't tell you how many pigs or who paid for it. And the growers commissioned the review. Useful numbers, from a paper with a stake in them.

Case two: pistachios on top of pasta

Ten healthy volunteers, studied by a Toronto team: three men and seven women, average age 48. In the tests that matter here, they came in fasted on separate mornings and ate pasta, parboiled rice or mashed potatoes, each portion carrying 50 g of available carbohydrate, either on its own or with 56 g of pistachios. Their blood sugar was followed for two hours and scored against white bread, which counts as 100.

The pasta scored 94.8 on its own and 56.4 with pistachios, about 40% lower on my calculator. Rice went from 72.5 to 58.7. The potatoes went from 109.0 to 87.4, just short of the usual 0.05 cut-off (P = 0.063).

For your plate: this is the closest any study I found comes to this bowl. Same pasta, gentler rise. But they ate 56 g of pistachios per 50 g of carbs, and a plate here carries 30 g per roughly 71 g, a little over a third of that ratio, so don't carry the 40% over.

Where it stops: ten people, one sitting per test, nobody with diabetes. I could open only the published summary, so I can't tell you the authors' own limits, which pasta they used or who funded it. Promising, and small. If you're managing your blood sugar, take this to your doctor. A recipe can't make that call for you.

Case three: a nightly handful, twelve weeks, a straight answer

Sixty-six adults with prediabetes at Penn State, 39 men and 27 women, average age 51; 51 finished. Each went through two 12-week stretches in random order, at least four weeks apart. In one, they ate 57 g of dry roasted, unsalted pistachios every night after dinner. In the other, they were taught to keep the night snack to 15 to 30 g of carbs and got a grocery gift card worth about the same as the nuts.

The internet would love a 'pistachios fix blood sugar' headline here. The trial says no, plainly. Fasting blood sugar, the main outcome, differed by 0.9 mg/dL, and the authors say a meaningful effect is unlikely to have been missed. HbA1c (long-term blood sugar), insulin, blood fats and blood pressure didn't differ either.

What changed was the rest of the menu: in the pistachio stretch, diet quality scored 6.8 points higher on the US Healthy Eating Index, fiber ran 4.6 g a day higher and refined grains came down. Weight crept up 0.7 kg within that stretch, not significantly different from the other.

For your plate: a nightly pistachio habit didn't move blood sugar here. It went with a better menu, which the authors treat as a lead to test, not an answer.

Where it stops: COVID-19 paused the trial and 13 people withdrew, the age limit dropped from 75 to 65 after the restart, nobody could be blinded to eating nuts, and diet was one day's recall at each point. The American Pistachio Growers funded it, with no role in the design, analysis or writing, alongside a US National Institutes of Health grant. A snack study, not a pasta study, with a straight answer.

Case four: pistachios after a downhill run

Forty moderately trained young men at San Diego State signed up and 27 finished, most dropouts down to COVID-19. Average age 24. Each went through three two-week blocks in random order: no pistachios, 42.5 g a day or 85 g a day. After each block came a punishing 40-minute downhill treadmill run, the kind that leaves your legs sore for days, then tests at 24, 48 and 72 hours: leg strength, jump height, pain ratings and blood markers of muscle damage.

Soreness peaked at 24 hours every time. Only on 85 g did pain return to baseline in most leg muscles by 72 hours, and the differences against no pistachios that cleared the statistics were all in the glutes: at 72 hours, the right glute rated 8.2 mm on the high dose and 8.4 on the lower one against 13.2 with none, on a 100 mm pain scale. Jump height didn't change, and the blood markers showed, in the authors' words, 'no advantages following pistachio consumption'.

For your plate: pistachios, the high dose most of all, went with less sore glutes two and three days later. Jump height and the blood markers showed no benefit. A plate here holds 30 g; the high dose was 85 g a day for two weeks.

Where it stops: men only, 27 of them, one kind of muscle damage, and self-rated pain with no blinding described. The authors add that the break between blocks may not erase the 'repeated bout' effect, where a second round of the same punishing exercise hurts less than the first. The growers paid, with no involvement in the work. A nice hint for sore glutes, and that's all: my searches found no human study of pistachios and building muscle.