I make a protein smoothie 4 to 5 times a week. It's basically non-negotiable at this point — to break my intermittent fast, or as a snack to hit my protein goals for the day. I know I'm not alone.

So when recently I was on the phone with the CEO of a very well-known national smoothie chain — one you definitely know — and asked him: does your vegan protein powder have added BCAAs to make it a complete protein? … and he had no idea what I was talking about, I was shocked and kind of appalled.

This is the problem. At a moment when Starbucks is offering protein boosters in your coffee, and when everyone is suddenly obsessed with protein — for good reason, it's one of the most powerful longevity levers we have — the quality of what we're consuming is getting almost zero attention.

And the stakes are real.

Meanwhile, most vegan protein powders being scooped into smoothies at juice bars and gyms across the country aren't even complete proteins — meaning they can't effectively build the muscle you're counting on them to build.

This week: a no-nonsense guide to choosing a protein powder that actually works.

If you want a personalized protein strategy — how much, what type, when — book a consult with a Parsley clinician →

Choose your protein powder like this:

👉 Forward this to the friend who has been scooping protein powder into everything but has never looked at the label.

❌ The old assumption: Protein is protein. As long as the label says 20 grams, you're good.

✅ The new reality: The type of protein, whether it's complete, how it's sourced, and whether it's been independently tested for safety vary enormously. The FDA does not review or approve protein powders before they hit the market. It's on you to know what you're buying.

Whey comes from dairy — it's a byproduct of cheesemaking. It's a complete protein, naturally high in leucine (the amino acid that triggers muscle protein synthesis), and digests quickly. The research on whey for muscle building is extensive and consistent.

Two forms to know:

For sourcing: choose grass-fed when possible. It matters for the overall quality of the dairy and avoids synthetic hormones (rBGH/rBST).

This is what I use — Parsley's Rebuild, a pea and rice blend. Done right, a pea-rice blend performs comparably to whey for muscle building (Journal of the International Society of Sports Nutrition, 2015).

Here's what most people — including that smoothie chain CEO — don't know:

Pea protein alone is low in methionine. Rice protein alone is low in lysine. Together, they cover each other's gaps. But the blend also needs added BCAAs, particularly leucine, to reach the threshold for triggering muscle protein synthesis. Most plant protein powders on the market don't do this. They are not complete proteins. The label won't always tell you clearly — look for "added BCAAs," "leucine fortified," or a BCAA content listed in the nutrition panel.

If you're relying on them to build muscle, you may not be getting what you think.

Collagen is not a complete protein. It's missing tryptophan entirely and is low in several other essential amino acids — which means it cannot effectively trigger muscle protein synthesis on its own.

What it is genuinely good for: skin elasticity, joint pain, tendon health. A 2025 meta-analysis of 11 studies found collagen supplementation led to significant improvements in pain and function in people with knee symptoms (PMC, 2025). Female skin loses approximately 30% of its collagen in the first five years after menopause — so this matters more as we age.

Use collagen as an add-on, not a replacement. 10–15g daily alongside your complete protein, ideally with vitamin C to support absorption.

Plants pull heavy metals from soil — it's not specific to protein powder, it's the same reason we find trace metals in rice, dark chocolate, and root vegetables. But the concentration process involved in making powders can amplify this.

The 2025 Consumer Reports investigation found plant-based powders had, on average, nine times more lead than dairy-based ones. Chocolate plant protein was the worst combination. None of the products tested were at levels causing immediate harm — the concern is chronic daily exposure over months and years.

The solution: third-party tested brands. Not "organic" — organic plant proteins actually had three times more lead than conventional in Clean Label Project testing. Organic certification doesn't protect against heavy metals. Third-party tested does.

Before anything else. Does this powder contain all 9 essential amino acids in meaningful amounts? Whey: yes, always. Single-source plant proteins (pea only, rice only, hemp only): usually not. Pea + rice blend with added BCAAs: yes, if optimized. Check the label explicitly for BCAA content or leucine fortification — don't assume.

This is non-negotiable for me. The certifications that mean something:

If a brand publishes its Certificate of Analysis (COA) online for every batch, that's a strong additional signal. If you can't find any testing data, that tells you something.

If you're in peri- or post-menopause, doing heavy training, or dealing with joint or skin concerns, 10–15g of hydrolyzed collagen peptides daily is worth adding — on top of, not instead of, your complete protein. Take it with vitamin C to support synthesis.

One I trust: Ancient + Brave True Collagen — grass-fed bovine, hydrolyzed peptides under 5000Da for maximum absorption, tasteless and odorless (dissolves into anything).

Most juice bars and smoothie chains use bulk protein powder with zero third-party testing. If they offer a vegan option, there's a strong chance it's not a complete protein. Ask — and if the person behind the counter doesn't know, that's your answer. Consider bringing your own when it matters to you.

If you're looking for options beyond Parsley's Rebuild, here are three that meet the criteria above — complete protein, independently tested, clean sourcing:

The goal: you don't need the fanciest powder on the market. You need a complete one, properly dosed, from a brand that tests what's in it.

Does this resonate? Hit reply — I'd love to know what powder you're currently using.

A good friend asked me to prescribe her a GLP-1 this week. And I did, without much hesitation.

She's a mom of three in her 40s — like me. Not meaningfully overweight, but she said: "Everyone is on them and everyone looks so good. I want to lose the 10 lbs I can't seem to shake before a big event in a few months."

I gave her the usual speech: prioritize protein, add weight training, get her dermatologist checks, run labs for thyroid, sex hormones, blood sugar, and heart health, do a full-body DEXA. Our team helped her get her first dose of Mounjaro/Zepbound within a couple of days.

Afterwards, I found myself wondering — was that the right thing to do?

She eats healthy-ish, travels a lot, drinks socially, works hard, and doesn't exercise as much as she'd like. Her diet, let's be honest, is more gluten-free pretzels than wild salmon. No judgment — just facts.

So the GLP-1 will probably help her lose the weight. But will she actually be healthier?

I also started wondering what we'll think about this moment in 20 years. Will we all be on GLP-1s? Will women everywhere be thin but frail, having lost bone and muscle mass over decades as a side effect? Will newer versions of these drugs be more fat-specific and protect us from that outcome? And what will we have lost — mentally, emotionally, physiologically — by outsourcing our metabolic health to a pill or a shot, instead of to exercise, sleep, and food?

I think about my sophomore year of college. I was at my thinnest — dangerously so — in the wake of my first major heartbreak, living on Diet Coke and crackers. I was also, by far, my most unhappy.

The things I do today to stay fit, at optimal fat, bone, and muscle mass — to be metabolically healthy — have side effects I wouldn't trade for anything. Exercise clears my head, moves my digestion, helps me sleep, and keeps anxiety at bay. Eating with a focus on protein, fiber, and healthy fats balances my sex hormones, keeps my cycles regular, gives me consistent energy, and keeps my skin and body feeling good. Sleep keeps my brain sharp, my mood stable, my focus clear.

All of these things serve my longevity and healthspan far beyond anything a number on the scale — or on the inside of my jeans — can account for.

The human body is miraculous. Still the most impressive machine ever built — more sophisticated in its intelligence than any AI large language model.

As we find new ways to make it look exactly how we want on the outside, let's not forget to pay attention to what's happening on the inside too.

Stay strong, stay curious, and breathe,

Robin

🎁 Forward this to the friend who is serious about protein but has never looked at the label on their powder.

The protein powder I use is Parsley's Rebuild — a pea and rice blend optimized with BCAAs to form a complete protein, with 26g per serving, a complete multivitamin built in, and gut-healing properties. It's what goes in my smoothie every morning. If you want help dialing in your total protein strategy, book a consult with a Parsley clinician.

As always, this newsletter is for informational and educational purposes only and is not intended as medical advice. Always consult your healthcare provider before making any health decisions or changes to your treatment plan.