Heart and Soil vs Promix

Heart and Soil and Promix get compared for one simple reason: they all sell the idea of “clean,” grass-fed whey. On the surface, it all looks too similar. Minimal flavors. Premium pricing. Grass-fed claims. Minimal ingredients. Heavy emphasis on sourcing and quality.

But similar marketing doesn’t mean similar execution. This Heart and Soil vs Promix comparison exists to help you focus on which one truly supports its claims with transparency, testing, and measurable integrity so that you can make an informed choice.

If you’re deciding between these two because you care about protein quality, amino integrity, and what’s really in the scoop, this comparison will make the choice clearer.

For the full review of Heart and Soil, go here; for Promix Concentrate review, go here.

Heart and Soil vs Promix TL;DR

Quick Answer — Which Is Better: Heart and Soil or Promix?

Heart and Soil is the better protein if you value verified quality, transparent labeling, and lower risk around amino integrity and contaminants. Promix is cheaper per serving and shows bigger numbers on the label. Based on my long-form review of Promix Concentrate, there are red flags regarding protein quality. In this Heart and Soil vs Promix debate, who wins? Advertised quality versus opportunistic advertised labeling, at a lower price. If trust in verification matters more than saving a few dollars, Heart and Soil wins.

To support these unbiased comparisons, use my Amazon affiliate links for Heart and Soil Supplements and Promix concentrate.

How I Approach This Heart and Soil vs Promix Comparison

As a certified strength and conditioning specialist (NSCA) and sports nutrition specialist (CISSN), I evaluate supplements the same way every time: by what can be verified, not what sounds good on a pouch. This Heart and Soil vs Promix comparison is built directly from my original reviews. No brand partnerships. No influence.

I focus on protein integrity, testing transparency, sourcing honesty, amino acid disclosure, and real-world use. If a product delivers, I say so. If it relies on loopholes, I explain them. Whether it’s this Heart and Soil vs Promix comparison or any other head-to-head, the goal stays the same: help you understand exactly what you’re paying for and why, so you can feel confident in your choice.

Some links associated with this Heart and Soil vs Promix comparison may be affiliate links. If you choose to purchase through them, I may earn a small commission at no extra cost to you. That support keeps these reviews independent and unfiltered.

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Protein Transparency & Amino Integrity

On paper, both brands look strong. Promix lists 25 grams of protein per serving with an eye-popping 3.0 grams of leucine. Heart and Soil lists 24 grams of protein with 2.5 grams of leucine. The winner is Promix concentrate if you stopped reading there. 

The difference is how those brands compare against their peers. Heart and Soil’s protein math is on par for a concentrate. Promix protein totals,are surely eye-popping for a concentrate. Protein density favors Promix slightly at 83% versus Heart and Soil’s 80%, but density alone doesn’t confirm protein quality or completeness.

Heart and Soil’s numbers feels on par within grass-fed brands. Promix’s numbers are overly inflated for a whey protein concentrate. When it comes to transparency, Heart and Soil is easier to quantify and easier to trust.

Does Either Brand Show Signs of Amino Spiking?

This is where nuance matters.

Heart and Soil is not 3rd party verified for protein integrity. However, the protein yield, leucine percentage, and overall label math remain within a range consistent with intact whey protein. There are no obvious inflation signals in the traditional sense. However, the protein content is inflated when comparing whey fractions against NorCal Organic Whey and AGN Roots. 

Promix raises more flags. Higher leucine and BCAA numbers when compared to similar brands. Add in no verification increase uncertainty about what’s in the protein. Concerns of of nitrogen padding can’t be dismissed. That doesn’t prove spiking, but there are more questions left unanswered by Promix. 

Bottom line: Heart and Soil presents lower risk. Promix carries unanswered questions.

Third-Party Testing: Who’s Actually Verified?

Heart and Soil leans more heavily into verification. Testing focuses on safety and ingredient integrity, and results are presented in a way that allows consumers to assess risk with confidence.

Promix references third-party testing, but its scope focuses more on screening for safety than on full label validation, which affects how much you can trust its protein accuracy.

From a trust standpoint, Heart and Soil requires fewer leaps of faith.

Sourcing Transparency & Label Honesty

Both brands advertise self-proclaimed grass-fed whey. 

Heart and Soil takes a cautious approach, avoiding exaggerated sourcing claims and staying within what can be supported. Promix markets grass-fed sourcing more aggressively, but with fewer formal certifications backing it up.

In this comparison, Heart and Soil reads as reserved but credible. Promix reads as confident but harder to verify.

Ingredients & Sweeteners — Clean or Just “Clean Looking?”

Heart and Soil keeps the formula simple and functional. No artificial sweeteners. No unnecessary additives. The emphasis is on restraint rather than engineering flavor or texture.

Promix also keeps ingredients relatively minimal, but the formulation is more tuned toward taste and mouthfeel. It still looks clean, but it’s doing more behind the scenes to get there.

If your priority is simplicity, Heart and Soil is the cleaner formula. If you want a bit more palatability without going full dessert protein, Promix has the edge.

Heavy Metals & Prop 65 Concerns

Heart and Soil does not carry a Prop 65 warning and reports testing results that stay well below California thresholds.

Promix products carry a Prop 65 warning. That doesn’t automatically mean the product is unsafe, but it does change the risk profile, especially for daily use.

If heavy metal exposure is a deciding factor, Heart and Soil is the safer choice based on disclosed information.

Taste & Mixability — Which One Drinks Better?

Promix is easier to mix. However, in the taste department, it barely registers a blip. 

Heart and Soil is drinkable, but more utilitarian. Texture is thicker and less forgiving, especially with water. It feels like a functional protein, not a pleasure shake.

Winner on taste: Heart and Soil; Mixability: Promix.

Nutrition Facts & Protein Density Comparison

Promix delivers slightly more protein per serving and a marginally higher protein-by-weight percentage. When compared to other brands, mainly NorCal Organic Whey and AGN Roots, there are some red flags. Heart and Soil trails slightly in raw numbers but stays consistent across serving size, calories, and macronutrients.

The real difference isn’t the grams. It’s confidence in which protein do you believe more?.

Heart & Soil vs Promix: Which Grass-Fed Whey Protein Powder Is Better?
Key Differences & Comparison Metrics	Heart and Soil Protein Unflavored	%DV	Promix Concentrate Unflavored	%DV
Leucine	2.5g		3.0 grams
Leucine Percent	10.41%		12.0%
Total BCAAs	4.7g		5.9 grams
Protein Density %	80%		83%
Protein per Serving	24g	48%	25g	50%
Carbs per Serving	2g	1%	3g	1%
Fiber per Serving	0g	0%	0g	0%
Total Sugars	1g	—	1g	—
Calories	110 kcal		120 kcal
Serving Size	30g		30g
Number of Servings	30		38
Amazon Price(December 2025)	$73.00		$58.99
Price per Serving	$2.43		$1.69

Price per Serving — Which Is the Better Value?

Promix costs less per serving and offers more servings per container. On price alone, it wins.

Heart and Soil costs more, but that price includes cleaner testing outcomes, fewer labeling concerns, and a more conservative approach to protein claims.

Cheapest scoop: Promix. Best protein per verified dollar: Heart and Soil.

Who Each Brand Is Best For

Heart and Soil Is Best For:

• Lifters who prioritize transparency
• People who prefer conservative, verifiable protein claims
• Daily users who want lower risk heavy metal exposure

Promix Is Best For:

• Budget-conscious buyers for grass-fed whey
• People who value mixability
• Those less concerned with deep verification
• Users are comfortable trusting label claims at face value

To support these unbiased comparisons, use my Amazon affiliate links for Heart and Soil Supplements and Promix concentrate.

Final Verdict — Should You Buy Heart and Soil or Promix?

Technically, both proteins “work.” Here is the truth that neither wants to share: they work for different priorities.

Promix offers a better container; mixing in a shaker is easier, and it is priced lower per serving. Trade-off: concerns about amino integrity and Prop 65 warning stamped at the bottom of the bag. Heart and Soil costs more, and once you get past that top layer, it is surprisingly solid. You have to appreciate the level of transparency for Heart and Soil: stronger safety signals, cleaner documentation, and fewer unanswered questions.

If you want an advertised cheap grass-fed whey, Promix fits the bill. If you want the protein you can feel better about using every day, Heart and Soil is the winner in this matchup. 

To support these unbiased comparisons, use my Amazon affiliate links for Heart and Soil Supplements and Promix concentrate.

Heart and Soil vs Promix: Frequently Asked Questions