Kristen Spang, MS RDN LD

A few of my go-to favorites

These are the things I actually find myself recommending over and over, whether we're working on getting more protein in, making meal prep less of a chore, or just making the kitchen a little easier to work in. Nothing here is a miracle product. They're just tools that make the everyday stuff more doable.


A quick note: some of the links below are affiliate links, which means I may earn a small commission if you buy through them, at no extra cost to you. I only include things I'd recommend regardless, and a commission never changes what I suggest to you. As an Amazon Associate I earn from qualifying purchases.

Supplements

Only where there’s a real gap — food first, always. I only link products with real third-party certification, so a few of these don’t have links yet.
Vitamin D3 + K2

One of the few most people genuinely benefit from, especially if you’re indoors most of the day — worth getting a level checked before you guess at a dose. On the K2 part, I’ll be straight with you: no trial has ever compared D3 plus K2 against D3 on its own, and the K2 trials that do exist used roughly four times the dose you’ll find in a retail bottle, with two of the three coming back negative. Plain D3 is cheaper and does the job. I link this one because Thorne’s is NSF Contents Certified, so someone outside the company has confirmed what’s actually in it. If you take warfarin, talk to your prescriber before you start — K2 works directly against it.

Magnesium glycinate

Glycinate gets recommended over citrate or malate because it’s supposed to absorb better and sit easier in your stomach. That’s a reasonable inference from how the molecule behaves, but nobody has run the head-to-head trial, so treat it as a preference rather than a fact. Where magnesium does have real evidence behind it is migraine prevention. For muscle cramps, the Cochrane review is negative — it just doesn’t work for that. This one is NSF Certified for Sport, which is the strictest certification in the supplement world, and it runs around seventeen dollars. Skip it if you have kidney disease.

Probiotic

Probiotics are strain-specific, not species-specific, which means “contains lactobacillus” tells you almost nothing. The one use with genuinely strong evidence is preventing C. diff diarrhea while you’re taking antibiotics — the Cochrane review there covers more than fifteen thousand people, and the rate drops from about four percent to one and a half. For IBS, bloating and general gut health, the gastroenterology guidelines actually recommend against them outside of a clinical trial. I link this one because its strain is the one with the antibiotic evidence behind it, though the honest caveat is that the products with real certification and the products with real strain evidence are mostly not the same products. If you’re immunocompromised, ask your doctor first.

Digestive enzymes

This is the one on the page I’d probably argue with you about. Outside of pancreatic insufficiency and lactose intolerance there’s no good evidence enzymes do much of anything, and the American Gastroenterological Association doesn’t recommend them for bloating. The trial everyone cites had twenty participants and an author employed by the manufacturer. Real enzyme replacement went prescription-only back in 2010 precisely because the over-the-counter versions weren’t reliable. It’s here because people ask me for it constantly, and if you’re going to buy one anyway, buy the one where NSF has confirmed the contents.

Omega-3 / fish oil

If you’re not eating fatty fish a couple times a week, this is a reasonable gap to fill — but I want to be honest about what it does and doesn’t do. The two biggest prevention trials, VITAL and ASCEND, together covering more than forty thousand people, both came back null for preventing heart attacks and strokes. The one trial that worked used a prescription drug at about four grams a day of pure EPA, which no retail capsule matches. Cochrane found no benefit for memory or thinking in healthy older adults. There’s also a real, dose-dependent signal for atrial fibrillation — roughly eleven percent higher risk per extra gram per day — so more is not better here. Where it does earn its place is high triglycerides. I link the Sport version specifically, because it’s the one NSF has certified; the regular bottle looks almost identical and isn’t. One thing certification doesn’t cover: NSF doesn’t test for oxidation, and about one in seven retail fish oils on US shelves exceeds peroxide limits. If the capsule tastes or smells fishy, that’s the tell.

Creatine monohydrate

One of the most studied supplements there is, and it’s cheap. Plain monohydrate is all you need — no fancy version required, and skip the gummies, which have documented problems holding their dose on the shelf. What it actually does: modestly more strength and lean mass when you’re lifting. Modest is the honest word — the effect size across trials in adults over fifty is small, and a 2025 trial found the quick early gain was mostly water weight. What it probably doesn’t do is any of the brain and mood things it’s being sold for right now. That entire research base is sixteen trials and fewer than five hundred people total, and the study that went viral gave fifteen people a single twenty-five gram dose during a night of no sleep, which is five times what anyone actually takes. Take it because you lift, not because an ad told you it would make you sharper. And the hair loss thing — a proper trial in 2025 measured hormones and actual hair and found nothing.

Fiber supplement

A bridge, not a fix. Helpful while we work on getting more fiber from actual food, not a reason to stop trying — and I mean that literally, because there is no trial showing a fiber supplement lowers your risk of heart disease, cancer or dying. All of that comes from studying people who eat fiber-rich food, and whole grains and legumes and produce bring potassium, magnesium and polyphenols along with the fiber. What psyllium specifically does have trial evidence for is narrower but still worth something: about eight to nine points off LDL, a meaningful drop in A1c, and better regularity. Note that “fiber” isn’t one thing — psyllium works because it’s viscous and doesn’t ferment much, which inulin and most prebiotic blends don’t do. I’ll be straight that this category barely has a certified option; this is the one I could verify, and one serving is a lighter psyllium dose than the trials used.

Digestive bitters

No link on this one, and that’s deliberate. The systematic review found bitters reduced food intake in only four of twelve studies, the appetite effects were basically a coin flip, and there was no effect at all on the gut hormones — GLP-1, CCK, PYY — that the marketing is built around. A lot of that research also delivered the bitters straight into the stomach through a tube, which is not what happens when you put a few drops on your tongue. On top of that, no bitters product carries real third-party certification. The biggest brand on Amazon markets itself as Certified Organic, which tells you how the plants were farmed and nothing at all about what ended up in the bottle.

Movement

A few things that make it easier to stay consistent
TheraBand resistance bands

The set physical therapists actually hand out, with graded resistance so you can move up as you get stronger. Latex, so skip these if you have an allergy.

Bowflex SelectTech 552 dumbbells

If you're building a home setup, one pair replaces a whole rack and covers five to fifty-two pounds. Not cheap, but it's the last set most people buy.

UREVO SpaceWalk E4W walking pad

The one I would point most people to, around $180. Independent testing measured it at 44 decibels at top speed, which is refrigerator-hum quiet, and it holds up to 265 pounds. Two things to know before you buy: there is no handrail, so skip it if your balance is at all shaky, and budget walking pads run hot, so think thirty to forty-five minute blocks rather than all afternoon. If you are shopping around, avoid Sperax. The CPSC warned in April about fall and fire hazards.

MERACH CV30 Pro vibration plate

I will be straight with you about this one. The research showing vibration helps bone used machines running around 30 hertz at a fraction of a millimeter. This runs 7 to 10 hertz at 11 millimeters, which is a different stimulus, not a smaller version of the same one. Consumer Reports looked at the category and found the health claims are not well supported. What it actually is: a low-impact way to stand and move that some people enjoy and stick with. If that is what gets you moving, good. Just do not buy it expecting bone density or lymphatic drainage.

Hyperwear Hyper Vest FIT weighted vest

Good for making a walk harder. I picked this one because it adjusts in half-pound steps and it is cut for a woman’s frame with no weight across the chest, which most vests get wrong. On bone: you will see this claim everywhere. The largest trial, 150 people over a year, found no bone benefit even at high doses, and most sites making that claim sell vests. Start around five percent of your body weight, and know that number is clinical opinion, not something a study has settled. If $115 is too much, a fixed-weight vest runs about $50, but you lose the ability to build up gradually.

The Cuff ankle weights

Useful for targeted leg work, the standing and floor exercises where you want a little resistance. I would steer you away from walking in them. Clinicians generally advise against it, and while that is reasoned opinion more than proven fact, your gait does measurably change once there is much weight at the ankle. These are what physical therapists actually use, and they are the only ones I have found in quarter-pound sizes, which matters if you are starting from a deconditioned place. They are sold individually, so order two.

Bala Bangles wrist weights

Honest answer: these are not a cardio tool, and swinging them on a walk is not doing much. Where they genuinely earn their place is when gripping a dumbbell is hard, whether that is arthritis, grip weakness, or recovering from something. Then you can do normal arm work without holding anything. For yoga, Pilates or barre they are nice. That is the use case.

Recovery

What’s actually worth taking after training, and two things that aren’t. Same rule as above — I only link what a certifier has verified.
Klean Casein

The reason this sits apart from the whey above is that casein digests slowly, which is why people take it before bed. I’ll be upfront that the pre-sleep timing angle is oversold. Protein before bed does raise overnight muscle protein synthesis — that part is real. But in the studies showing it, the pre-sleep groups also ate more total protein that day, so you can’t separate the timing from the dose. And a 2025 trial in untrained older adults, twelve weeks of supervised lifting, found no difference at all between taking it post-workout, before bed, or not at all, in people already getting enough protein. So take this because it’s a convenient way to hit your daily number when evenings are where you fall short. Not because the clock matters. NSF Certified for Sport.

Thorne Daily Electrolytes

The Nuun tablets in the hydration section are what I’d grab on a normal day. This is the one I’d point you to if you’re training in real heat, sweating heavily, or replacing more than you’re losing — it’s a fuller replacement rather than a flavor tablet, and it’s NSF Certified for Sport, which the Nuun isn’t. Nuun carries Informed Sport instead, which is legitimate third-party testing, just a step below the NSF mark. Most people don’t need either one on an ordinary day. Water and salt on your food covers it.

Tart cherry

No link, same reasoning as the bitters. Tart cherry is sold almost entirely on muscle soreness, and the 2026 meta-analysis — nineteen trials, three hundred eighty-five people — found no effect on soreness at any timepoint, and none on creatine kinase either. There’s a signal for strength recovery, but it swings wildly between studies and the authors themselves graded the certainty very low. The sleep research has the opposite problem: the wrist trackers say people sleep better, the people themselves say they don’t. What settles it for me is that the juice and concentrate used in the trials aren’t certified by anyone. The only certified tart cherry products are gummies at a fraction of the dose, and the “sleep” version gets its effect from three milligrams of added melatonin, not from the cherry.

BCAAs

Another deliberate one. BCAAs are three of the nine essential amino acids, and you need all nine present to actually build muscle protein — so taking three on their own gives you a smaller, shorter response than simply eating protein would. The review that laid this out is literally titled “myth or reality?” and lands on myth. If you’re already getting enough total protein, which is most people reading this, there’s nothing left for a BCAA powder to do. The whey and the casein above cover it, and cover it better.

Are you a fellow RD?

Most of this page is for clients. If you’re a dietitian, I keep a separate shelf — unbranded editable handouts with a practitioner page at the back you delete before it goes to the client, the spreadsheets I actually use, and a low FODMAP handout that’s free because I’d rather you see how I write before you spend anything.

Want to work together?

I see clients through Nourish, which means most insurance plans cover it — often at no cost to you. If you're not sure whether that includes you, just ask.