Supplements and the evidence
Do Greens Powders Like AG1 Actually Work? What a Blood Test Shows
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed September 20266 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
QUICK ANSWER
A greens powder is food, not a fix. It can top up folate and magnesium if your diet is thin on vegetables. What it cannot do is tell you what was low to begin with. The only honest way to know whether yours did anything is to measure vitamin D, B12, folate and magnesium before and after.
Find out what is actually low. Build your test →As of September 2026. Greens powders are having another moment. AG1 launched AG1 Pro, a creatine-infused version of its Next Gen formula, in the summer of 2026, and it sold out almost immediately. The obvious follow-up never gets answered. Did the scoop change anything you can measure?
This is not a brand review. It is the shorter, more useful version: what these powders can move, which nutrients matter in the UK, and how to turn “I think I feel better” into a number.
1. What is actually in a greens powder?
Two different things, sold as one. The first is dried, milled plant matter: spirulina, kale, spinach, beetroot, mushrooms and algae. The second is a vitamin and mineral blend, added in a factory, much like a multivitamin.
That split matters more than the marketing suggests. The plant part gives you polyphenols and some folate, the B vitamin your body uses to build and repair cells. The vitamin blend is where nearly all the label numbers come from.
Here is the clearest example. No plant makes vitamin B12. The NHS is blunt about it:
“As vitamin B12 is not found naturally in foods such as fruit, vegetables and grains, vegans may not get enough of it.”NHS, Vitamins and minerals: B vitamins and folic acid
So if the tub lists B12, someone added it. The same goes for vitamin D. That is not a criticism. Fortification works. It just means the word “greens” on the front is doing very little of the nutritional work.
2. Which nutrients really run low in the UK?
A greens powder lists thirty or more ingredients. Most UK adults are not short of thirty things. Four come up again and again, and all four can be read from a blood sample.
Vitamin D
The one with real UK numbers behind it. An analysis of 449,943 UK Biobank participants aged 40 to 69 found 13.5% below 25 nmol/L. In winter that rose to 23.1%. The NHS says adults need 10 micrograms a day. Everyone “should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter”.
Vitamin B12
Adults aged 19 to 64 need about 1.5 micrograms a day, per the NHS. It comes from meat, fish, milk, cheese, eggs and fortified cereals. Eat little of those and this is your marker to watch.
Folate
Adults need 200 micrograms a day. The NHS names broccoli, sprouts, cabbage, kale, spinach, peas and chickpeas. This is where a greens powder has its most honest claim, because leafy greens really do carry it.
Magnesium
300mg a day for men aged 19 to 64, 270mg for women. The NHS adds a line worth reading twice: “You should be able to get all the magnesium you need by eating a varied and balanced diet.”
Notice what is missing from that list. Nobody in the UK is walking around short of the eighteen exotic mushroom extracts. The nutrients that matter are dull, cheap and easy to measure.
3. Why the label dose is not your blood level
A label tells you what went into the tub. Your blood tells you what ended up in you. Those are different numbers, for three reasons.
Dose. Compare the label against the NHS figures above before you assume you are covered. Some greens powders carry a full day of vitamin D. Others carry a token amount that will not shift a low reading in the middle of a British winter.
Starting point. A supplement cannot raise something that was never low. If your vitamin D was already comfortable, a daily scoop will not make it more comfortable. It will just be expensive.
You. Absorption varies with what else you eat, what medication you take and how your gut works. Two people on the same powder land in different places. That is why a test answers this and a review cannot.
4. How do you tell whether it worked?
Run it like a small experiment. Measure first. Take the powder daily for eight to twelve weeks. Measure again, at the same time of day, through the same laboratory. Anything shorter than eight weeks is too quick to read.
Helvy's Vitamins & Minerals panel (£159) is built for exactly this question. It reads vitamin D, B12, folate and magnesium alongside a full iron workup: iron, ferritin, transferrin, transferrin saturation and total iron binding capacity. Nine markers, one home finger-prick sample, processed by UKAS-accredited UK laboratories.
Want the wider picture from the same sample? The General Energy & Wellness panel (£149) covers vitamin D, B12 and magnesium too. It adds thyroid (TSH and free T4), cortisol, the full cholesterol breakdown and core liver and kidney markers. Seventeen in all.
5. When a greens powder is the wrong tool
Most people reach for one because they are tired. Worth saying plainly: persistent tiredness in the UK is far more often about low iron stores, an underactive thyroid or low vitamin D than a shortfall of kale. A greens powder does not touch the first two.
If tiredness is the real reason you are here, start with the energy and fatigue guides, and read up on what a full blood count covers. Those markers answer a different and usually more useful question.
None of this makes greens powders a scam. A scoop of dried vegetables with added vitamins is a reasonable thing to drink. The problem is buying one instead of finding out what is wrong. One costs you every month forever. The other costs you once and gives you an answer.
READY TO TEST?
Stop guessing what your scoop is doing
Helvy's Vitamins & Minerals panel reads vitamin D, B12, folate, magnesium and a full iron workup from one home finger-prick sample. Test before you start, test again twelve weeks later, and let the numbers settle the argument. Results in around 5 working days from UKAS-accredited UK laboratories.
See the Vitamins & Minerals panel6. Frequently asked questions
Do greens powders actually work?
It depends what you want them to do. For topping up folate and magnesium when your diet is light on vegetables, a greens powder is reasonable. As a fix for tiredness, low mood or poor sleep, there is no good evidence, and the usual causes sit outside what the powder contains. A blood test tells you which situation you are in.
Is AG1 worth the money?
That is a question about your results, not the brand. If your vitamin D, B12, folate and magnesium all read comfortably, any greens powder is an expensive habit with little to change. If one is low, a cheap single supplement at the NHS dose will usually shift it further than a broad blend. Measure first and the answer stops being opinion.
Can a greens powder replace vegetables?
No. Powders lose most of the fibre and bulk that make vegetables useful. The NHS advice has not changed: a varied and balanced diet should cover most of what you need. A powder is a supplement to that, not a swap for it.
How long before a greens powder shows up in a blood test?
Give it eight to twelve weeks. Vitamin D moves slowly, and a reading taken a fortnight in tells you almost nothing. Take both samples in the morning, through the same laboratory, and leave that day's dose off.
Which blood test should I get before starting one?
Look for vitamin D, B12, folate and magnesium as a minimum. Helvy reads all four in the Vitamins & Minerals panel, alongside a full iron workup. If tiredness is the real reason you are asking, General Energy & Wellness adds thyroid, cortisol and cholesterol.