The hs-CRP bands
| hs-CRP, mg/L | Band | Where the line comes from |
|---|---|---|
| Under 1.0 | Optimal | Guideline line, used as the Phoenix target. The CDC/AHA "lower risk" category. |
| 1.0 to under 2.0 | Monitor | Phoenix band. Inside the CDC/AHA "average risk" range of 1 to 3. Worth working on. |
| 2.0 or higher, on two tests | Talk to your doctor | Guideline line. The ACC/AHA risk-enhancer line. Phoenix asks for two tests because a single result swings. Bring it to your next appointment. It is not an emergency. |
| Above 10 | Repeat when you are well | Guideline rule. A result this high usually reflects an infection, an injury or another inflammation. Retest once you have recovered; if it stays above 10, your doctor looks for the cause. |
The line rule. "Under 1.0" excludes 1.0, and "2.0 or higher" includes 2.0. So 1.0 is Monitor and 2.0 is Talk to your doctor, once a second test confirms it.
Confidence in the optimal line: moderate. It is a guideline category. What Phoenix adds is the decision not to go stricter for carriers.
What does hs-CRP measure?
C-reactive protein is made by the liver when the body is inflamed. The high-sensitivity test (hs-CRP) reads the low levels that matter for long-term risk. Under 1, 1 to 3 and over 3 mg/L mark lower, average and higher heart risk, and hs-CRP predicts heart risk about as well as blood pressure or cholesterol (Ridker, 2016).
For a carrier, CRP is a window on chronic, low-grade inflammation: the slow-burning kind, not the spike from a cold.
What does APOE4 change about CRP?
APOE4 lowers your CRP, and that changes how to read it.
- Carriers run lower CRP at every age. The pattern held in four groups, from children of 9 to adults of 81, including 304,322 UK Biobank adults. It sits in the low range, under 5 mg/L (Wang, 2022).
- In the Framingham Offspring study, CRP rose with age in everyone, but less in carriers (Tao, 2018).
The danger for a carrier is CRP that stays clearly high:
- In 2,656 Framingham adults followed for 17 years, carriers whose CRP was 8 mg/L or higher on at least two occasions had a higher Alzheimer's rate (hazard ratio 4.70 within carriers), an earlier onset, and more shrinkage in the temporal lobe and hippocampus. People without APOE4 showed no such effect (Tao, 2018).
- In older Latino adults, carriers with higher CRP actually had lower rates of dementia and cognitive impairment (hazard ratio 0.60) (Haan, 2008).
- In 3,695 Finnish adults, hs-CRP did not predict cognition (Ekblad, 2017).
The Phoenix reading: the risk for a carrier is chronic, clearly raised CRP. It is not 0.6 against 0.4.
What do the guidelines say?
- CDC/AHA (2003): under 1.0 mg/L is lower risk, 1.0 to 3.0 is average, above 3.0 is higher. A result that stays above 10 calls for a search for another cause (Pearson, 2003).
- ACC/AHA (2018): hs-CRP of 2.0 mg/L or higher is a risk enhancer that can tip a statin decision (Grundy, 2018).
- The trial behind the 2.0 line: in JUPITER, 17,802 healthy adults with LDL-C under 130 mg/dL and hs-CRP of 2.0 or higher took rosuvastatin or placebo. Rosuvastatin cut major cardiovascular events by 44% (hazard ratio 0.56) (Ridker, 2008).
US guidelines use hs-CRP mainly when a statin decision is uncertain (Ridker, 2016). None of these lines was written for APOE4 carriers.
Why did Phoenix choose under 1.0, and not 0.5?
I chose under 1.0 mg/L, the CDC/AHA lower-risk line, the one the Phoenix app uses.
Not under 0.5. Some carrier advice, including guests on our own blog, says carriers should aim under 0.5. No study supports it, and APOE4 itself pushes CRP down (Wang, 2022). A carrier reaches 0.5 more easily than a non-carrier, without lower risk. The carrier data point at chronic CRP of 8 or more, not at the difference between 0.4 and 0.6 (Tao, 2018).
Two tests for the talk line. CRP swings. When 100 stable adults were tested 15 times over a year, 46% changed risk category at least once around the 2.0 line, and the typical month-to-month swing was 0.63 mg/L (Bogaty, 2013). One reading above 2.0 is a reason to retest, not a verdict.
How do you get an hs-CRP result you can trust?
Ask for "high-sensitivity CRP" (hs-CRP) by name. A standard CRP test is built to catch infections and is not designed to read the low range this page is about.
- Test when you are well. Not during or just after a cold, an infection, an injury or a flare of a joint or gut condition.
- Check the unit. Most labs report mg/L. Some report mg/dL, which is 10 times smaller: 1.0 mg/L is 0.10 mg/dL, and 2.0 mg/L is 0.20 mg/dL.
What moves hs-CRP?
Ranked by the size of the drop in the best trial data. Weight runs through most of them: semaglutide's CRP drop tracked its weight loss (Verma, 2023), and exercise lowered CRP most when weight fell too (Fedewa, 2017).
| Lever | What it did to hs-CRP | Who was studied | Source |
|---|---|---|---|
| Semaglutide 2.4 mg weekly (prescription) | 44% lower than placebo (48% in a second trial) | Adults with overweight, no diabetes | Verma, 2023 |
| Rosuvastatin 20 mg (prescription statin) | 37% lower, with LDL-C 50% lower | 17,802 healthy adults with hs-CRP of 2.0 or higher | Ridker, 2008 |
| Mediterranean diet | 0.98 mg/L lower | 17 trials, 2,300 people | Schwingshackl, 2014 |
| Weight loss | 0.13 mg/L lower for each kg lost (about 0.06 per kg in diet-and-exercise studies alone) | 33 studies | Selvin, 2007 |
| Regular exercise | A small drop (standardized effect 0.26; 0.19 without weight loss) | 83 trials, 3,769 people | Fedewa, 2017 |
| Quitting smoking | Slow: lower odds of a high CRP only after years (odds ratio 0.55 after more than 8 years) | 3,050 heavy smokers | Gallus, 2018 |
What this means in practice:
- Food and weight are the everyday levers. A Mediterranean diet cut CRP by about 1 mg/L across 17 trials (Schwingshackl, 2014). Losing 10 kg through diet and exercise is worth roughly 0.6 mg/L (Selvin, 2007).
- Exercise alone moves it a little. The effect was small across 83 trials (Fedewa, 2017), and a 35-trial analysis of adults with overweight found no clear change in CRP (Hejazi, 2023). Exercise for your insulin, your fitness and your brain; count any CRP drop as a bonus.
What Phoenix members use. Among Phoenix members who log their stack (counted 2 Oct 2026), omega-3 is the most logged supplement (184 members), ahead of a statin (80) and metformin, semaglutide or tirzepatide (38).
How often should you retest?
Guidelines use hs-CRP as a risk check, mainly when a statin decision is uncertain, rather than as a tracking test (Ridker, 2016). Two rules still apply:
- A result of 2.0 or higher: confirm it with a second test before you act on it. One reading swings too much to stand alone (Bogaty, 2013).
- A result above 10: repeat it once you are well. If it stays above 10, your doctor looks for the cause (Pearson, 2003).
Every time you test: test when you are well. After a change, retest with your next blood test and judge the trend over two or more results.
What Phoenix members do: 63 members have uploaded two or more hs-CRP results; for most, it never left the band it started in.
My numbers
I carry APOE4/4. In December 2024 my hs-CRP was under 0.5 mg/L, in the optimal band.
I have no hard-won CRP story to tell. A low CRP fits what the studies show about carriers, and it is why I will not use 0.5 as a carrier target: it would partly reward my genes, not my habits. I track CRP to catch the chronic rise that matters for a carrier, not to chase a smaller decimal. One carrier's result.
What Phoenix members' results show
Where members stand. Of 127 Phoenix members who uploaded an hs-CRP result (counted 2 Oct 2026), 108 (85%) are under 1.0 and 12 (9%) are in Monitor. The median is 0.3 mg/L, so more than half are already under 0.5. That is the member data behind refusing a 0.5 carrier target: most carriers would pass it without doing anything.
Most stay low. Of the 63 who uploaded two or more results, 56 (89%) stayed in the band they started in, and 51 of the 52 who started under 1.0 were still there at their latest test.
One member. An APOE4/4 woman in her 60s went from 1.2 to 0.2 mg/L in 139 days on omega-3: from Monitor to optimal, the largest hs-CRP drop in Release 001. Nothing else was recorded as starting in that window.
Members chose their own changes, and there is no placebo group. How Phoenix reads member data
When should you talk to your doctor?
Talk to your doctor if your hs-CRP is 2.0 mg/L or higher on two tests. That is the ACC/AHA risk-enhancer line, and it can change a statin decision.
If a result is above 10, repeat it when you are well. If it stays above 10, tell your doctor, who will look for the cause.
Between 1.0 and under 2.0, the result is worth working on. Read it next to your ApoB, your weight and your recent health.
If you take a statin, a GLP-1 medicine or an anti-inflammatory medicine, do not change it because of this page.