Chronic, low-grade inflammation can become a bridge to development of high blood pressure, heart disease, type 2 diabetes and cancer.
Is this just hype, or could one factor really pose risk to so much of what threatens health as we get older? If the risk it poses is real, how can you choose among all the anti-inflammatory diet and anti-inflammatory foods and supplements that appear in headlines everywhere?
These are the questions for today’s Smart Bytes®….
*Note: Originally published in 2017, this post has been updated in 2019 with new guidelines and results of new studies.
Inflammation can occur in the body in several forms:
- Acute inflammation occurs quickly following an injury such as a splinter in your finger or an infection. In a masterfully orchestrated defense, increased blood flow to the area brings white blood cells and body proteins that attack the intruder and heal injured tissue. As the threat is resolved, inflammation ends.
- Chronic inflammation involves an ongoing body defense response when harmful forces continue that can end up damaging blood vessels and other body tissues, accelerating development of long-term health problems.
Scientists measure a wide range of cell signaling proteins secreted by immune and other body cells as part of inflammation as they study how inflammation affects health and how it can be managed.
What is a CRP test?
A blood test known as CRP (C-reactive protein) is a common way to measure inflammation.
CRP is a marker protein produced in the liver that is used not only in research, but also in clinical care. “Regular” CRP tests (usually reported as milligrams per deciliter – mg/dl) can identify very high levels of inflammation like those seen in major infections or inflammatory diseases like rheumatoid arthritis and lupus. Regular CRP is not sensitive enough to pick up low-grade inflammation, however.
High-sensitivity CRP – hsCRP – detects low-grade inflammation that as a chronic condition is a marker of disease risk. For hsCRP, levels are reported as milligrams per liter (mg/L):
- Less than 1 mg/L is healthiest.
- Between 1 and 3 mg/L indicates intermediate risk.
- Above 3 mg/L indicates high risk.
- Values of hsCRP above 10 mg/L may signal an infection or other short-term cause of inflammation, so recommendations call for a test to be repeated in 2 to 3 weeks (with the lower value, not the average of the two tests, used to assess risk).
- Using hsCRP is most helpful for evaluating cardiovascular risk in people who have borderline results for other major risk factors, or in people with an LDL-cholesterol <130 mg/dl, according to the latest guidelines from the American Association of Clinical Endocrinologists (AACE) and American College of Endocrinology (ACE).
- An hsCRP of 2.0 mg/L or higher is identified as a risk-enhancing factor that can be used to guide decisions about preventive interventions for people at borderline or intermediate risk based on 10-year cardiovascular risk formulas, according to the 2019 guideline on primary prevention of cardiovascular disease from the American College of Cardiology (ACC) and American Heart Association (AHA).
To understand overall health risk, hsCRP needs to be interpreted in the context of other risk factors.
The midpoint (median) of hsCRP levels in the United States is close to 2 mg/L. About 1 in 4 people has levels exceeding 3 mg/L, according to a Journal of the American College of Cardiology review.1 in 4 Americans may have inflammation biomarker levels signaling high risk. Click To Tweet
What’s the Risk of Chronic Inflammation?
Heart disease is more than the traditional image of “clogged pipes”.
- Inflammation plays a role in development and destabilization of atherosclerotic plaque in blood vessels.
- Inflammation in blood vessels promotes “vascular remodeling” that leads to a stiffness in arteries. This can raise blood pressure and make high blood pressure less responsive to medications aimed at controlling it.
Cancer risk is also linked in multiple studies to elevated hsCRP. There’s solid evidence of reasons for such a link. But it’s important to check how studies adjust for other influences on cancer risk, since factors like smoking and obesity can also raise cancer risk outside of effects on inflammation.
- Over time, inflammation can damage DNA, beginning the process of cancer development.
- Inflammatory proteins also seem to promote cancer progression through several metabolic pathways.
Type 2 diabetes risk may also increase with elevated hsCRP. Chronic low-grade inflammation is considered a key factor leading to insulin resistance. And frequent high blood sugars can in turn contribute to oxidative stress that promotes more inflammation.
What are Anti-Inflammatory Foods?
Evidence is good that how you eat can help fight inflammation. But how to make sense of all the headlines announcing the “ultimate” or “best ever” anti-inflammatory food?
Don’t Confuse Lab vs. Human Studies
Human studies are expensive and complicated to conduct. Many of the studies that make headlines about anti-inflammatory choices are actually laboratory studies in which individual nutrients or compounds found in food are provided to animals or even added to isolated cells. This provides a good starting point for identifying potential ways to create an anti-inflammatory diet, but don’t make these studies the basis for your decisions about healthy eating.
- Many potentially anti-inflammatory compounds – like a wide range of different polyphenols in tea, berries, onions, soy, grapes and spices like turmeric and ginger – are broken down to smaller, more easily absorbed compounds before they leave the digestive tract and circulate in the blood. So testing the large compound is not testing what is actually reaching body cells.
- Whether nutrient or medicine, dose matters. Even when the “right” substance is tested and shows anti-inflammatory effects, that doesn’t tell us what amounts we’d need in our diets to get a benefit.
- When nutrients or compounds show anti-inflammatory effects in these studies, headlines — or our interpretation of them — can lead us to assume that “more is better”. Not true.
Even though excess amounts of highly reactive particles known as “free radicals” lead to oxidative stress that can increase inflammation, the goal for health is not to remove these particles completely. Research now shows that low levels of these free radicals trigger action from the body’s natural antioxidant defense system. This system consists of a variety of binding compounds and enzymes that convert free radicals to less reactive forms.Lab studies can show potential, but don’t make them the basis for planning an anti-inflammatory diet. Click To Tweet
An Arsenal of Anti-Inflammatory Foods
In previous Smart Bytes® we’ve looked through the lens of the Dietary Inflammatory Index (DII) to discuss the evidence on eating habits influencing chronic inflammation. The DII is a single score based on 45 different nutrients and compounds that research has individually suggested as potential influences (for good or for bad) on inflammation.
- In a national dietary survey of more than 5,000 adults, people in the top quarter of DII score (meaning more inflammatory) had 81% greater risk of a CRP level in the high-risk category of over 3.0 mg/L than people in the bottom quarter of scores (most anti-inflammatory diets). More inflammation-promoting diets as identified by DII scores have also been linked with greater risk of colorectal cancer, insulin resistance (the first step on the road to type 2 diabetes), and greater cancer and cardiovascular disease mortality.
Another tool for studying anti-inflammatory diets is the EDIP (Empirical Dietary Inflammatory Pattern) score. Researchers at Harvard developed the EDIP, based on 18 different food groups, half expected to be inflammatory foods and half to be anti-inflammatory foods.
- Highest scores on the food-based EDIP (more inflammatory) were associated with about 40 to 60 percent higher levels of hsCRP compared to lowest scores, even after adjusting for non-dietary factors known to affect inflammation. And highest scores on an index that combined the nutrient-focused DII and food-focused EDIP showed even greater elevations in hsCRP.
What Makes an Anti-Inflammatory Diet?
In addition to the observational studies using scores like the DII and EDIP, randomized controlled intervention trials also provide evidence about an anti-inflammatory diet.
- Adding the four components of the Portfolio Diet — viscous fiber, plant protein, nuts and sterols — to a diet low in saturated fat and relatively low in total fat reduced hsCRP by 32% compared to the same diet without those additions, according to an analysis combining seven different trials.
- Mediterranean-style eating patterns reduced hsCRP compared to people’s usual diets or diets after people were instructed on a low-fat or generally healthy diet, especially when analysis of 15 trials was limited to those that lasted at least three months.
The strongest foundation for creating an anti-inflammatory diet comes from the big picture of laboratory studies, observational studies that involve large groups of people, and intervention trials that can control for other potential influences.
Core Ingredients to Fight Inflammation
Although anti-inflammatory eating habits may differ somewhat between studies, they show several common threads. Create a personalized strategy with choices that fit individual preferences from a mix of these components:
- Foods rich in antioxidants and compounds that support the body’s antioxidant defenses ♦ Vegetables, fruits, whole grains, pulses (dried beans and lentils), nuts and seeds provide antioxidant nutrients and a wide range of polyphenols and other phytochemicals that seem to influence cell signaling and the complex body system of antioxidant enzymes and other elements. Coffee, tea, cocoa and extra virgin olive oil can also contribute compounds that seem to support antioxidant and anti-inflammatory defenses.
- Foods that support health-protective gut bacteria ♦ Certain vegetables, fruits, whole grains, pulses, nuts and seeds contain prebiotics, which means they nurture gut bacteria shown to promote health. Others provide compounds that gut bacteria convert to certain fatty acids and other substances that seem likely to be anti-inflammatory.
- Foods supplying omega-3 fatty acids that are used to produce anti-inflammatory compounds ♦ EPA and DHA are two omega-3 fatty acids found mainly in fish and algae that your body can convert to anti-inflammatory compounds. More research is needed on potential of ALA (the plant form of omega-3s) to counter inflammation, with promising results so far.
Look at your overall eating habits. What proportion of your food choices comes from foods like these?
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For a free tip sheet with more ideas on these 3 steps for a more anti-inflammatory diet, Click Here.
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Overall Day-to-Day Eating Habits as Key
The crucial question: If you make shifts to improve the healthfulness of your eating habits, can levels of inflammation change?
- Highest diet quality scores among women in the Nurses’ Health Study II linked to lower levels of hsCRP. And women whose diet quality improved the most over 13 years showed an 11 percent drop in hsCRP, whereas women whose diets improved least showed a 16 percent increase in the inflammatory marker.
- For each 10-point improvement in a healthful plant-based diet index — indicating increased consumption of whole grains, vegetables, fruits, pulses, nuts and healthy oils — hsCRP decreased about 18%. That was after adjusting for health and lifestyle factors that could influence inflammation. And even after adjusting for weight and weight change over 13 years, hsCRP still dropped significantly.
Bottom Line on Chronic Inflammation:
Chronic low-grade inflammation promotes development of heart disease, type 2 diabetes and at least some forms of cancer. Medications can tackle individual problems, like high blood pressure and cholesterol, and some can affect background pathways like insulin resistance and inflammation. But with all that success, to promote health in an even broader context, experts are consistent in emphasizing the need to start with healthy eating and lifestyle habits to address inflammation. Evidence shows that changing habits can change inflammation.
⇒ Would you like a free tip sheet – 3 Steps to a More Anti-Inflammatory Diet – with practical ideas based on today’s best evidence? Click Here to find out how to get it & receive Smart Bytes® by email.
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Credit: Blood test photo used with permission and purchased from 123rf.com, Image #39620579 by angellodeco