Metabolic syndrome affects 34 percent of all U.S. adults and 50 percent of Americans age 60 or older. (1) Because metabolic syndrome usually precedes type 2 diabetes and heart disease, reversing it is necessary for long-term health. Read on to find out how a Paleo diet can improve lipid markers and help patients with metabolic syndrome.
The definition of metabolic syndrome has changed over the years, but today it is generally recognized as a concurrence of at least three of the following five symptoms (2), each of which alone is a risk factor for diabetes and cardiovascular disease (3, 4, 5):
- large waist circumference
- high blood pressure (>130/85 mmHg)
- elevated fasting glucose (>100 mg/dL)
- elevated triglycerides (>150 mg/dL)
- low HDL cholesterol (<40mg/dL for men, <50mg/dL for women)
The underlying causes of metabolic syndrome are still debated. However, most medical professionals believe that insulin resistance and inflammation are the foundation of its development. (6, 7) Not so coincidentally, the modern Western diet, full of processed foods and omega-6 fatty acids from vegetable oils, is a huge contributor to both insulin resistance and inflammation. How, then, would an alternative diet, free of these inflammatory foods, compare with respect to metabolic syndrome markers?
Do high-carb-density foods in Western diets alter the gut and induce inflammation?
Although the markers of metabolic syndrome are rampant in modern society, traditional and tribal cultures are virtually free from these modern “diseases.” When transitioned to a Western diet, however, these populations quickly develop modern metabolic diseases. (8, 9, 10) By investigating various tribal and traditional diets and comparing them to modern “heart-healthy” diets, we may infer which factors are responsible for metabolic syndrome.
Some tribal cultures, such as the Kitavans, consume upwards of 60 to 70 percent of calories from carbohydrates, yet are free from modern disease. (11) Therefore, we know that high carbohydrate intake alone is not to blame for increased inflammation and metabolic syndrome found in the Western world, even though some argue otherwise.
Instead of carbohydrates themselves causing inflammation, it might be the source of carbohydrates that actually matters. For example, the Kitavan, Masai, Machiguenga, and !Kung tribes consume very little, if any, refined grains or processed sugars. (12, 13, 14, 15) A recent hypothesis proposed that these types of carbohydrates found in the modern diet induce inflammation through changes in the gut microbiome. (16) The article speculated that foods from traditional diets remain cellular during the cooking process and have lower carbohydrate density compared to acellular modern processed foods. In other words, modern food processing rips apart the cellular structure during high-temperature or high-pressure conditions such as those used for chemically extracted vegetable oils, modern grain milling, sugar refining, etc.
In a cellular carbohydrate-rich food (like a sweet potato), the upper gastrointestinal tract isn’t exposed to much of the “carbohydrate load,” as it is locked within cells until it is finally broken down later in the GI tract. In contrast, acellular refined foods begin digestion in the upper GI tract and the mouth. The unprecedented high-carb load is what changes the gut microbiome and subsequently increases inflammation. (16) I find this to be a compelling theory, but let’s also look at modern data that specifically compare traditional and modern diets.
Reverting to a Paleo diet
In a few studies over the past decade, randomized, controlled trials (RCTs) have compared tribal (or “paleolithic”/“hunter–gatherer”) diets to modern ones. As you would expect, the prototypical Paleo diet is completely devoid of refined sugars, processed flour, and many acellular foods. Most experimental Paleo diets excluded dairy and legumes, while favoring lean meats, fish, eggs, vegetables, fruits, nuts, and seeds. These studies demonstrate that a Paleo diet has a lot to offer those with perturbed lipid markers, metabolic syndrome, and diabetes.
The Paleo diet outperforms many standard “heart-healthy” diets.
Paleo diet benefits in patients with type 2 diabetes
A small 2015 RCT found that a Paleo diet improved fasting glucose, total cholesterol, and both HDL and LDL cholesterol in only 14 days, while a diet prescribed by the American Diabetes Association did not. (17) Both groups showed similar beneficial changes in body weight and fasting glucose levels. Interestingly, patients with the highest initial fasting glucose levels improved on the Paleo diet, but not on the control diet.
In a longer cross-over diet study, a Paleo diet outperformed the recommended diet for patients with type 2 diabetes. (18) Greater improvements were reported for triglycerides, diastolic blood pressure, body weight, waist circumference, and HDL cholesterol in the Paleo diet group.
In patients with both heart disease and type 2 diabetes or elevated glucose, a 12-week Paleo diet resulted in a greater reduction of waist circumference, fasting glucose levels, and two-hour plasma glucose levels compared to the Mediterranean diet. (19) Serum lipids and blood pressure improved similarly between the two groups.
Paleo diet benefits in patients with metabolic syndrome
Research shows that the Paleo diet can reverse markers of metabolic syndrome before type 2 diabetes or heart disease even develops. In 2014, a small pilot diet study reported that a Paleo diet lowered blood pressure, cholesterol, and triglycerides and increased HDL cholesterol more than the Dutch Health Council diet in patients diagnosed with metabolic syndrome. (20) At the conclusion of the short 14-day study, the number of patients with metabolic syndrome was actually reduced due to the Paleo diet intervention.
When a Paleo diet was followed for four months in patients with already elevated cholesterol, patients had better improvements in total cholesterol, LDL cholesterol, triglycerides, and HDL cholesterol compared to a diet prescribed by the American Heart Association. (21)
Over a two-year dietary RCT, the Paleo diet showed greater improvements in LDL, triglycerides, and total cholesterol compared to a low-fat diet at six months, but these differences were no longer detectable at two years aside from lowered triglycerides. (22) Similarly, in another two-year study, the Paleo diet outperformed the Nordic Nutrition Recommendations. While both diets boasted favorable effects for blood pressure, heart rate, and LDL cholesterol, the Paleo diet showed a greater decrease in triglycerides over time. (23)
Paleo diet benefits in people free from disease and metabolic syndrome
A small, short-term study in 2008 showed beneficial effects on body weight, waist circumference, and systolic BP after only three weeks. (24) At the start of the intervention, these patients had BMI, lipid markers, and glucose levels all within considered “normal” ranges.
Similarly, when a small group of non-obese yet sedentary people switched to a Paleo diet for 10 days after a three-day “ramp-up” diet, blood pressure, total cholesterol, LDL cholesterol, and triglycerides all improved on average. (25)
This growing collection of diet studies finally puts the Paleo diet in the right light. After even short-term dietary interventions, the Paleo diet continually outperformed other modern “healthy” diets in terms of reducing lipid and metabolic markers.
Limitations of current Paleo diet studies
RCTs comparing Paleo diets to others are limited in number and in scope. Several studies lasted merely weeks; few looked at time points beyond six months. Because preliminary data show advantageous effects on lipid markers and symptoms of metabolic syndrome, support for future studies with longer time points and larger group sizes is hopefully on the horizon.
Critics of the Paleo diet often point out how patients on an ad libitum Paleo diet usually consume fewer calories than patients on the control diets and end up losing more weight. They ask: Is it the fewer calories overall or the Paleo diet itself that is advantageous? It is a valid question.
However, Boer et. al. (20) accounted for this by providing approved snacks for the Paleo group to keep their weight similar to the control group. Even though the Paleo group still managed to lose more weight, they adjusted for this in their group comparison statistics. Similarly, Lindeberg et al. in 2007 found that glucose improvements were independent of waist circumference (19), and Pastore et al. in 2015 also accounted for weight loss differences between the two diets. (21) Even when weight loss is adjusted, the Paleo diets boast more benefits.
What’s more, is it a bad thing that people who eat Paleo diets naturally consume fewer calories? After all, that’s the “holy grail” of weight loss—spontaneous calorie restriction (i.e., eating less without trying) is far more effective for long-term weight loss than voluntary calorie restriction.
Others concerned with the Paleo diet worry about the relatively low calcium intake compared to other diets. (18, 20, 24, 26) However, two studies I discussed above showed that calcium urine output was decreased in those consuming a Paleo diet versus a control diet, indicating that although intake is lower, perhaps absorption is higher and calcium/magnesium balance is unaffected. (20, 17)
The Paleo cure
Prescribing a Paleo diet for your patients has little downside and has huge potential to improve metabolic syndrome, type 2 diabetes, and lipid markers. Even more motivating is that benefits can be detected in as little as two weeks, and Paleo dieters expressed a greater likelihood of adhering to their diet. (20) Alongside stress management, good sleep habits, and a healthy gut, your patients can begin their journey towards optimal health.
Now I’d like to hear from you. Have you seen any improvements in metabolic syndrome once patients switch to a Paleo diet in your practice? Were you aware of the growing literature studying the Paleo diet? Let us know in the comments!