Choosing better carbohydrates in low-carb diets increases health outcomes

Choosing better carbohydrates in low-carb diets increases health outcomes

A new new study finds that swapping refined carbohydrates for whole foods in low-carb diets can significantly reduce inflammation and provide a clear path to better long-term health.

In a study recently published in the journalCurrent developments in nutritionResearchers examined associations between different low-carbohydrate diet (LCD) patterns and changes in oxidative stress and inflammatory biomarkers.

Chronic low-grade inflammation contributes to the development of various diseases, including type 2 diabetes, obesity, neurodegenerative diseases, cancers, and cardiovascular disease (CVD), particularly in older adults. LCDs have been studied for their potential to modulate inflammation and reduce the risk of chronic diseases. Carbohydrates from different sources can affect chronic inflammation differently.

Food Quality Rule: High-quality carbohydrates were defined as foods with at least 1g of fiber per 10g of carbohydrates, such as apples, broccoli and oats, as opposed to sugary grains or white bread.

High-carbohydrate (HQ) diets are characterized by increased consumption of non-starchy vegetables, whole grains, nuts, whole fruits, and legumes, which are associated with lower circulatory inflammatory biomarkers. Conversely, low-quality (LQ) carbohydrate diets are characterized by elevated intakes of sugar-sweetened beverages, refined grains, and sweet baked desserts, among others, and promote chronic inflammation through mechanisms like rapid blood sugar spikes (high glycemic impact), reduced fiber content, nutrient loss during refining, and the formation of inflammation-triggering compounds (advanced glycation end products).

Current evidence from observational studies on the associations between LCD patterns and inflammatory biomarkers has been primarily cross-sectional and limited to selected biomarkers. Additionally, many of these studies have not examined the quality of carbohydrates. Therefore, long-term associations between LCD patterns emphasizing carbohydrate quality and changes in oxidative stress and inflammatory biomarkers have not been adequately investigated. The key finding of this new research suggests that carbohydrate quality may be more important than just the amount of carbohydrates in reducing inflammation.

About the study

What people actually ate: Those who successfully cut low-quality carbohydrates ate more vegetables and nuts while cutting back on sweets and sodas without skimming on berries or whole grains.

The present study examined the long-term relationships between LCD scores (LCDS) and changes in oxidative stress and inflammatory biomarkers. Data were used from the Framingham Heart Study (FHS)-Pring cohort. The cohort included 2,225 participants with a mean baseline age of 59 (56% female, mean BMI 27.3 kg/m²). Participants underwent standard examinations every four years, including anthropometric, dietary and laboratory assessments. The study included data from the seventh (1998-2001) and eighth cycles (2005-08) with a median follow-up cycle of 6.7 years.

The food frequency questionnaire was used to assess food intake. Two LCDSS, HQ-LCDs and LQ-LCDs, were developed to evaluate carbohydrate quality in LCD samples. HQ-LCDS achieved the percentage of energy intake from LQ carbohydrates, while LQ-LCDs achieved it from HQ carbohydrates. Higher HQ-LCDs implied lower intake of LQ carbohydrates (while maintaining high-quality sources and replacing the low-quality carbohydrates with fat and protein), while higher LQ-LCDs represented lower intake of HQ-carbohydrates. The study also looked at a total low-carb diodes (T-LCDs) score that reflected lower total carbohydrate intake and higher total fat and protein, without separating carbohydrate quality. Nine biomarkers of oxidative stress and inflammation were assessed.

Biomarkers included C-reactive protein, interleukin-6, p-selectin, monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), lipoprotein phospholipase A2 (LPL-A2) and mass, osteoproteinin, Tumor necrosis factor receptor II factor and mass, tumor, tumor necrosis factor, and urinary opprotegin,. An oxidative stress and an inflammation score were estimated as the sum of the standardized rank scores of individual biomarkers (urine isoprostanes were excluded from this composite inflammation score due to a high number of missing observations at baseline). The primary outcome measured the change in this inflammation score over time.

Least-square mean change in the oxidative stress and inflammation score across LCDS quintiles was calculated using multivariable linear regression, adjusted for sex, age, energy intake, alcohol intake, body mass index (BMI), menopausal status, smoking status, physical activity, use of corticosteroids and non-steroid anti-inflammatory drugs, CVD history, and current diabetes, hypertension, or dyslipidemia and treatment for these. Sensitivity analyzes such as adjusting for waist circumference instead of BMI and excluding participants from hyperglycemia medication generally supported the main results for HQ-LCDs.

Results

Grain choice matters: The healthiest carb pattern included 3x more whole grains than refined grains, while the low-quality group did the opposite.

The highest quintiles of both LCDS included a higher proportion of women, diabetic subjects, tobacco users, and those with higher BMI. Total carbohydrate intake was approximately 19% lower in the highest quintiles of both LCDS and the lowest quintiles.

LQ carbohydrates were 17% lower in the highest HQ-LCDS quintile than in the lowest quintile, while HQ carbohydrates were 13% lower in the highest LQ-LCDS quintile than in the lowest quintile. There was an inverse association between HQ-LCDs and the change in oxidative stress and inflammation levels over the follow-up period. That is, oxidative stress and inflammation increased in subjects with the lowest HQ-LCDs (inflammatory score change: +0.28) and decreased in subjects with the highest HQ-LCDs (inflammatory score change: -0.31; Ptrend = 0.001 after full adjustment). The T-LCDs also showed a significant inverse association with inflammation and oxidative stress score (Q5 change: -0.32; Ptrend = 0.02), similar to that observed for HQ-LCDs, but slightly more modest than for HQ-LCDs.

QoL-LCDs had no significant association with the change in oxidative stress and inflammatory scores. In secondary analyses, HQ-LCDs was inversely associated with changes in LPL-A2 activity (a reduction of approximately 4% in the highest vs. lowest adherence groups; PTRend = 0.001) and ICAM-1 (a reduction of approximately 5%; Ptrend = 0.003). Meanwhile, LQ-LCDs was positively associated with changes in LPL-A2 mass (an increase of approximately 3%; PTRend = 0.04) and MCP-1 (an increase of approximately 1%; PTRend = 0.04), suggesting that higher adherence to LQ-LCDs was associated with increased inflammation.

Conclusions

Sugar Reality Check: Low-quality carb lovers consumed over 40% of their carbohydrates from added sugars, mostly in sodas and pastries, while high-quality eaters kept sugar under 10%.

Taken together, the results showed that LCD patterns that prioritize replacing low-quality carbohydrates (such as refined grains and added sugars) with high-quality carbohydrate sources (such as vegetables, whole grains), and with high-quality carbohydrate sources (such as vegetables, whole grains, legumes and legumes) or with healthy ones Fat sources with favorable changes in oxidative stress and a weight stress that with a lot, and with a lot. Point decrease in the composite value with high liabilities. In particular, HQ-LCDs showed a robust inverse association with the change in oxidative stress and inflammation levels, potentially reducing the risk of chronic diseases. Conversely, QoL-LCDs showed no significant association with the change in oxidative stress and inflammation levels. The study highlights that the approach to lowering carbohydrates, particularly by reducing low-quality species and maintaining high-quality ones, is a critical factor when considering the treatment of inflammation. This provides actionable insight: prioritizing whole grains, fruits, and vegetables over sugary snacks and refined grains within a low-carb dietary framework.

The authors acknowledged certain limitations inherent in the study, such as the reliance on self-reported dietary questionnaires and the fact that the study population was predominantly Caucasian American men and women, which may affect the generalizability of the results to other populations. Additionally, the study was unable to evaluate very low carbohydrate diets (e.g., less than 25% of energy from carbohydrates) due to a lack of such eaters in this particular cohort.

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