Raw white garlic shows promise in boosting heart health and reducing disease risks

By Hugo Francisco de SouzaReviewed by Susha Cheriyedath, M.Sc.Sep 8 2024

Find out why scientists believe a common kitchen staple might be the key to better heart health and disease prevention.

Study: Exploring the health benefits of raw white garlic consumption in humans: a mini review. Image Credit: New Africa / Shutterstock

In a recent review published in the journal Frontiers in Nutrition, researchers collated available data from two online scientific repositories to elucidate the potential health benefits of raw white garlic consumption on human well-being. Their literature search identified 22 relevant studies (12 clinical trials, including seven randomized controlled trials [RCTs], and 10 observational investigations).

Study findings suggest that raw white garlic consumption can significantly improve specific cardiometabolic biomarkers, such as lowering total/serum cholesterol, reducing triglyceride levels, and improving high-density lipoprotein (HDL) cholesterol. Additionally, it was found to enhance anthropometric measures like body mass index (BMI), waist-hip ratio, and fibrinolytic activity, which is critical for blood clot breakdown. Moreover, these improvements are linked to reducing the risk of chronic diseases such as cancers, prehypertension, diabetes (insulin homeostasis), and nonalcoholic fatty liver disease (NAFLD).

However, it is important to note that three of the clinical trials reviewed did not find significant health benefits associated with raw white garlic consumption. This highlights the variability in study outcomes and the need for a cautious interpretation of the results.

Unfortunately, most studies in the field suffer from the shared shortcoming of small sample sizes, insufficient follow-up periods, and predominantly Chinese study cohorts, restricting their generalizability. Specifically, nine of the ten observational studies were conducted in China, with five relying on the same dataset (Tianjin Chronic Low-grade Systemic Inflammation and Health [TCLSIH] cohort).

Background

Garlic (Allium sativum) is a bulbous flowering plant species closely related to onion, chives, and leek. The herb is inexpensive and easily accessible and has been used as a culinary flavor enhancer and medicinal supplement across global cultures.

Garlic has been shown to be rich in nutraceutical beneficial compounds, particularly sulfur, suggesting the health benefits of regular consumption.

Recent meta-analyses have validated these hypotheses, highlighting that garlic can substantially reduce lipid metrics (such as total cholesterol and triglycerides) with no adverse effects alongside red yeast and plant sterols.

Unfortunately, due to their frequent inclusion in dietary supplements, most research evaluating the impacts of garlic consumption on human health has focused on garlic extracts or aged black garlic. These garlic derivatives are obtained after significant industrial-grade processing, potentially altering their chemical composition and limiting health benefit extrapolations to fresh raw white garlic.

“Various drying methods employed in industry to prepare different garlic products result in decreased levels of bioactive constituents such as allicin, total phenols, and pyruvate compared to freshly harvested garlic. Instead, they contain various products resulting from allicin transformation. For example, sulfur compounds in fresh garlic may be nearly 1,000 times more potent antioxidants compared to those in aged garlic extract.”

Furthermore, processed garlic derivatives, such as those used in pharmaceutical additives and nutraceutical dietary supplements, are many times more expensive than raw white garlic and do not encapsulate the widespread traditional uses of the herb.

About the study

The present review aims to address these gaps in the literature and spurn further research efforts by collating and discussing the potential health benefits of raw white garlic consumption on human health from the limited number of clinical and observational studies conducted in this field.

Data for the review was obtained from the Scopus and PubMed electronic scientific repositories without publication date limits. Inclusion criteria restrict data collection to clinical trials and observational investigations comprising human cohorts, with studies on processed garlic (dried back garlic) or garlic extracts (garlic oils or juices) excluded.

Study findings

Publication title, abstract, and full-text screening revealed only 12 clinical trials (seven randomized controlled trials [RCTs]) and 10 observational studies fitting inclusion criteria. The observational studies comprised two prospective cohorts, four case-control cohorts, and four cross-sectional study designs. All observational studies and six of the 12 clinical trials included male and female participants.

Clinical trials had small cohort sizes, ranging from 5 to 49 participants, with ages spanning 17 to 70 years. Notably, eight of the 12 included trials reported beneficial health impacts following raw white garlic consumption, particularly on blood lipid levels, blood pressure (both systolic and diastolic), and antioxidant enzyme activity (e.g., catalase [CAT], superoxide dismutase [SOD], and glutathione peroxidase [GPx]). However, three clinical trials did not find significant associations, underscoring the mixed evidence.

Encouragingly, none of these trials reported adverse (side) effects of daily garlic consumption between 4g and 35g. However, the variability in dosage and study duration makes it difficult to draw firm conclusions.

Reported benefits included improved outcomes on blood lipid levels, blood pressure (BP; both systolic and diastolic), body mass index (BMI), fibrinolytic activity, waist-hip ratio, and enzymatic activity (catalase [CAT], superoxide dismutase [SOD], and glutathione peroxidase [GPx]). Encouragingly, none of these trials reported adverse (side) effects of daily garlic consumption between 4g and 35g.

Observational studies included between 865 and 28,958 participants per study. Study findings revealed that raw white garlic consumption was associated with reductions in the risks of chronic diseases, including cancers (especially liver and esophageal cancers),  prehypertension, depression (especially in women), and the recently diagnosed nonalcoholic fatty liver disease (NAFLD). Furthermore, frequent raw garlic consumption was observed to improve insulin homeostasis, handgrip strength, and thickened carotid intima-media thickness (cIMT).

However, the generalizability of these findings is severely limited by the fact that nine of the ten observational studies were conducted in China. Moreover, five of these studies used the same dataset, which raises concerns about data overlap.

Conclusions

The present study promotes the consumption of raw white garlic as a positive health behavior with no known adverse effects within normal human consumption ranges (<35 g/day). However, the limitations of current studies—particularly their restriction to Chinese populations, short study durations, and (in the case of clinical trials) insufficient sample sizes—underscore the need for additional research.

Future investigations should aim for larger, more demographically diverse sample cohorts to better understand the health benefits of this affordable and readily available ingredient. Only through such comprehensive research can raw white garlic be confidently recommended as a dietary supplement.