How Common Spices May Improve Gut, Brain, and Metabolic Health

Researchers have found growing evidence that everyday culinary spices may offer benefits far beyond flavor enhancement. Compounds found in spices such as cinnamon, turmeric, black pepper, oregano, and red pepper may influence blood sugar regulation, inflammation, cognitive function, and the composition of the gut microbiome.

The findings come from a review of published research, with particular emphasis on studies conducted at the University of California, Los Angeles (UCLA) Center for Human Nutrition. The review was published in the Nutrition Reviews.

Herbs and Spices: More Than Flavor Enhancers

Herbs and spices have been used for centuries across Mediterranean, Middle Eastern, and Asian cultures, serving not only as flavoring agents but also as preservatives and traditional remedies.

Herbs are typically derived from fresh leaves and flowers, while spices originate from roots, seeds, bark, stems, berries, and buds, most often in dried form. In addition to their culinary uses, many spices contain bioactive compounds with antioxidant and anti-inflammatory properties.

Several dietary guidelines encourage the use of herbs and spices as alternatives to salt. For example, the DASH diet developed by the National Institutes of Health recommends replacing sodium with herbs and spices to help support healthy blood pressure levels.

Researchers note that polyphenols and other plant compounds found in spices may help combat oxidative stress by neutralizing free radicals, potentially reducing the risk of chronic diseases associated with aging and metabolic dysfunction.

Review of Human and Laboratory Studies

Between 2010 and 2024, researchers at UCLA’s Center for Human Nutrition conducted eight clinical studies and 12 laboratory investigations examining individual spices and spice blends.

The review evaluated evidence on how these ingredients affect metabolism, inflammation, gut health, brain function, and disease-related biological pathways.

Cinnamon

Several clinical trials found that cinnamon supplementation reduced post-meal insulin and glucagon levels in both normal-weight and overweight individuals.

Cinnamon consumption was also associated with lower average blood glucose levels and changes in gut microbiome composition compared with placebo. However, researchers observed that some participants experienced temporary increases in blood sugar at certain time points, suggesting that cinnamon’s metabolic effects may be complex.

Additional evidence indicates that cinnamon may support healthy glucose regulation in both healthy individuals and people with type 2 diabetes.

Beyond metabolic effects, cinnamon has demonstrated anti-inflammatory, antioxidant, liver-protective, and neuroprotective properties. Researchers believe that cinnamaldehyde, one of its primary active compounds, plays a key role in these benefits.

Red Pepper

Capsaicin, the compound responsible for the heat of chili peppers, is known to stimulate thermogenesis but may cause gastrointestinal side effects at higher doses.

Researchers have therefore investigated non-pungent CH-19 sweet red peppers, which contain capsinoids such as dihydrocapsiate (DCT). These compounds appear capable of activating TRPV1 receptors in the gut, potentially increasing energy expenditure and fat metabolism without the discomfort associated with capsaicin.

A UCLA study reported that overweight and obese participants receiving DCT while following a calorie-restricted diet experienced increased post-meal energy expenditure. However, subsequent studies produced mixed results, with some showing only modest metabolic effects.

Turmeric

Research suggests that curcumin, turmeric’s main active compound, may offer a wide range of health benefits.

A UCLA study published in 2014 found that combining curcumin with arctigenin and epigallocatechin gallate (EGCG) enhanced anti-cancer activity in prostate and breast cancer cells compared with individual compounds alone.

Another study conducted in 2018 found that long-term supplementation with a highly bioavailable form of curcumin improved memory, attention, and mood in older adults. Brain imaging also revealed changes potentially associated with lower accumulation of amyloid and tau proteins.

Additional studies have shown that curcumin may reduce knee pain in osteoarthritis and improve cholesterol profiles in individuals with metabolic syndrome by increasing HDL cholesterol and reducing LDL cholesterol.

Scientists attribute these effects to curcumin’s antioxidant and anti-inflammatory activities, as well as its ability to influence cellular pathways involved in cancer development and cell survival.

Spice Blends and Gut Health

Studies suggest that spice mixtures containing black pepper, cayenne pepper, cinnamon, ginger, oregano, rosemary, and turmeric may promote the growth of beneficial gut bacteria, including lactobacilli and bifidobacteria, while suppressing certain potentially harmful microbes.

Research from UCLA also found that adding polyphenol-rich spices to meat before cooking significantly reduced markers of lipid oxidation.

Spice-derived polyphenols were additionally associated with lower levels of oxidative stress and improved endothelial function.

Among commonly studied spices, oregano demonstrated particularly strong antioxidant activity. Researchers also found that curcumin remains stable during cooking and that combining turmeric with black pepper may further enhance protection against lipid oxidation during food preparation.

Conclusions

The review highlights the growing body of evidence suggesting that herbs and spices may contribute to metabolic, gastrointestinal, cardiovascular, and cognitive health.

However, researchers caution that much remains unknown about how these effects translate to everyday dietary habits. Many laboratory studies use concentrations substantially higher than those typically consumed through food, and factors such as cooking methods, digestion, metabolism, and interactions with other foods may influence biological activity.

Despite these limitations, the authors conclude that greater attention to herbs and spices in nutrition research could help identify practical and accessible strategies for supporting long-term health and healthier eating patterns.

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