What human research says about their health benefits

Small ingredients, interesting science

Herbs and spices do much more than make food taste good. Many contain polyphenols, sulphur compounds and other plant chemicals that researchers are studying for their possible effects on blood sugar, blood fats and inflammation.

There is human research behind several familiar kitchen seasonings, including studies using ordinary culinary amounts. But the evidence needs to be described honestly: a change in a laboratory marker is not the same as proving that a food prevents a heart attack, diabetes or dementia. Some studies are small, short, or involve people who already have a health condition.

Ten seasonings worth knowing

1. Garlic (Allium sativum)

Garlic contains sulphur compounds, including allicin-related compounds formed when it is chopped or crushed. Human trials and reviews suggest garlic preparations can modestly improve blood pressure in some people, and may improve certain cholesterol measures. Results vary, and supplements are not equivalent to using garlic in food.

In the kitchen: Try it in beans, lentils, vegetable dishes, soups and sauces.

2. Ginger (Zingiber officinale)

Ginger contains gingerols and related compounds. Human evidence is strongest for helping with some forms of nausea. Clinical studies have also explored blood glucose, blood fats and inflammatory markers, with promising but not definitive results.

In the kitchen: Use fresh grated ginger in soups, curries, stir-fries or a simple infusion.

3. Turmeric (Curcuma longa)

Turmeric contains curcuminoids, including curcumin. Clinical trials have investigated joint symptoms, inflammatory markers and blood lipids. Some results are encouraging, but studies differ in dose and formulation. Curcumin supplements can interact with medicines and have occasionally been linked to liver injury; culinary turmeric is a different, much lower exposure.

In the kitchen: Add it to lentils, chickpeas, rice, soups and vegetable curries.

4. Cinnamon (Cinnamomum species)

Cinnamon has been studied for possible effects on blood glucose and blood lipids. Some trials report modest changes, particularly in people with diabetes or metabolic risk factors, but the overall evidence is mixed and it is not a substitute for diabetes treatment. For frequent use, Ceylon cinnamon generally contains much less coumarin than cassia cinnamon.

In the kitchen: Sprinkle a little on porridge, fruit or unsweetened drinks.

5. Fenugreek (Trigonella foenum-graecum)

Fenugreek seeds contain soluble fibre and other plant compounds. Human studies have examined blood glucose, insulin and cholesterol. The findings are promising in some groups, especially people with diabetes, but study quality and doses vary. Larger amounts may cause digestive symptoms and can interact with glucose-lowering medicines.

In the kitchen: Use a small amount of soaked or toasted seeds in lentils, curries and vegetable dishes.

6. Cardamom (Elettaria cardamomum)

Cardamom contains aromatic oils and polyphenols. A number of small clinical studies, often in people with metabolic conditions, have reported changes in inflammatory markers or blood pressure. This is interesting early evidence, not proof that cardamom prevents disease.

In the kitchen: Crush the pods and add them to tea, rice, stews or curries.

7. Coriander (Coriandrum sativum)

Both coriander leaves (cilantro) and seeds are used in cooking, although they have different flavours and chemical profiles. Clinical research on coriander is limited; some studies have explored body-weight and metabolic measures, but the evidence is not strong enough to claim a proven medical effect.

In the kitchen: Use the fresh leaves in salads, soups and Thai dishes; use the seeds in spice blends.

8. Cumin (Cuminum cyminum)

Cumin contains aromatic compounds such as cuminaldehyde. Small clinical trials have examined cholesterol, blood glucose and body-composition measures, with some positive findings. The number of studies is limited, so these results should be treated as preliminary.

In the kitchen: Toast the seeds briefly and add them to chickpeas, hummus, lentils or roasted vegetables.

9. Rosemary (Salvia rosmarinus)

Rosemary contains rosmarinic acid and diterpenes such as carnosic acid, which have antioxidant activity in laboratory research. Human evidence for specific health outcomes from normal culinary amounts is much thinner than the laboratory evidence. It is a flavourful way to add plant compounds without relying on salt.

In the kitchen: Add a sprig to roasted vegetables, potatoes, beans or soups.

10. Sage (Salvia officinalis)

Sage contains rosmarinic acid and other polyphenols. Small human studies have explored memory and cognitive performance, but the evidence remains preliminary and does not show that eating sage prevents dementia. Concentrated sage products are not the same as using the leaves in food.

In the kitchen: Use a little fresh or dried sage with beans, vegetables or sauces.

What is the strongest evidence?

A 2023 scoping review examined 142 human studies of culinary herbs and spices in relation to metabolic health. Cinnamon, fenugreek and ginger had the largest number of trials suggesting possible benefits for blood-glucose regulation. Cardamom showed potential for inflammatory markers, while cinnamon, ginger and turmeric showed potential for blood-lipid measures. The researchers also stressed that many studies involved people with type 2 diabetes or other existing metabolic conditions.

A separate 2021 systematic review of clinical trials on obesity-related measures reported positive findings in some studies of basil, cardamom, cinnamon, coriander, garlic, ginger, nigella and turmeric. These studies do not establish that adding any one seasoning will cause meaningful or lasting weight loss.

How to use herbs and spices sensibly

  • Use them regularly in meals for flavour and variety. There is no need to take concentrated extracts to enjoy their culinary value.
  • Think of them as part of an overall eating pattern rich in vegetables, beans, fruit, whole grains, nuts and seeds—not as medicine on their own.
  • More is not automatically better. Large supplemental doses can cause side effects or interact with medicines, including blood thinners and medicines for blood glucose or blood pressure.
  • If you take regular medication, have a medical condition, or are considering a concentrated herbal supplement, discuss it with a qualified healthcare professional.

The HealthyRetired takeaway

A well-stocked spice rack is a simple, inexpensive way to make healthy food more interesting. Garlic, ginger, turmeric, cinnamon and fenugreek have some of the more substantial human research among common seasonings, although the benefits are not guaranteed and are usually modest. Enjoy a variety of herbs and spices because they help make wholesome meals delicious—not because any single one is a miracle cure.

Sources and further reading

Editorial note: This article is educational and is not a diagnosis or a treatment plan. Consult a qualified healthcare professional before making major dietary changes or using herbal supplements, especially if you take medication.