Holy Basil vs. Basil: Two Species, Two Different Jobs

Holy basil and basil are different species, and they taste different too. Holy basil, Ocimum tenuiflorum, is called tulsi in India and kaphrao in Thailand. It’s the hairier plant, with a peppery, clove-like smell built on different compounds, and it’s the herb a Thai cook wilts into phat kaphrao. “Basil” in most Western recipes means sweet basil, Ocimum basilicum, the softer, sweeter herb of pesto and tomato sauce. Check what you’re buying, too: in one US field trial, a seed lot sold as ‘Holy Sacred Red’ turned out to be sweet basil.¹

Side by side

For each herb in depth, see the holy basil and basil profiles.

How to tell them apart

Touch is the quickest test. Holy basil’s square stems are highly pubescent, meaning densely hairy, and they can be purplish. Its leaves are hairy too, densely covered in short hairs and especially hairy along the veins underneath. Sweet basil’s leaves are glossy, and its stems are smooth, or hairy only when young.

Leaf edges are a weaker clue than people think. A widely repeated claim says holy basil leaves are jagged like a saw blade and sweet basil’s are smooth. In fact, both sources on holy basil allow a range, from toothed to smooth-edged,³⁴ and Britannica says sweet basil leaves can be smooth or slightly toothed.⁵

Labels can mislead. Andy Ricker warns that the name “holy basil” sometimes ends up on purple-stemmed Thai or sweet basil, and that Indian grocers may sell true holy basil as tulsi.⁶ In the Purdue trial described below, a seed lot sold as ‘Holy Sacred Red’ turned out, by the researchers’ classification, to be O. basilicum, with a sweet-basil oil led by linalool.¹ So smell before you buy. True holy basil should be peppery and clove-like, not sweet or anise-like.

The difference in the oil

Purdue University researchers grew commercially available basils, holy basils included, in one field trial and distilled their oils the same way, so these rows compare like with like:¹

The holy basils share almost nothing with the sweet basils at the top of the list. A 2018 Chiang Mai University study of basils used as food in Thailand found the same split in a different setting. Both of its holy basils fell into a “spice-like” aroma group defined by methyl eugenol, β-caryophyllene and α-cubebene, while Thai basil, a form of sweet basil, was led by estragole.⁷ That study reported concentrations in µg/mL, not percentages, so its figures aren’t in the table above.

The flavor descriptions line up with the chemistry. Holy basil is peppery, with a distinctive aroma and a spicy bite that mixes clove, mint and basil. The leaves taste spicy and bitter, with notes of camphor, clove and cinnamon. Pailin Chongchitnant of Hot Thai Kitchen finds holy basil less floral and more peppery than Thai basil.⁸

Why “holy”

Holy basil is considered sacred in Hinduism and is widely used in Ayurvedic and folk medicine, often as an herbal tea. It’s revered in the Vaishnava tradition, and it’s common for Hindu families to grow it at home. None of the sources we found give sweet basil a comparable religious role.

Differences that change the dish

Holy basil goes in hot and late. In phat kaphrao, the stir-fry named for it, Ricker adds the leaves at the very end and stirs just until they wilt and turn very fragrant.⁶ It’s not only a Thai herb. It’s used as a culinary herb throughout Southeast Asia, and the leaves flavor salads and dishes with fruit, fish and chicken. You’ll also read that holy basil gives off more flavor when heated than sweet basil does. We didn’t find any source that tests that.

Sweet basil is the raw herb. Pesto, Caprese salad and torn leaves on pizza are sweet basil’s turf. Its Italian uses include pizzas, pasta, chicken and cheese dishes, and pesto. For cooked dishes, LSU AgCenter puts basil among the delicate herbs to add a minute or two before cooking ends.⁹

Tea. Holy basil is widely used as an herbal tea. None of the sources we reviewed describe sweet basil as a tea herb.

Can one stand in for the other?

Our holy basil substitutes page covers this swap in detail, and the advice below matches it.

• Sweet basil for holy basil: same amount (Attributed). Chongchitnant calls Italian basil her preferred substitute for holy basil and says it’s a closer match than Thai basil. Her pad kra pao recipe calls for 1 1/4 cups of holy basil or regular basil leaves, the same amount either way.⁸ Add it at the very end, just as you would holy basil. SheSimmers notes that if sweet basil is all you have, you can use it, but you should call the dish Pad Bai Horapha.¹⁰ You may see a more-for-less rule (1 1/2 times as much sweet basil). We didn’t find a source for it.
• Holy basil for sweet basil. In a cooked dish, start with about half the recipe’s basil and taste, since holy basil’s peppery, clove-like flavor is the stronger and more distinctive of the two. For pesto and other raw uses, we wouldn’t swap. It won’t taste like basil pesto.

Health claims and safety

Holy basil is sold widely as a supplement and tea, often with claims about blood pressure and cholesterol. The main systematic review, by Jamshidi and Cohen (2017), found 24 human studies covering metabolic disorders, cardiovascular disease, immunity and neurocognition. All reported favorable results with no significant adverse events. But the authors judged only a minority to be high quality and found insufficient evidence to recommend any specific tulsi formulation for any one condition.¹¹ The NIH’s National Center for Complementary and Integrative Health has no fact sheet on holy basil or basil.¹² We’re not claiming either herb treats or prevents any condition.

Both herbs contain alkenylbenzenes, the compound class regulators have looked at. Methyleugenol leads one of the holy basil oils above, and methylchavicol, also called estragole, shows up in sweet basil.¹³¹ Germany’s BfR says these compounds showed mutagenic and carcinogenic properties in animal studies, names basil-containing pesto among foods that may contain high amounts, and made no consumption recommendation for consumers in 2022.¹⁴ Holy basil isn’t on the FDA’s list of spices generally recognized as safe, which names sweet basil and bush basil.² We don’t draw any safety conclusion from that absence.

What isn’t known

• We didn’t find a study that has grown holy basil and sweet basil side by side since the 1999 Purdue trial, which used one seed lot per cultivar.¹
• No source tests whether holy basil gains flavor with heat, or compares how long either herb lasts in a hot dish.
• No survey measures how often “holy basil” on a label is really sweet or Thai basil.

Related

• Holy basil and basil profiles
• Holy basil substitutes and Thai basil vs. holy basil
• Basil vs. Thai basil, Genovese basil vs. sweet basil, lemon basil vs. basil
• Thai basil, Thai spices, how to store basil