The Definitive Guide to Tea

Lots of steeped hot beverages call themselves tea that—surprise!—aren’t really types of tea at all. 

You’ve got your herbal teas made from flowers, herbs, and spices that can impart strong or subtle flavors and boast a variety of therapeutic benefits. There’s maté, the bitter South American shrub steeped in boiling water to extract caffeine-like compounds. There’s rooibos, the “red tea” made from a polyphenol-rich bush native to South Africa. There are the unnamed wild bitter root and herb teas of the Maasai, the evergreen tip teas used by American natives to obtain vitamin C, the nettle leaf teas enjoyed across Europe.

But real tea comes from one place: the Camellia sinensis plant. Technically speaking, if it ain’t Camellia, it ain’t tea. 

Even within “true tea,” there are multiple varieties. Today I’m going to briefly distinguish between the types of tea. Once you open the door to the world of tea, you discover there are endless bespoke varieties, not to mention exacting specifications around tea grading, optimum brewing techniques, and serving conventions—which is all very interesting, but mostly I’ll focus on the health benefits here.

Types of Tea

The differences here boil down (no pun intended) to how tea leaves are processed after harvest. 

Most tea undergoes controlled oxidation to develop flavor and different bioactive compounds. The more oxidized, the darker the tea; the less oxidized, the lighter. Besides color and appearance, teas differ in terms of flavor and caffeine content. 

I’m not going to try to tell you which tea is “best.” All teas are rich in polyphenols—plant compounds that act as antioxidants and are largely responsible for the health benefits ascribed to tea consumption. Green and white teas tend to have the highest polyphenol concentration, so they are arguably the “healthiest,” but it’s all a matter of degree. They also, with the exception of pu-erh teas, all contain L-theanine, a nifty little amino acid that helps you mellow out.

You can’t really go wrong. 

White tea

White tea is made from young tea leaves that are very lightly processed without any oxidation. White teas have a light color and delicate flavor, but don’t let this unassuming beverage fool you. White tea contains high concentration of polyphenols, particularly a class called catechins. Catechins, especially EGCG, are responsible for the much-lauded health benefits ascribed to green tea. White tea, at least according to some reports, contains even more catechins than green.1

Some of the noteworthy findings related to white tea:

White tea possesses compounds that inhibit the absorption and digestion of glucose, thereby lowering blood glucose levels.2 In prediabetic rats, white tea consumption improves glucose tolerance and protects against insulin resistance.3

White tea also shows a particular ability to fight amyloid plaque linked to Alzheimer’s disease (albeit in test tubes).4

In animal and cell models, white tea displays anti-cancer properties. Researchers have found that compounds in white tea induce apoptosis (cell death) in lung cancer cells5 and can inhibit mutagens, which cause genetic mutations that can lead to cancer.6 

Green tea

In Japan, green tea is lightly steamed. In China, it’s quickly toasted under dry heat. The result with each is light oxidation. It has a grassy flavor and high antioxidant content (particularly EGCG, EGC, ECG, and EC).

In the court of public opinion, and often in medical circles as well, green tea is considered the most beneficial; but what’s true for green is almost certainly true for white (and vice versa), if not always the other varieties. 

That said, green tea certainly has a lot going for it. 

There are consistent links between green tea and lower cognitive decline. We don’t see this as much in other teas.7 8 The more green tea you drink, the stronger this effect seems to be.9

Observational research also shows an inverse relationship between green tea consumption and certain types of cancer10 11 and high blood pressure,12 but these types of studies can’t establish a causal relationship.

Black tea

Black tea is fully oxidized. English Breakfast, Irish Breakfast, Earl Grey, Assam tea, and many other common teas are black varieties. Chai, milk tea, and kombucha are usually, but not always, made with black tea.

The primary polyphenol in black tea is a class called theaflavins. Theaflavins can act on signaling pathways that regulate cancer growth.13 14

Randomized controlled trials also found that black tea can lower LDL.15 Theaflavins in the 50-100 mg range (4-8 cups of black tea) reduced body fat and increased muscle mass in Japanese women, while green tea catechins had no effect.16

Oolong tea

Oolong is “halfway between” green tea and black tea: more heavily oxidized than green, less oxidized than black. Oolong also ranks highly for antioxidant content, including the same polyphenols that make green and white so potent. In a study of the antioxidant content of 30 teas, oolongs took four of the top ten spots.17

In rodents, oolong changes the composition of the gut microbiome, increasing the prevalence of beneficial bacteria and decreasing the numbers of unwanted microbes.18 19 It shows some potential to prevent obesity in mice, as well, although I wouldn’t put too much stock in oolong being the next big weight loss drug for humans.20 

Pu-erh tea

Pu-erh tea undergoes an additional level of microbial fermentation, which develops intense flavors and unique bioactive compounds.

For example, pu-erh contains alpha-amylase and alpha-glucosidase inhibitors that reduce the absorption of dietary glucose and lower blood glucose levels, particularly after eating.21

Animal studies show protective effects of pu-erh and its components against metabolic syndrome, hyperglycemia, obesity, and fatty liver.22 23 

Matcha tea

Matcha green tea is made from powdered, shade-grown tea leaves. Well, “shade-finished” might be a more accurate descriptor; a few weeks before the harvest, matcha-designated tea plants are covered with shade. This slows the growth, sweetens and deepens the flavor, and increases the amino acid content of the leaves (specifically L-theanine).

Pulverizing the tea leaves into a powder increases the surface area and makes for a stronger, more potent brew. Plus, when you drink matcha, you’re consuming the leaves and all their polyphenols and amino acids themselves. The powder doesn’t get strained out like normal green tea leaves. This seems to increase the antioxidant activity. A 2003 study found that the EGCG was 137 times more bioavailable in matcha than a traditional leaf-based green tea, and more than three times as bioavailable as the “largest literature value of other green teas.”24 

Another advantage of matcha is that because it’s so potent, you need much less of it, rendering any of the potential downsides of tea, discussed below, less troublesome.

(Can you tell that matcha is my favorite?)

Caffeine in Tea

Although it contains less caffeine than a typical cup of coffee, all true tea varieties are naturally caffeinated. Pinning down the exact levels of caffeine is more or less impossible, though. The amount of caffeine in your brew is a factor of type, age of the leaves, harvesting method, and brewing (time, water temperature). 

As a general rule, darker teas—black, pu-erh, oolong—contain more caffeine than green or white. Individuals who are particularly sensitive to caffeine or who want to give it up for whatever reason will want to stick to decaf or herbal teas.

A Couple Negatives To Look Out For…


I’ve covered fluoride before, and I’m still not sure of it. It seems to have some benefits for topical application to teeth, but systemic ingestion poses problems.

Tea is very high in fluoride. The plant itself is quite good at yanking fluoride from the soil, and soil fluoride in tea-producing countries is on the rise due to industrial pollution. High-quality tea made from younger leaves is more likely to be lower in fluoride since the plant won’t have had as much time to deposit soil fluoride into the leaves. White tea is generally low in fluoride, since the leaves are picked when still very young. Green, oolong, and black tea leaves all stay on the plant long enough to pick up measurable levels of fluoride. The lowest quality, cheapest black tea is made from the oldest leaves and will be higher in fluoride.

Organic Japanese-grown matcha green tea is a good option for fluoride minimization, as Japanese soil tends to be quite low in fluoride.


If you use plastic tea bags, your tea will be full of microplastics. Stick to loose leaf or paper tea bags.

How to Brew It

Okay, so how should you brew your tea?

Duration: If you’re trying to maximize antioxidant extraction, longer is better.

In one study of bagged and loose leaf black tea, longer brew times extracted more antioxidants.25 For bagged tea, 5 minutes produced the most antioxidants. For loose leaf tea, 60 minutes produced maximum extraction. However, the first 10 to 15 minutes were where the vast majority of antioxidants were obtained. 

The difference between 15 minutes of brewing and 60 minutes of brewing probably isn’t enough to justify waiting an hour for your tea.

Water choice: One study compared green and black tea brewed with three different waters: tap, bottled, and deionized.26 Tap water with higher levels of minerals produced the best tasting tea with the lowest amount of antioxidants. Bottled and deionized water with lower levels of minerals extracted the most bitter compounds, leading to a higher antioxidant level but harsher taste.

Water temperature: I’ve read and heard a lot of different “rules” for brewing tea. Some say to never boil the water. Others say the opposite. All I know is that I’ve never noticed a big difference—but I’m no expert. What I do know is that both low and higher water temperatures seem to extract and preserve a good amount of antioxidant content:

A Few Ways to Enjoy It

Collagen matcha latte: Read this post for directions.

Coffee matcha: Sometimes I’ll make a batch of French press coffee, throw a spoonful of matcha powder in with the grounds, and add some hot heavy cream to the brew. This is a great way to get caffeine and L-theanine at once, a synergistic combo shown to improve cognitive performance.27 Many find that theanine takes the jitter away from the caffeine buzz.

Creamy turmeric tea: Read this post, and add some black tea.

And… I’ve got a couple products that take the work out of the above. For those looking to get out the door quickly in the morning, tea in hand, check out the Primal Kitchen® Matcha Keto Collagen Latte and Chai Keto Collagen Latte. Let me know what you think.

Summing It Up

Like everything else, tea is no super-substance that will save you from cancer, diabetes, and obesity. But it’s a drink that’s consistently (and sometimes causally) associated with better overall health, likely due in no small part to its antioxidant content. It has a long tradition of usage and can complement an otherwise healthy diet and lifestyle. All teas appear to have some benefits, so drink what you like most.

What kind of tea do you drink? How do you make it? How do you take it? 

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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