The Definitive Guide to Tea

Tea can mean a lot of different plants. There’s maté, the bitter South American shrub steeped in boiling water to extract the caffeine-like compounds contained within. There’s rooibos, the “red tea” made from a polyphenol-rich bush native to South Africa. There’s coca, the South American plant also used to make cocaine. There are the unnamed wild bitter root and herb teas used by the Maasai, the evergreen tip teas used by American natives to obtain vitamin C, the nettleleaf teas used across Europe.

For today’s post, I’m focusing on the actual tea plant—Camellia sinensis. All of the classic teas come from the same basic plant; the differences lie in how they’re 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.

I’m also going to focus on the health benefits of tea, rather than get into the nitty gritty of tea grading, the endless bespoke varieties, the optimum temperature—tea expert stuff. I enjoy tea, but I’m not a connoisseur. I can tell you about the health effects, and I imagine that’s what most of you are here for anyway.

Types Of Tea

Even within “true tea,” there are multiple varieties.

White Tea

White tea is made from tea leaves that are very lightly processed without any oxidation. Studies show that it’s “lower” in antioxidants than green or oolong tea, but that doesn’t mean it’s “worse.”

White tea possesses compounds that inhibit the absorption and digestion of glucose, thereby lowering blood glucose levels.

White tea also shows a unique ability to fight amyloid plaque linked to Alzheimer’s disease (albeit in test tubes, not live people so far).

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, in general, the most antioxidant content—the catechins. In one study looking at the antioxidant content and effect of 30 different teas, the top 2 and 6 of the top 10 were green teas.

Most studies find that green tea is associated with the most health benefits among all the teas, but I take that with a grain of salt. For instance in this study, green tea was associated with better health outcomes than black tea among adults in the Mediterranean, but they failed to control for physical activity. Green tea drinkers had more physical activity, which the authors suggest is a benefit of green tea but I suggest is a feature of the “healthy user effect.” Green tea drinkers did more healthy stuff like exercise, while black tea drinkers were less likely.

There are consistent links between green tea and lower cognitive decline. We don’t see this as much in other teas (or coffee, for that matter).

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; in that same 30-tea antioxidant study, oolongs took 4 of the top 10 spots.

Black Tea

Black tea is fully-oxidized tea. It’s the highest in caffeine and rich in a class of antioxidants known as theaflavins.

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.

Pu-erh Tea

Pu-erh tea undergoes an additional level of microbial fermentation. It 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.

Animal studies show protective effects against metabolic syndrome, hyperglycemia, obesity, and fatty liver. It seems to reduce liver fat, but by a strange mechanism: by increasing de novo lipogenesis (fat creation) in the visceral adipose tissue. Rodents in the study lost weight but gained visceral fat.

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. First, there’s more L-theanine available. I’ve discussed the stress-reducing benefits of L-theanine before, but it’s also good against anxiety and pairs well with caffeine (more on that later). Plus, a 2003 study found that the epigallocatechin gallate (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.” My guess is that the increased bioavailability is explained by the fact that you’re consuming the powdered tea itself rather than steeping and discarding the leaves. 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, like fluoride content, less troublesome.

(Can you tell that matcha is my favorite?)

The Health Benefits Of Tea

In general, tea is a rich source of bioactive polyphenols with suspected health benefits. Some of the potential anti-cancer effects reported by the study:

Chronic obstructive lung disease (COPD): In Korea, drinking more than two cups a day of green tea was linked to lower rates of COPD.

Colon cancer: Among Korean patients who’d had colorectal adenomas (benign tumors) removed, taking green tea extract reduced the recurrence of them at one-year post surgery.

Prostate cancer: In Hong Kong, green tea consumption was linked to a reduced risk of prostate cancer. However, follow-up controlled trials in men with prostate cancer had mostly null results.

Skin cancer: Among whites, both caffeinated coffee and tea consumption were linked to protection against basal cell carcinoma (although coffee had the stronger relationship).

Most of the cancer studies in humans are merely observational. More interesting are some of the other effects.

Most tea varieties have mild anti-hyperglycemic effects, most likely caused by the ubiquity of substances that inhibit the effect of glucose digesting and absorbing enzymes. In other words, drinking some tea with your meal will generally reduce the amount of carbs you absorb.

Tea polyphenols are among the best at inducing a beneficial hormetic response—the one where your body responds to the presence of “toxins” by upregulating its own defense capabilities and triggering a net beneficial cascade of health effects. It’s up there with coffee, chocolate, and red wine. Green tea, for example, triggers the Nrf2 pathway, causing an increase in glutathione and other antioxidant pathways our bodies use to reduce oxidative stress and nullify reactive oxygen species.

The (Few) 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. For instance, women who consumed the most fluoridated water (and tea) during pregnancy give birth to kids with depressed IQs. 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. The lowest quality, cheapest brick tea is made from the oldest leaves and will be higher in fluoride.

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.

In Ireland, the only European country with legally mandated water fluoridation, the average fluoride content of brewed tea was 3.3 mg/L, with the highest levels hitting 6 mg/L. Based on Irish tea consumption, the authors suggest that “the majority of the population in Ireland are at risk of chronic fluoride intoxication.”

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.

For bagged tea, 5 minutes produced the most antioxidants.

For loose leaf tea, 60 minutes produced maximum extraction. However, the first 10-15 minutes were where the vast majority of antioxidants were obtained. Longer brew times extracted more, but the rate of extraction dropped off a cliff. 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: A recent study compared green and black tea brewed with three different waters: tap, bottled, and deionized. 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:

In the black tea study above, they used water at 80 degrees C or 176 degrees F. That’s well below boiling.

In the study comparing 30 varieties of green, black, oolong, white, and pu-erh teas, they used water at 98 degrees C or 208 degrees F. That’s almost boiling.

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 and throw a spoonful of matcha powder in with the grounds. I’ll 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. 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 new ways that takes the work out of the above. For those looking to get out the door quickly in the morning, tea in hand, check out the new Primal Kitchen® Matcha Keto Collagen Latte and Chai Keto Collagen Latte. I’m excited about them. 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, 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?

Thanks for reading, everyone. Take care!

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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