Resveratrol - The Basics

Before we get into how to choose a resveratrol supplement, we first need to go over some of the basics of where resveratrol comes from because it's relevant to understanding the science later on. 

Resveratrol belongs to a class of compounds called polyphenols. These are antioxidants that are partly responsible for the vibrant colors of plants and their fruits.

Resveratrol is most commonly associated with red wine and grapes. But it's actually found in over 70 species of plants and foods including berries, chocolate, and peanuts to name a few.(1)

Plants that are more "stressed", produce more resveratrol. It's a protective mechanism plants have evolved over millions of years to survive drought and damage from external organisms such as fungi. For example, grapes that are intentionally watered less to produce certain types of wine are known to contain higher amounts of resveratrol. 

When it comes to supplements, most brands on the market use Japanese knotweed extract (polygonum cuspidatum) which contains very high amounts of resveratrol. 

What is the best form of resveratrol to take (Cis vs Trans Resveratrol)?

One of the first questions people ask is what's the deal with cis and trans-resveratrol. 

Resveratrol comes in two forms, the cis form and the trans form, both of which refer to its chemical structure. 

Most, if not all of the supplements on the market use the trans form. This is simply because it's more biologically active and has been researched most extensively. It's not to say that cis resveratrol is useless. It's just not as active and therefore has relatively less impact. 

So when it comes to choosing a resveratrol supplement, take a closer look at the ingredients table and opt for trans-resveratrol. 

What is the purest form of resveratrol?

Now that we know that trans-resveratrol is the optimal form, now you'll want to look at the purity. Largely speaking, most of the supplements on the market contain one of two purities -  50% and 98%. 

So to put this into perspective, 1000mg of 50% purity resveratrol will contain 500mg of resveratrol. Whereas a 1000mg of 98% purity will contain 980mg of resveratrol.

And this is a crucial point to appreciate because supplements marketing "1000mg of resveratrol" with only 50% purity are not offering the same thing as a 1000mg dose with 98% purity. 

Don't get duped by the large dose numbers in marketing material. Take a closer look at the label and opt for 98% purity resveratrol. This way you can compare pricing and value for money much more easily. 

Choosing the best resveratrol dose per day

As with most dietary supplements, there is no official "recommended daily dose" per day of resveratrol. It's not a well-established and extensively researched supplement like, for example, vitamin C and D. 

That's why most supplements on the market base the dosage on available studies in humans. There are a handful of studies that have shown doses of around 500mg a day are well tolerated with no reported problems.(3)(4)

Higher doses of around 1000mg have been shown to inhibit certain liver enzymes which can have serious implications if you are taking certain medications. Hence speaking to your doctor before taking a supplement is essential.

It's very important to highlight that there are only a few studies on resveratrol dose. Nowhere near enough by scientific standards to recommend any real dose. So proceed with caution and consult your physician. 

Which form of resveratrol is absorbed the best?

You may have heard that resveratrol isn't absorbed so well from the gut. In fact, studies have shown that 75% of resveratrol is absorbed from oral supplements.(2)

In general, studies have shown that resveratrol may be better absorbed in the presence of fat. That means taking resveratrol with your breakfast or with a fat-containing food such as yogurt is ideal. 

On that note, you may have also come across different forms of resveratrol such as micronized and liposomal. These are more recent methods of delivering resveratrol by surrounding it in fat or making the supplement powder finer to increase surface area for absorption.

 At the time of writing, not much research has been done on other forms of resveratrol and the high purity powdered trans-resveratrol taken with some fat seems to do the trick anyway.

Other things to consider when choosing a resveratrol supplement

Aside from the three main considerations mentioned above, there are a few other things to be aware of that will impact the quality of your resveratrol supplement. 

Capsules 

Nowadays, most manufacturers are moving away from bovine-based gelatine capsules to vegetarian alternatives. They do the same job but ones simply plant-based, more sustainable, and avoids the use of animal products. 

Fillers and artificial flow agents

Fillers are commonly used to fill out the empty space in a capsule so as to make it look full. For example, a size 00 capsule can hold around 700mg of ingredients. But if a manufacturer only fills it with 350mg of resveratrol, the capsule will look half empty - which is not desirable. Instead of adding more resveratrol, which is expensive, cheap fillers are used which have no active biological role other than taking up empty space.

The other thing to be aware of is flow agents which are a standard part of the manufacturing process. These are added to the mix to allow the ingredients to flow through the machinery more efficiently and avoid clumping. The most common one being used is magnesium stearate. 

In large amounts, magnesium stearate acts as a laxative, and some people may have an intolerance to it. Therefore some manufacturers opt for all-natural alternatives such as rice flour.  

Manufacturing standards

You may want to check where your supplement is made and what manufacturing standards the makers adhere to. 

Always check for GMP certification (Good manufacturing practice) which means the manufacturer has been inspected by the regulatory body and compliance with health and safety regulations are met. 

3rd party testing

Some brands go the extra mile and pay for their product to be 3rd party tested. This means they send the finished product to an independent lab which will run it through an extra layer of testing to confirm that the supplement contains what it says it does

Are all resveratrol supplements the same?

You may have guessed by now that the answer to this question is no. Not all resveratrol supplements are the same. With so much variation in the market, it's no wonder people get confused. 

Aside from the form and purity of resveratrol, there are lots of other things to consider before choosing a resveratrol supplement. Always check the label to see the ingredients used and check out the company credentials to see where and how the supplement has been made. 

How to choose a resveratrol supplement - Final words

That brings us to the end of our look into how to choose a resveratrol supplement. 

As you've probably realized by now, there can be significant variation between products on the market. 

The main considerations are:

1. What's the purity - Ideally look for 98% trans-resveratrol
2. What's the dose - Although there's no official recommended dose, most studies use a daily dose of 500mg to 1g. 
3. Where and how is the supplement made - Check to see if it's made in a GMP certified facility, uses vegan capsules and natural flow agents
4. Is it 3rd party tested - Has the supplement been sent to an independent lab to check the dose and purity?