Is black sesame the new matcha? This is how the claims stack up

Black sesame is the latest plant-based product to go viral, with its appealing colour and nutty taste.

Social media is full of claims these dark sesame seeds are better for you than the white ones. They're said to be better at reducing your blood sugar levels, risk of heart disease, and even reversing grey hair.

But is black sesame really the new matcha? You might remember this green tea was another plant-based, viral sensation with potential health benefits.

What is black sesame? What's in it?

Sesame seeds grow in white, yellow and black varieties. They've been used for centuries in traditional Asian cuisine.

Today, they're used in both savoury and sweet dishes, and are a good source of protein. Due to sesame's high fat content (about 50–64 per cent, see table below) it is also valued for its oil.

But there are differences between black and white sesame in some key nutrients.

Black sesame has higher levels of fat, protein and carbohydrate, but is also higher in energy (kilojoules). Vitamin and mineral levels are also generally higher in black sesame.

Sesame seeds are clearly highly nutritious products, but the amounts of nutrients in the table are for 100 grams, which is about two-thirds of a metric cup. Most of us would find it hard to eat this every day.

Typically sesame seeds are eaten as a garnish for stir-frys, curries and bread. In some cultures they are used more widely as a major ingredient in discretionary foods that also contain sugar and fat — such as halva, biscuits, tahini paste and sesame seed bars.

Sesame seeds also contain anti-nutrients. These are natural compounds, such as oxalic acid and phytic acid. These bind to minerals (iron, calcium and zinc) and reduce how much the body can absorb and use.

For most of us, eating foods in normal quantities that contain oxalate and phytic acid is not a concern. But if you have a known deficiency, increasing your intake of sesame seeds is not a good idea. If this applies to you, it is worth discussing with an accredited practising dietitian.

What about antioxidants?

Free radicals are formed naturally as a byproduct of all our usual bodily processes such as breathing and moving, as well as from UV (ultraviolet) light exposure, smoking, air pollutants and industrial chemicals. These can damage our proteins, cell membranes and DNA.

Sesame seeds contain antioxidants, chemicals that "mop up" these free radicals so they cannot cause damage.

One study found higher levels of phenols (a type of antioxidant) in black sesame seeds compared to white ones.

Black sesame also contains higher levels of lignans, an important group of phenols, than white sesame.

Cell and animal studies have looked at sesamin, the main type of lignan. These demonstrate its antioxidant properties, as well as cholesterol-lowering, blood pressure-reducing and anti-tumour effects.

But higher antioxidant levels don't always automatically translate into proven health benefits.

Is black sesame healthy?

BMI, blood pressure and cholesterol

A systematic review, which included the results of six studies with a total of 465 participants, looked into the health benefits of sesame. This included any type of sesame as either a seed, oil or capsule.

The authors reported a statistically significant decrease in BMI (body-mass index), blood pressure and cholesterol. Sesame doses were 0.06–35g/day over four to eight weeks. But not all these studies compared it to a placebo, were double-blinded (when neither participants nor researchers know who is receiving a particular treatment or placebo) and in some of the included studies medications were still being used.

Because of this the authors said the evidence was of low quality, and so could not make any health recommendations.

Only one study in the review looked at black sesame seed specifically. This looked at the effect of taking 2.52g a day as capsules compared with a placebo for four weeks. It showed a drop in systolic blood pressure (the top number in your blood pressure reading) from about 129 mmHg (a measure of blood pressure) to about 121 mmHg in people with prehypertension (blood pressure slightly higher than normal).

Grey hair

I could find no scientific studies that have looked at black sesame seeds and hair colour.

Similarly there is no current evidence any specific food or supplement can reverse grey hair.

Any risks?

Yes, about 0.1–0.9 per cent of the population around the world have a sesame allergy, a rate that appears to be rising.

Like all food allergies, the symptoms can be mild to severe. An anaphylactic response requires emergency medical treatment.

So what should I do?

The rise of black sesame does present a new ingredient you can enjoy in your cooking. If it doesn't appeal, regular sesame seeds are also an option.

Given the small amounts we typically eat, it won't make an overall difference to your health if you prefer black or white sesame seeds.

And as for black sesame to reverse grey hair, don't count on it.

Ensuring you have a wide and varied diet is the best way to ensure you get all the nutrients you need for optimal physical and mental health.

Evangeline Mantzioris is an accredited practising dietitian and program director of Nutrition and Food Sciences at Adelaide University. This article first appeared on The Conversation.