Blackstrap Molasses

Blackstrap molasses is the thick, dark, bitter-edged syrup left after sugar-cane juice has been boiled and spun for its sugar three times. A tablespoon still carries roughly 9 to 15 grams of sugar, along with real amounts of calcium, magnesium, potassium, manganese and — depending on the jar — iron: a mineral-rich sugar, not a supplement. The popular claims that it reverses grey hair or “stops insulin resistance almost immediately” rest on 1940s rat experiments, a rare deficiency and single-meal studies of molasses extracts, not on any trial of blackstrap itself.

Table of Contents

  1. What Blackstrap Molasses Is
  2. History and Traditional Use
  3. What Is Actually in a Tablespoon
  4. Grey Hair, Copper and the PABA Era
  5. Blood Sugar and the Insulin-Resistance Claim
  6. Iron and Iron-Deficiency Anemia
  7. Constipation: One Trial in Children
  8. How People Use It
  9. Myths and Overclaims
  10. Safety and Who Should Be Careful
  11. Key Research Papers
  12. Connections
  13. Featured Videos

What Blackstrap Molasses Is

Molasses is what is left when sugar is taken out of sugar-cane juice. At the mill, cane is crushed and its juice is cleaned and boiled down until it is thick enough for sugar crystals to form. A centrifuge then spins the crystals out, and the dark syrup that drains away is molasses. Because that syrup still holds dissolved sugar, the mill boils and spins it again — and again. The syrup from the first round is light molasses, the sweetest and mildest; the second round gives dark molasses; the syrup left after the third round, from which no more sugar can be profitably crystallized, is blackstrap, also called final molasses.

Each round removes more sucrose and leaves everything else behind in a smaller volume: the cane's minerals, its plant polyphenols, and the brown, bitter-edged compounds that form when sugars are heated. That is why blackstrap is darker, thicker, less sweet and more mineral-rich than the molasses in most cookie recipes, and why many people find its first taste bittersweet, earthy and faintly mineral rather than sweet.

A few label terms are worth knowing:

Most of the world's final molasses never reaches a kitchen. It is fed to livestock and fermented into baker's yeast, rum and industrial alcohol; the blackstrap sold in a jar is a small side-stream of an industrial by-product.

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History and Traditional Use

The word molasses reached English through Portuguese (melaço), from the Latin mel, honey. In the American colonies molasses was the everyday sweetener — cheaper than white sugar, it went into brown bread, baked beans, puddings and gingerbread — and it stayed a staple of American kitchens until refined white sugar became cheap in the late nineteenth century.

It also has a dark economic history. Molasses from Caribbean sugar plantations, worked by enslaved Africans, was shipped to New England and distilled into rum, one strand of the Atlantic trade that carried enslaved people across the ocean. Britain's Molasses Act of 1733 taxed molasses the colonies bought from French and other foreign islands; the tax was widely evaded, and the Sugar Act of 1764 that replaced it became one of the colonial grievances on the road to the American Revolution. In January 1919 a storage tank in Boston's North End, full of molasses waiting to be fermented into industrial alcohol, burst; the wave killed 21 people, and the Great Molasses Flood is still one of the strangest industrial disasters in American history.

Blackstrap's reputation as a health food is much newer. In the 1930s and 1940s, rats and mice fed purified diets lacking certain B-group factors — pantothenic acid and para-aminobenzoic acid (PABA) among them — grew grey fur, and adding the missing factor back sometimes restored the color (see our PABA page). Popular diet books and health columns of the 1940s and 1950s turned this into a promise for people, and blackstrap molasses — a cheap food with copper, iron and small amounts of B vitamins — was promoted as a “wonder food”, not least as a way to bring color back to grey hair. That idea, and the older habit of a daily spoonful for low iron, are still circulating, now on video. The sections below weigh both.

Traditional medicine systems use sugar-cane products too. Persian medicine used several sugar-cane preparations, blackstrap molasses among them, for constipation in children, which is what prompted the one modern trial of blackstrap described below. Ayurvedic practice prescribes formulations containing sugar-cane derivatives for pandu, a condition resembling iron-deficiency anemia. Traditional use tells you what people tried; it does not tell you what works.

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What Is Actually in a Tablespoon

Two sets of numbers exist, and it helps to know which is which. USDA FoodData Central has a laboratory-analyzed entry for molasses (FDC ID 168820, SR Legacy database) that does not say which grade was tested. It has no analyzed entry for blackstrap: the blackstrap records in FoodData Central are manufacturers' nutrition labels, which list only a few minerals.

USDA's analyzed molasses, per tablespoon (20 g)

What blackstrap labels say, per tablespoon

Nine blackstrap nutrition labels in FoodData Central's branded-foods data give, per tablespoon:

The spread is the story. Blackstrap is an industrial by-product, and what ends up in the jar depends on the cane, the soil and the mill: one label's iron figure is five times another's. If you are buying it for a mineral, read the label on the jar in your hand.

The sugar, in context

Nine to fifteen grams of sugar is two to three and a half level teaspoons of table sugar (a level teaspoon of granulated sugar weighs 4.2 g) — about what is in a level tablespoon of white sugar, and a little less than the 17 g in a tablespoon of honey. Spoon for spoon, blackstrap is roughly as sugary as the sugar it is meant to replace. It is sugar with a mineral bonus attached, not a mineral supplement with a little sweetness.

Polyphenols and antioxidant scores

Because the cane's plant compounds end up in the molasses rather than in the sugar crystals, blackstrap scores high on laboratory antioxidant tests. In a 2009 comparison of sweeteners bought in U.S. stores, dark and blackstrap molasses had the highest antioxidant capacity by the FRAP test (4.6–4.9 mmol per 100 g), against less than 0.01 for refined sugar, corn syrup and agave nectar and 0.2–0.7 for maple syrup, brown sugar and honey (Phillips 2009). The authors estimated that swapping sweeteners like these for the average 130 g a day of refined sugar could add about as much antioxidant capacity as a serving of berries or nuts. But 130 g of blackstrap is about six and a half tablespoons, and a test-tube antioxidant score is not a health outcome. Evidence tier: laboratory (in vitro) measurement only.

How blackstrap compares with whole foods for the minerals people buy it for is covered in the grey-hair and iron sections below. For the minerals themselves, see Magnesium, Manganese, Potassium and Calcium.

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Grey Hair, Copper and the PABA Era

The grey-hair claim has two strands, and both start from something real.

The copper strand

Hair color is melanin, made by pigment cells (melanocytes) in the root of each hair as it grows. The first, rate-limiting step of melanin production is run by tyrosinase, an enzyme that cannot work without copper. Take copper away and pigment production stalls — which is why copper-deficient animals lose the color of their fur, and why babies with the inherited copper-transport disorder Menkes disease have pale hair. Our page Copper Deficiency: Hair and Skin Pigment explains the mechanism in detail.

But copper deficiency is uncommon, and hair is not where it usually shows. A review in The American Journal of Clinical Nutrition described acquired copper deficiency as mainly a problem of infants — most reported cases were malnourished children — though it is also diagnosed in older children and adults. Its most constant signs are anemia, low white-cell counts and bone abnormalities; loss of hair pigment is among the less frequent ones (Olivares & Uauy 1996). In adults it turns up after some weight-loss and bowel operations, with long-term high-dose zinc supplements, or with long-term tube or intravenous feeding, and doctors usually find it through blood counts or nerve problems rather than through hair color.

The closest human evidence linking copper with everyday early greying is a case-control study from Iran. Sixty-six people under 20 with premature greying had slightly lower average blood copper than 66 matched controls (90.7 vs 105.3 µg/dL; P = 0.048), while their blood iron was actually higher and zinc did not differ (Fatemi Naieni 2012). A study of this design cannot show that lower copper caused the grey hair, let alone that more copper would reverse it. Evidence tier: one small case-control association.

The PABA strand

The second strand is the 1940s rat work described above. For a few years PABA and pantothenic acid were billed as “anti-grey-hair” factors. In people, the idea did not hold up: PABA turned out not to be a human vitamin at all (see PABA), and pantothenic acid (vitamin B5) deficiency is rare. A 2020 systematic review of medicines reported to darken grey hair found 27 studies; it lists PABA and calcium pantothenate among them, rates the evidence for vitamin supplements as low quality, and states plainly that no medical treatment is currently available to repigment grey hair (Yale 2020).

Why most hair actually turns grey

Ordinary greying is not a nutrient shortage. Work in mice and in aging human hair follicles showed that grey hair follows the gradual failure of melanocyte stem cells — the reserve of pigment cells in each follicle — to maintain themselves (Nishimura 2005). When the reserve is spent, the follicle keeps making hair, just without pigment. When that happens is largely inherited and age-related.

So what can a spoonful of molasses do?

USDA's analyzed molasses supplies about 0.10 mg of copper per tablespoon, roughly a tenth of the 0.9 mg Daily Value. Blackstrap is more concentrated and probably carries more, but no USDA-analyzed figure exists and labels do not list copper. For comparison, an ounce of raw cashews provides about 0.62 mg. We could find no study that gave people molasses and measured their hair color. If you are genuinely copper-deficient, that is a diagnosis to confirm with a blood test and correct under medical care, and a spoonful of syrup is a weak way to do it; if you are not, extra copper will not re-darken hair whose pigment reserve is spent — and copper supplements taken for grey hair can cause harm of their own (see Copper). Evidence tier for “blackstrap reverses grey hair”: no human trials; the idea rests on animal deficiency studies and a rare human deficiency.

Molasses as a hair rinse or conditioner

Some videos recommend working molasses into conditioner to darken or restore hair. The visible hair shaft is dead keratin; pigment is laid down in the root as the hair grows. A rinse coats the shaft; it does not feed the pigment cells in the follicle, so it cannot restart pigment production. Sugars hold water, which is why sugary ingredients such as honey appear in some hair products, so a molasses rinse may leave hair feeling softer for a while — but no study has tested molasses on hair at all, and hair that feels softer is not hair that has regained its pigment. If you are losing hair rather than color, see Hair Loss.

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Blood Sugar and the Insulin-Resistance Claim

Start with the arithmetic. A tablespoon of blackstrap carries 9 to 15 g of sugar, close to the 15 g of carbohydrate that people with diabetes count as one “carb choice”. Nothing in molasses cancels that sugar out. The claim that blackstrap “stops insulin resistance almost immediately” traces back to a handful of studies that are worth reading closely, because none of them tested what the videos describe.

The filtered molasses concentrate studies

Two studies by scientists at a private Australian company tested a filtered molasses concentrate: an extract made from cane molasses by a proprietary, patented process, not the syrup in your pantry. In the first, adding the concentrate to a range of carbohydrate foods lowered their blood-glucose response by 5–20% in standard glycemic-index testing, and lowered the insulin response too (Wright 2014). In the second, healthy volunteers took a placebo syrup or increasing doses of the concentrate just before an otherwise identical breakfast, on separate days. Their blood-glucose curves were similar after all five breakfasts; their insulin curves were lower, in step with the dose, and low doses had a larger effect in the people whose measurements suggested more insulin resistance (Ellis 2016). Evidence tier: single-meal studies in healthy people, run mainly by company scientists.

A university-run trial

A university team in Australia then tested a related product, a polyphenol-rich sugarcane extract, in a randomized, placebo-controlled, single-blinded crossover trial. Twelve healthy adults ate a bread meal containing 50 g of carbohydrate with a low or a high dose of the extract, or a sugar-matched control. Neither dose changed the blood-glucose or insulin response. The low dose delayed the insulin peak by 30 minutes; the high dose lowered a calculated insulin-sensitivity score (the Matsuda index) by 9.8%; and the authors summed up the extract's effect as minor (Hewawansa 2026). Evidence tier: small randomized crossover trial, null for its main outcomes.

The rat study

In a Canadian study, rats made obese on a high-fat, high-sugar diet were given a daily dose of 1 g of carbohydrate as refined sugar or as one of six natural sweeteners, molasses among them, for eight weeks. Compared with sucrose, most of the natural sweeteners, molasses included, led to lower fasting insulin and a lower HOMA-IR score, a calculated index of insulin resistance. But glucose tolerance was the same, and fat built up in the liver just as much (Valle 2020). That is a comparison between sugars in animals, not evidence that adding molasses to a diet reverses anything. Evidence tier: animal study.

What this does and does not show

Insulin resistance is a slow, chronic state, measured with fasting tests such as fasting insulin and HOMA-IR (see Fasting Insulin and HOMA-IR). A smaller insulin spike after one meal, in healthy volunteers, from an extract, is not the same thing as reversing it. No study has given blackstrap molasses itself to people with insulin resistance, prediabetes or diabetes and followed them over weeks. What does lower insulin resistance — losing excess weight, regular movement, fewer refined carbohydrates and sugars — is covered on our Insulin Resistance page. If you like the taste of blackstrap, use it instead of other sugar, not on top of it.

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Iron and Iron-Deficiency Anemia

Iron is the other reason people keep a jar of blackstrap: a daily spoonful has been a home remedy for low iron for generations. The labels support part of the idea. Four of the nine blackstrap labels in FoodData Central list 3.6 mg of iron per tablespoon, which is 20% of the Daily Value; the rest list 0.7 to 2.9 mg, and USDA's analyzed generic molasses has 0.94 mg. Some jars are a genuinely useful iron source for a sweetener; others are not.

How much of that iron the body absorbs has never been measured for blackstrap. It is non-heme (plant-type) iron, which is absorbed less efficiently than the heme iron in meat; vitamin C eaten at the same meal improves its absorption, and the polyphenols in tea and coffee reduce it (see Vitamin C and Iron Absorption). Molasses carries polyphenols of its own, so its iron may be less available than the label number suggests — a reasonable inference, not a measured result.

No trial has tested blackstrap molasses as a treatment for iron-deficiency anemia. A 2017 review argued that cane molasses, which its authors note also contains substances thought to aid iron absorption such as fructose and copper, deserves development as a supplement for iron-deficiency anemia, and called for the safety and efficacy research that has not yet been done (Jain & Venkatasubramanian 2017). The closest human data come from a different syrup. In a 1997 Turkish study of 56 children aged 6 to 36 months, grape molasses and ferrous sulfate (a standard iron medicine) raised blood iron about equally in children who were not anemic; in anemic children, the rise after grape molasses (27 µg/dL) was less than half the rise after ferrous sulfate (61 µg/dL) (Aslan 1997). Food iron counts, but it is not a treatment.

The practical reading:

Evidence tier: nutrient content from labels; no human trials of blackstrap for anemia; one study of grape molasses in young children.

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Constipation: One Trial in Children

The best-designed human study of blackstrap molasses itself is not about hair, blood sugar or iron — it is about constipation. Persian traditional medicine used sugar-cane preparations for constipation in children, and a team in Shiraz, Iran, put blackstrap to the test (Dehghani 2019).

What it does not show: whether it works in adults, how it compares with a true placebo, or what it does over months. One trial finding no difference between two treatments is encouraging, but it does not prove they are equal. The mechanism was not studied; a concentrated syrup of sugars and minerals may draw water into the bowel the way osmotic laxatives do, but that is an inference. For children, laxative choices belong with the child's clinician. For adults, the food-first approaches — fiber, fluids, movement, prunes — are covered in Natural Constipation Relief and Constipation.

Evidence tier: one randomized controlled trial in children, compared with an active laxative, lasting one month.

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How People Use It

A tablespoon (15 mL, about 20 g) is the usual “daily spoonful”, and a sensible ceiling for what is still a sugar. Ways to use it:

The whole food comes before any extract. The filtered concentrates and sugarcane extracts in the blood-sugar studies above are processed ingredients, not blackstrap, and their results do not transfer to the jar — in either direction.

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Myths and Overclaims

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Safety and Who Should Be Careful

For most people a tablespoon of blackstrap a day is an ordinary food. The cautions come from its sugar, its potassium, the way it is made, and its stickiness.

Diabetes and prediabetes: it is still sugar

Count each tablespoon as 9–15 g of sugar, about one “carb choice”. There is no evidence that blackstrap lowers blood sugar or improves insulin resistance in people with diabetes (see above), and taking it daily “for blood sugar” adds sugar rather than subtracting it. If you use it, use it in place of another sweetener and check your own glucose response. See Type 2 Diabetes.

Acrylamide

Blackstrap is made by repeatedly boiling sugary cane juice, and heating sugars with the amino acids in plant juice produces acrylamide, the same compound that forms in fried potatoes and toast. In the U.S. Food and Drug Administration's acrylamide survey data, six blackstrap samples from three products measured 290 to 2,160 micrograms per kilogram — potato-chip territory, since potato chips in the same data set had a median of 415. A tablespoon at those levels carries roughly 6 to 43 micrograms. In a Canadian Food Inspection Agency survey of 2,284 foods (2011–2013), syrup and molasses was the category with the highest average acrylamide level, 1,289 parts per billion; Health Canada concluded that the levels found would not be expected to pose a safety concern. The International Agency for Research on Cancer classifies acrylamide as probably carcinogenic to humans, largely on animal evidence. The sensible reading: occasional use is no cause for worry, but a daily-spoonful habit makes blackstrap a steady acrylamide source — one more reason to keep the amount modest.

Kidney disease and potassium

Blackstrap labels list 210 to 600 mg of potassium per tablespoon. For most people, whose diets run short of potassium, that is welcome. It matters if your kidneys cannot clear potassium well — advanced chronic kidney disease or dialysis — or if you take medicines that raise blood potassium, such as ACE inhibitors, angiotensin-receptor blockers or potassium-sparing diuretics. Kidney specialists have moved away from blanket bans on potassium-rich plant foods: a 2020 KDIGO conference noted growing evidence in favor of plant-rich eating patterns in kidney disease, and little evidence that changing the diet alone brings an abnormal potassium level back to normal (Clase 2020). A concentrated syrup taken daily by the spoonful is still exactly the kind of potassium source to clear with your kidney team if your potassium has ever run high. See Kidney Disease and Hyperkalemia.

Teeth

Molasses is thick and clings to teeth. A systematic review carried out to inform World Health Organization guidelines found that 42 of 50 studies in children and all 5 in adults reported at least one link between sugar intake and tooth decay, with moderate-quality evidence that decay is lower when free sugars stay under 10% of daily energy (Moynihan & Kelly 2014). Molasses, like honey and other syrups, counts as a free sugar. Have it with meals rather than as a sipped tonic, and rinse with water afterwards. See Tooth Decay.

Other cautions

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Key Research Papers

  1. Phillips KM, Carlsen MH, Blomhoff R (2009). Total antioxidant content of alternatives to refined sugar. Journal of the American Dietetic Association. — PubMed PMID: 19103324
  2. Olivares M, Uauy R (1996). Copper as an essential nutrient. The American Journal of Clinical Nutrition. — PubMed PMID: 8615366
  3. Fatemi Naieni F, Ebrahimi B, Vakilian HR, Shahmoradi Z (2012). Serum iron, zinc, and copper concentration in premature graying of hair. Biological Trace Element Research. — PubMed PMID: 21979243
  4. Yale K, Juhasz M, Atanaskova Mesinkovska N (2020). Medication-Induced Repigmentation of Gray Hair: A Systematic Review. Skin Appendage Disorders. — PubMed PMID: 32021854
  5. Nishimura EK, Granter SR, Fisher DE (2005). Mechanisms of hair graying: incomplete melanocyte stem cell maintenance in the niche. Science. — PubMed PMID: 15618488
  6. Wright AG, Ellis TP, Ilag LL (2014). Filtered molasses concentrate from sugar cane: natural functional ingredient effective in lowering the glycaemic index and insulin response of high carbohydrate foods. Plant Foods for Human Nutrition. — PubMed PMID: 25373842
  7. Ellis TP, Wright AG, Clifton PM, Ilag LL (2016). Postprandial insulin and glucose levels are reduced in healthy subjects when a standardised breakfast meal is supplemented with a filtered sugarcane molasses concentrate. European Journal of Nutrition. — PubMed PMID: 26410392
  8. Hewawansa UHAJ, Barber E, Houghton MJ, et al. (2026). Impact of Acute (Poly)Phenol-Rich Sugarcane Extract Consumption on Postprandial Glycemic Response in Healthy Adults: A Randomized Crossover Study. Foods. — PubMed PMID: 41750823
  9. Valle M, St-Pierre P, Pilon G, Marette A (2020). Differential Effects of Chronic Ingestion of Refined Sugars versus Natural Sweeteners on Insulin Resistance and Hepatic Steatosis in a Rat Model of Diet-Induced Obesity. Nutrients. — PubMed PMID: 32751772
  10. Jain R, Venkatasubramanian P (2017). Sugarcane Molasses - A Potential Dietary Supplement in the Management of Iron Deficiency Anemia. Journal of Dietary Supplements. — PubMed PMID: 28125303
  11. Aslan Y, Erduran E, Mocan H, et al. (1997). Absorption of iron from grape-molasses and ferrous sulfate: a comparative study in normal subjects and subjects with iron deficiency anemia. The Turkish Journal of Pediatrics. — PubMed PMID: 9433148
  12. Dehghani SM, Bahroloolomifard MS, Yousefi G, Pasdaran A, Hamedi A (2019). A randomized controlled double blinded trial to evaluate efficacy of oral administration of black strap molasses (sugarcane extract) in comparison with polyethylene glycol on pediatric functional constipation. Journal of Ethnopharmacology. — PubMed PMID: 30946967
  13. Clase CM, Carrero JJ, Ellison DH, et al. (2020). Potassium homeostasis and management of dyskalemia in kidney diseases: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference. Kidney International. — PubMed PMID: 31706619
  14. Moynihan PJ, Kelly SA (2014). Effect on caries of restricting sugars intake: systematic review to inform WHO guidelines. Journal of Dental Research. — PubMed PMID: 24323509

PubMed Topic Searches

  1. PubMed: Blackstrap molasses
  2. PubMed: Sugarcane molasses extracts, blood glucose & insulin
  3. PubMed: Copper deficiency & hair pigment

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Connections

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