Summary of Raspberry Ketone
Primary Information, Benefits, Effects, and Important Facts
Raspberry ketone is the compound responsible for many flavoring and aromatic qualities of cosmetics and processed foods.
It should be noted that all evidence for the effects of raspberry ketone has only been observed in vitro (in a test tube). Though researchers are able to raise the concentrations of ketones in a single cell during studies, these same concentrations cannot be replicated in the human body, particularly through oral supplementation.
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Things To Know & Note
Raspberry ketone is said to be non-stimulatory, but this has not been properly addressed by research
Raspberry ketone has a slightly artificial raspberry aroma and taste
How to Take Raspberry Ketone
Recommended dosage, active amounts, other details
There is no human evidence for the effects of raspberry ketones. Studies on rats have used a dosage range of .545-2.18g/kg, which correlates to a human estimated dose of 80-340mg/kg for humans. This dose is very high compared to other fat burning compounds, so for that reason the standard supplemental dose of raspberry ketones for humans is in the 100-200mg range. There is no solid evidence for the effectiveness of the doses listed below. Rat dosages correlate to the following human doses:
870-3,700mg for a 150lb person
1,100-5,000mg for a 200lb person
1,500-6,200mg for a 250lb person
There is no human evidence for the effectiveness of raspberry ketones. Raspberry ketones cannot be concentrated in the human body the same way they are concentrated during studies done outside the body, on single cells.
Human Effect Matrix
The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects raspberry ketone has on your body, and how strong these effects are.
|Grade||Level of Evidence [show legend]|
|Robust research conducted with repeated double-blind clinical trials|
|Multiple studies where at least two are double-blind and placebo controlled|
|Single double-blind study or multiple cohort studies|
|Uncontrolled or observational studies only|
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
|Minor||- See study|
|Minor||- See study|
Studies Excluded from Consideration
Confounded with the inclusion of other fat burners
Scientific Research on Raspberry Ketone
Click on any below to expand the corresponding section. Click on to collapse it.
Raspberry ketone (also known as 4-(4-hydroxyphenyl) butan-2-one) is a compound extracted from red raspberries that is usually used as a scenting and flavoring agent in foods and cosmetics..
It is found naturally in many foods, most notably raspberries (in which case it is synthesized from coumaroyl-CoA) but also in Rheum officinale. Most raspberry ketone used commercially is synthesized or produced via bacteria, however, due to its high demand in cosmetics and as a flavoring agent. It has been estimated that dietary intake for an average human is around 0.42mg/kg bodyweight, mostly consumed through processed foods which have raspberry ketone added as a flavoring agent.
Raspberry ketone has a vaguely similar structure to Synephrine and Ephedrine, where the butanone-substituted phenyl group of raspberry ketone replaces ethylamine group of synephrine or ephedrine. There is also some structural similarity to capsaicin, with para-substituted phenolic and ketone functional groups in common.
After oral ingestion, raspberry ketone is targeted for sulfation and glucuronidation and is also metabolized by the hepatic P450 enzyme system in animal models.
Raspberry ketone (4-(4-hydroxylphenyl)butan-2-one) can be metabolized via ring conjugation (resulting in 4-(4-hydroxylphenyl)butan-1,2-diol) or via side-chain oxidation (resulting in 4-(4-hydroxylphenyl)butan-2,3-diol). Raspberry ketone and its aforementioned oxidized metabolites are excreted in urine, sometimes conjugated to either sulphate or glucuronide.
There is mixed evidence as to whether raspberry ketone can stimulate lipolysis. One study in an adipocyte cell culture model (3T3-L1 adipocytes) noted that 10µM of the compound tripled glycerol release, an indicator of lipolysis. A later, more comprehensive study in the same 3T3-L1 adipocyte cell line found that 10µM raspberry ketone increased the activation of several genes involved in lipolysis, including adipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL).
In contrast, studies on the effects of raspberry ketone on lipolysis in primary cells are not consistent with those in adipocyte cell lines. Primary cells obtained from animal tissue are often better suited to model in vivo processes than continous cell lines such as 3T3-L1 adipocytes, which can have substantial genetic drift from being kept in continuous culture. A study using primary fat cells from a rodent model failed to show any lipolysis-stimulating effects with raspberry ketone alone. This study did note that concentrations in the range of 1-10mM stimulated lipolysis in the presence of norepinephrine, however, suggesting that raspberry ketone may augment norepinephrine- mediated lipolysis in primary adipocytes. There is no detectable binding of raspberry ketone to β-adrenergic receptors, and more research is needed to examine whether raspberry ketone augments norepinephrine- mediated lipolysis in vivo.
Increased secretion and cellular levels of adiponectin were also noted after 4 days of incubating fat cells with raspberry ketone. It has been noted to be protective against steatohepatitis in a rat model while also attenuating a rise in leptin levels.
Although raspberry ketone is a potent stimulator of lipolysis and lipolytic gene expression in the 3T3-L1 adipocyte cell line, studies in primary adipocytes have failed to show an effect. Raspberry ketone has been shown to augment norepinephrine-induced lipolysis in primary adipocytes, however. More studies are needed to assess whether this occurs in vivo.
Raspberry ketone has also been shown to suppress adipocyte differentiation (i.e. the transformation of precursor cells in to adipocytes) and fat accumulation in 3T3-L1 adipocytes by downregulating adipogenic gene expression including PPARγ and C/EBPα.
Rats fed 0.5-2% raspberry ketone (bringing the total daily intake to 0.545-2.18g/kg) during periods of high fat overfeeding noted dose-dependent anti-obesity actions in preventing body weight gain, although the group fed 2% raspberry ketones still gained more weight than the control group fed a normal diet.
Toxicological studies also noted decreases in body weight associated with raspberry ketones at 1% of the diet.
The one human study to investigate the effects of raspberry ketone found a fat loss of 7.8% relative to the 2.8% in placebo, and weight loss of 2% relative to 0.5% in placebo, without detectable differences in caloric intake. This study was highly confounded, however, as raspberry ketone was co-administered with several other supplements in a "METABO" formulation (raspberry ketone paired with caffeine, capsaicin, garlic, ginger and Citrus aurantium as a source of synephrine), so the benefits cannot be traced back to raspberry ketone per se. This study also noted an elevation of serum leptin (but no influence on resistin nor adiponectin) associated with intervention.
Human evidence for the efficacy of raspberry ketones in promoting fat loss is highly confounded. There is no evidence to support the idea that raspberry ketone in isolation can induce fat loss.
In vitro studies with breast cancer cell lines suggest that raspberry ketone can inhibit the androgen receptor, with an IC50 value of 252uM.
Rasberry ketone can block the androgen receptor, but this occurs at high concentrations that may not be physiologically relevant. Oral ingestion of standard (low) doses is unlikely to affect androgen receptor signaling.
A study conducted in rats noted that 1-2% of the diet as raspberry ketone was able to attenuate increases in liver fat associated with a high fat overfeeding diet, with the 2% group not being significantly different than control (control at 10.7+/-1.6mg/g triglycerides in the liver, high fat control at 35.6+/-6.8mg/g, and 2% raspberry ketone at 17.9+/-1.9mg/g). These doses were later tested in another rat model of steatohepatitis, and decreases in liver triglycerides and cholesterol were noted with normalization of serum HDL-C and LDL-C. Liver enzymes were beneficially influenced, although to a minor degree.
It is thought that this is due to a preservation of PPARα and LDL receptors in the livers of rats fed both raspberry ketone and an obesogenic diet.
Rat studies suggest that raspberry ketone may have beneficial effects on liver fat buildup, but there is no evidence to support this effect in humans. Impractically high doses of raspberry ketone were used to achieve these effects in rats.
Raspberry ketone may have some beneficial influences on liver fat buildup, although this has only been tested in rat models, and may not be true in humans. Also, high, impractical doses of raspberry ketone were used to acheive these effects.
Raspberry ketone, used topically as a 0.01% solution applied once daily for 5 months, has been found to increase IGF-1 production in the dermis (skin) and may lead to increased hair growth. These effects seem to be mediated through vanilloid-receptor 1 (VR1) activation, similar to capsaicin, a compound with a similar structure but a longer tail.
Raspberry ketone has also been linked to increased skin elasticity when administered topically as a solution of 0.01% in human females.
Raspberry leaf tea is a herbal medicine traditionally recommended to pregnant women, and contains various compounds such as 'gallo- and ellagitannins, flavonoids, vitamin C, various alcohols, aldehydes, ketones, organic acids, terpenoids, carbohydrates, and glycosides'. The ketones this list refers to are the raspberry ketones, most notably 4-(4-hydroxyphenyl)butan-2-one
In regards to safety during pregnancy, a recent review suggested that not enough information exists to draw a conclusion due to small sample sizes.
There is not much evidence on the safety threshold for raspberry ketone in humans due to its relatively new status as a supplement.
Fat cells show no cytotoxicity, however, at doses up to five times (100μM) the effective dose noted above. In rats, intake of up to 100mg/kg bodyweight does not cause any short-term alterations in markers of blood health, and the LD50 is established at around 1.3-1.4g/kg bodyweight.
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