What are they?
Ketone is the term used to refer to a particular chemical bond, and any
molecule that contains that bond. A ketone bond is very reactive, which can
allow the aromatization of a molecule containing it.
Aromatization means that we can sense the molecule as a smell. Raspberry
ketones are a major aromatic compound in red raspberries, and thus they are
responsible for the smell of raspberries. Because of this function,
raspberry ketones have been used in cosmetics and perfumes as a scent since
the 1960's. Naturally extracted raspberry ketones exist at about 1-4mg per
kilogram of red raspberries. It would not be possible to eat enough
raspberries to get a physiologically active dose. Because of this, naturally
extracted raspberry ketones are extremely expensive, and so commercially
available varieties are often synthesized in a lab.
There are no studies yet available on the effects of raspberry ketones in
humans. Dr. Oz's advice is based on two research studies involving mice that
were fed high fat diets and high doses of raspberry ketones (1-2% of food
weight). These mice failed to gain as much weight as other mice on the same
diet. When examined, it was found that the mice fed raspberry ketones had
higher levels of the hormone adpionectin. Another study also found that
raspberry ketones promoted the breakdown of fat inside the fat cells to
increase weight loss of mice. Thus, raspberry ketones have been established
as body-fat-reducing in mice.
Raspberry ketones have also recently been studied for their role in
cosmetics. Initial research in mice has appeared promising in this area as
well. Topical application of raspberry ketones has been found to increase
skin elasticity, and to inhibit melanin production. This means that applying
raspberry ketones to the skin of mice was found to reduce wrinkles and
lighten the skin colour. It was also found to promote hair growth in mice
with hair loss (alopecia). These are interesting initial observations, and
further research is required to see if the effects would carry over to
humans as well.
Limitations of the Research
The initial research on raspberry ketones appears very promising.
Unfortunately, because there are no human studies, it is not possible to say
that the effects in mice will also be seen in humans. Although mice are a
good initial test group to examine a general idea of function and safety,
they are genetically different from us and do not always react the same way
humans do to the same substances. Further research using humans is required
to know the safety and efficacy of raspberry ketones in humans.
How fast does it work?
On the show Dr. Oz explains that results can be seen in a few days, and will
progressively increase over time. There are no research studies to back up
his claim at this time. Dr. Oz also stressed that these are not "magic
pills" and that raspberry ketones have to be combined with a healthy diet
and exercise to produce significant weight loss.
There is no established safe dose for this particular supplement. On Dr.
Oz's show a dose of between 100 and 200mg at breakfast was recommended to
help support weight loss when combined with diet and exercise. Despite the
lack of research, because raspberry ketones are extracted from the fruit,
they are generally considered safe.
The difference is that black tea is fermented to produce the characteristic
flavour and this process destroys most of its medicinal benefits. Green
tea's catechins have been well studied, and EGCG (epigallocatechin gallate)
in particular has become a household name.
Green tea also contains L-theanine, an amino acid that promotes relaxed
brain waves in humans. At the same time, green tea contains some caffeine
and nutrients that help to boost mental-alertness. This helps to explain why
green tea helps to improve presence of mind while still having a calming
Green tea is high in catechins, and increased catechin intake (270-1200mg
per day) over a period of at least 12 weeks has been shown to increase the
metabolic rate, reduce body fat, and improve overall weight loss. It appears
that the caffeine in green tea has a synergistic effect to improve these