Rosemary

Negative side effects of rosemary

Rosemary is a natural herb that has been used by people since 5000 BC [10].

Rosemary extract had no serious negative side effects when used in doses of up to 6000mg [3]. In this study, 28 elderly participants were given 750mg, 1500mg, 3000mg, and 6000mg once, at sessions separated by one week.

What is rosemary?

Rosemary is an herb that has been used for its potential medicinal benefits by the Greeks, Arabians, and many others for more than 7000 years [10]. It has been used as a memory enhancer for a long time, but which active ingredients are responsible for its effects on memory has not yet been discovered.

Which are the bioactive ingredients in rosemary?

One of the main bioactive constituent chemicals in rosemary is 1,8-cineole [5].

Other ingredients in rosemary of interest include α-pinene, camphor [18], pinene, limonene, camphene, myrcene [21], rosmarinic acid, luteolin-7-O-glucuronide, caffeic acid, and carnosic acid [22].

Many of the active ingredients in rosemary, including 1,8-cineole, are also active ingredients in another cognitive-enhancing herb, Sage [1].

Which active ingredients are the most important for memory improvements has not been studied much, so it is hard for consumers to know what they should look for in a product. In one study, it was found that 1,8-cineole in the plasma of humans correlated with cognitive performance after the participants had smelled rosemary essential oil aroma [14]. But it is unclear if it is 1,8-cineole which is bioactive, or if it is just the most easily measured constituent ingredient. There may be other chemicals that are more involved in the cognitive effects of rosemary essential oil, which increased at the same time as 1,8-cineole but weren't measured.

What different forms of rosemary are there?

There are many different forms of rosemary that may improve cognitive functioning, and more specifically, memory. Here are some of the product forms that have been studied for their potential cognitive effects:

• Rosemary essential oil [20]
• Rosemary water [2]
• Rosemary extract [27]
• Rosemary tea [28]

Rosemary essential oil is the most studied form of rosemary for memory enhancement and has been found effective in several studies, but it is crucial that you get the dose right.

How much and how often should you use rosemary?

The different forms of rosemary should be consumed in different amounts.

For the rosemary extract, 750mg, 1500mg, 3000mg, and 6000mg were used in one study. The 750mg dose yielded the most beneficial effects and the least negative side effects of the different doses [29].

As for the essential oil, it is very hard to measure the dose used through inhalation, so we suggest you start low (one normal inhale through your nose close to the bottle), and then subjectively and objectively measure your cognitive performance. Dependent on the results that you get, you may want to breathe in less or more the next time. Eventually, you'll hopefully find your personal sweet spot where you get memory benefits without negative side effects. Alternatively, you may choose to buy a diffuser pad, which is what has been used in studies on the cognitive effects of rosemary [7]. The doses used in the studies have been defined vaguely (e.g. 4 drops, without a defined distance between diffuser and participant [30]) so starting small and working your way up to a point where you experience benefits without side effects is the only practical way to go about it.

In the studies that have found cognitive benefits from rosemary consumption, it was used once. The long-term effects of daily supplementation are not known. The effects of prolonged use may be beneficially cumulative or deleteriously adapted for by the brain (tolerance build-up cannot be ruled out).

How does rosemary work to improve memory?

• Inhibits the breakdown of acetylcholine via reduction of the activity of the enzymes acetylcholinesterase and butyrylcholinesterase [32]
• Phenolic compounds in rosemary have anti-oxidant and anti-inflammatory effects [33][34]
• Enhances cerebral blood flow, a mechanism by which many nootropics may work to enhance cognitive performance [35]
• If used on the skin, some of its active ingredients increase brain activation in the pre-frontal cortex and basal ganglia [36]
  • Using essential oils on the skin can be dangerous - if you want to use rosemary on the skin, find a product that's developed for dermal application
• Carnosic acid, an ingredient in rosemary, "... activates the Keap1/Nrf2 transcriptional pathway by binding to specific Keap1 cysteine residues, thus protecting neurons from oxidative stress and excitotoxicity." [37]

Is rosemary neuroprotective?

In a cell study, rosemary extracts protected human dopaminergic neurons from dying when they were exposed to reactive oxygen species [38].

The authors of another study concluded that carnosic acid and carnosol, two ingredients in rosemary, may have neuroprotective effects [39]. It has been confirmed that carnosic acid is neuroprotective in cells and animals [40].

What time of day should you take rosemary?

No effects on levels of arousal were found in humans when two of the primary ingredients in rosemary, 1,8-cineole and (–)-linalool, were applied to the skin or inhaled [41]. There has been some evidence that people who inhaled rosemary essential oil aroma felt more alert and were more aroused [31], indicating it is best to avoid it in the evening.

The odor of rosemary essential oil is considered stimulating by some [8].

These findings suggest that rosemary can be taken in the morning, or at most other times during the day. However, rosemary might exert slightly stimulating effects, so do not take it too close to bed-time.

What substances may stack well with rosemary?

Rosemary, lemon balm, and sage combined had a strong positive effect after two weeks of use compared with placebo on delayed word recall for younger people, but not in the elderly (above 63 y/o) [44]. This combination of substances was also safe, with no negative side effects observed.

This memory improvement is promising, but more data is needed to confirm the efficacy of the nootropic "stack".

Before combining any drugs or supplements, talk with your trusted medical professional about the risks involved.

Which rosemary product should you choose?

How much of which ingredient you'll get is very unclear for most rosemary products on the market. It is also not at all certain which active ingredients are most important for memory enhancement, and what the optimal dose of each is. We therewith suggest that you find another nootropic that better suits your goals.

However, if you are looking to spend hours self-experimenting your way to an effective dose of rosemary, this is the product we recommend that you buy.