Newsletter #289: Garlic & Ginger for Blood Pressure Regulation 🍛
Garlic and ginger are probably best known as staples of curry.
However, both of these aromatic ingredients also boast compelling health benefits, particularly when consumed as standardized supplements.
Their effects on cardiovascular markers might be their biggest selling point, which is why I thought I would take a look at recent meta-analyses that examine their effect on blood pressure — and do a little digging into why (in some cases) they might not be so effective.
Let’s take a look 👀
This Week’s Research Highlights
A number of clinical trials have been conducted over the past couple decades examining the effects of garlic supplements on blood pressure. The impact of these supplements can be very impressive. For example, one such trial found that an aged garlic extract led to an average blood pressure reduction of 10 mmHg systolic and 5 mmHg diastolic after 8-12 weeks. Aged garlic may provide greater benefits than fresh garlic, due to an array of biochemical modifications that occur during the aging process.
To assess the effects of garlic extracts on blood pressure, researchers performed an updated systematic review and meta-analysis, including 12 trials with a total of 553 patients with uncontrolled hypertension. The researchers determined that garlic supplements lowered systolic blood pressure by an average of 8.3±1.9 mmHg and diastolic blood pressure by 5.5±1.9 mmHg. That is a reduction comparable to standard blood pressure medications, and would be estimated to result in a reduction in risk of cardiovascular events (heart attack or stroke) by up to 40%, based on large-scale clinical trial data.
Furthermore, the researchers examine recent evidence related to other cardiovascular benefits associated with garlic. For instance, Kyolic aged garlic extract has been shown to normalize blood thickness without increasing risk of excessive bleeding, which can help prevent cardiovascular complications. Kyolic aged garlic has also been shown to improve arterial stiffness. As people get older, blood vessels stiffen, and the pressure waves of blood travel faster through arteries, which can lead to damage to the blood vessels as well as pathological remodeling of the heart. Aged garlic extract has been shown to reverse arterial aging by as much as 5 years.
However, the researchers note that responses to garlic vary considerably between individuals, with almost a fifth of participants in some trials failing to see any improvement in blood pressure. Fortunately, this might be a solvable problem. Bioactive compounds in garlic appear to lower blood pressure by enhancing the production of hydrogen sulfide (H2S), as well as increasing availability of nitric oxide, both of which are key signaling molecules for blood pressure regulation. But the chemical reactions through which sulfur compounds in garlic get transformed into H2S depend upon certain nutrients. Specifically, vitamin B6, vitamin B12, riboflavin, and folate are key co-factors for the main signaling pathways through which garlic works its magic. The researchers suggest that relatively common nutritional inadequacies, due to a combination of diet and genetic factors, may be driving differences in outcomes. Which means that if you're going to take garlic for BP regulation, you should make sure that you're getting plenty of these methyl donors to maximize the potential benefits.
Ginger has been used in Asian countries for centuries as a traditional remedy for a number of physical complaints, perhaps most notably for nausea. Some recent clinical trials have reported that ginger supplementation leads to improvements in blood pressure, however the clinical findings have been inconsistent.
To summarize the state of the literature on this matter, researchers performed a comprehensive review of randomized clinical trials. Six randomized clinical trials, enrolling a total of 345 participants, were included in their meta-analysis.
Their pooled analysis determined that ginger supplementation could reduce systolic and diastolic blood pressure by −6.36 mmHg and −2.12 mmHg respectively, which is comparable to what we see in response to garlic. However further analysis found that blood pressure reductions were only significant in individuals under the age of 50 and in doses at or above 3 grams per day.
It's important to note that the mechanisms through which ginger lowers blood pressure remain unclear, and I think this might explain past inconsistencies in the clinical trials, as well as dosage and product considerations.
Ginger contains a number of unique phenolic compounds, including gingerol and shogaol, which are thought to drive much of the physiological benefits attributed to ginger. However, these constituents may operate at cross purposes with respect to blood pressure regulation. Gingerol, when isolated, seems to work as a natural calcium channel blocker, lowering blood pressure. But animal studies have shown that shogaols may have the opposite effect, actually elevating blood pressure. Shogaols are naturally formed when ginger is dehydrated and exposed to high heat, and lab testing suggests that supplements vary in the balance of gingerols and shogaols. With better understanding of how these compounds work, hopefully more reliable ginger supplements can be devised, and clinical results will be more consistent.
Random Trivia & Weird News
Sometimes regional stereotypes do contain a kernel of truth.
An analysis of data published in the journal Hepatology found that lower average temperature, as well as fewer sunlight hours, was associated with higher total alcohol intake, as well as incidence of binge drinking.
As you can see from the maps below, this link can be found globally as well as within the United States.
Podcasts We Loved This Week
- Debra Skene: The effects of shift work on health and performance. Via Reason & Wellbeing.
- Kaustubh Adhikari: Your pain tolerance may have been passed down from Neanderthals. Via Science Friday.
Products We Like
Kyolic aged garlic extract powder is manufactured from garlic bulbs which have undergone a 20-month aging process in ethanol.
During this time, volatile sulfur compounds found in raw garlic are converted into S-allyl-L-cysteine (SAC), which is the main vasoactive component.
humanOS Catalog Feature of the Week
(Yeah, I know it is somewhat antithetical to the spirit of Thanksgiving, but perhaps we need some healthy reminders around this time, huh?)
Simple food is exactly what it sounds like – food that is prepared and consumed as close as possible to its natural state, with limited added fats and sugars. These types of food enable you to stay satisfied and stave off hunger, while lowering energy density.
In this course, Stephan breaks down the scientific rationale for the Simple Food Diet, what to eat, vital food preparation tips, and other information crucial to lasting success on this plan. For more information, please refer to our How-to Guide for the Simple Food Diet, and the other materials from the Ideal Weight Program.