Health or Hoax? Garlic (Allium sativum)

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By Ari Snaevarsson, Features Editor

What is it?

In this week’s edition of “Health or Hoax?” I will be discussing garlic, otherwise known as Allium sativum, a vegetable well known for its use in cooking and in repelling vampires. What is not so widely appreciated, although a walk through your grocery store’s “nutrition and supplements” aisle might jog your memory, is its’ supplement form’s touted benefits, which include cardio-protection, cancer prevention, and fat loss. These are the claims I will be predominantly examining.

How does it work?

Garlic holds a high amount of sulfur-containing compounds, the principal one (with regards to its health benefits) being alliin. When broken down, via chewing and digestion, it breaks down into allicin, which is now capable of converting into a wide array of sulfur-containing compounds, both water-soluble and fat-soluble.

These compounds give off the gas hydrogen sulfide, recognizable by garlic’s infamous stench. It is this gas that is chiefly responsible for most of supplemental garlic’s benefits. So, what does the evidence actually suggest?

Cardioprotection

When it comes to its cardioprotective benefits, the literature seems to point largely to a significant reduction in low-density lipoproteins (LDL-c, “bad cholesterol”) and total cholesterol, a significant increase in high-density lipoproteins (HDL-c, “good cholesterol”), and minor decreases in blood triglycerides1. Blood pressure, especially in hypertensive individuals, also takes a noteworthy hit when garlic is supplemented into one’s diet2.

Cancer prevention

Its anti-carcinogenic benefits are vastly harder to interpret. Because so little is definitively known about the mechanisms behind cancer, combined with my limited scope of knowledge in even the most basic of its components, I admittedly feel uncomfortable dishing out any sort of wisdom on this topic. I do think anti-cancer properties ascribed to supplements and medicines deserve heavy skepticism, for the former reason.

From the studies I did stumble upon on the matter, and the scarce oncological jargon I actually understood, its anti-cancer claims definitely appear to be blown out of proportion and a lot more research ought to be conducted before such claims can be acknowledged3.

Fat loss

Fat loss is a much easier, although still murky, phenomenon to decode. The first of two major studies I will be examining put rats on an obesity-inducing high-fat diet for eight weeks, followed by an identical diet, this time supplemented with 2% or 5% garlic, and saw a significant reduction in weight in the groups given garlic4.

More interestingly, the study noted a marked decrease in expression of “pro-adipose” genes and an increased expression of uncoupling proteins (which allow for more heat release with cellular respiration). It also made note of increased levels of AMP-activated protein kinase (otherwise known as AMPK, involved in regulation of cellular metabolism and empirically shown to prevent obesity in susceptible rats).

Another study looked at rats with fructose-induced hyperinsulinemia, hyperlipidemia, and hypertension, concluding allicim helped reduce weight versus the control group5. While these two studies are certainly promising, limited human studies, not to mention those looking at healthy subjects, exist.

The conclusion?

Garlic’s cardioprotective benefits certainly appear to be the most pronounced, and the cited lit review1 concludes it may have significant implications when combined with lipid-lowering drugs, by enhancing the body’s response to them. While I do not feel comfortable as any sort of authoritative source of information regarding cancer, its claims deserved some level of observation in this article, and my tentative response to the studies I read would be that a lot more research is warranted before such claims can be affirmed.

Mechanisms seem to be in place for anti-inflammation-mediated fat loss, but I cannot say it indefinitely has these effects or should even be used as a fat loss supplement in otherwise healthy individuals. A lack of studies involving human, let alone healthy human, subjects is telling, as well.

Understand, too, that if fat loss claims found in any supplement weaker than an amphetamine or performance-enhancing drug prove to hold weight, it is at an all but unnoticeable level. The only proven ways to lose significant weight are caloric restriction and exercise, and I will continue to emphasize this point in subsequent articles, because it is a gigantic issue in an equally gigantic population (you can laugh at that).

I hope I did not drag on too much and that you were able to take away some new information on this supplement!

 

Citations

  1. Qidwai, Waris, and Tabinda Ashfaq. “Role of Garlic Usage in Cardiovascular Disease Prevention: An Evidence-Based Approach.” Evidence-Based Complementary and Alternative Medicine : eCAM 2013 (2013). doi:10.1155/2013/125649.
  2. Ried, Karin, Oliver R. Frank, Nigel P. Stocks, Peter Fakler, and Thomas Sullivan. “Effect of Garlic on Blood Pressure: A Systematic Review and Meta-Analysis.” BMC Cardiovascular Disorders 8 (2008): 13. doi:10.1186/1471-2261-8-13.
  3. Kim, Ji Yeon, and Oran Kwon. “Garlic Intake and Cancer Risk: An Analysis Using the Food and Drug Administration’s Evidence-Based Review System for the Scientific Evaluation of Health Claims.” The American Journal of Clinical Nutrition 89, no. 1 (January 2009): 257–64. doi:10.3945/ajcn.2008.26142.
  4. Lee, Mak-Soon, In-Hwan Kim, Chong-Tai Kim, and Yangha Kim. “Reduction of Body Weight by Dietary Garlic Is Associated with an Increase in Uncoupling Protein mRNA Expression and Activation of AMP-Activated Protein Kinase in Diet-Induced Obese Mice.” The Journal of Nutrition 141, no. 11 (November 2011): 1947–53. doi:10.3945/jn.111.146050.
  5. Elkayam, Amitai, David Mirelman, Edna Peleg, Meir Wilchek, Talia Miron, Aharon Rabinkov, Mor Oron-Herman, and Talma Rosenthal. “The Effects of Allicin on Weight in Fructose-Induced Hyperinsulinemic, Hyperlipidemic, Hypertensive Rats.” American Journal of Hypertension 16, no. 12 (December 2003): 1053–56.

 

 

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