Eating Seaweed Salad May Boost Immune Function

Eating seaweed salad may boost the efficacy of vaccinations and help treat cold sores, herpes, Epstein-Barr virus, and shingles.

Billions of pounds of seaweed are harvested each year, the consumption of which “has been linked to a lower incidence of chronic diseases,” both physical and mental. For example, women who eat more seaweed during pregnancy appear to be less depressed and experience fewer seasonal allergy symptoms. There’s a problem with these cross-sectional, correlational studies, however, in that they can’t prove cause and effect. Maybe seaweed consumption is just an indicator that people generally are following “traditional Japanese dietary customs,” which have lots of different aspects that could protect against disease. To know for certain whether seaweed can modulate immune function, you have to put it to the test.

As I discuss in my video How to Boost Your Immune System with Wakame Seaweed, typically, researchers start out with in vitro studies, meaning in a test tube or a petri dish, which make for quicker, cheaper, and easier experiments. One study, for example, took eight different types of seaweed and essentially made seaweed teas to drip onto human immune system cells in a petri dish. Studies like these showed that the seaweed wakame, which is the kind you find in seaweed salad, can quadruple the replication potential of T cells, which are an important part of our immune defense against viruses like herpes simplex virus.

No one actually gave seaweed to people with herpes until a study published in 2002. Researchers gave people suffering from various herpes infections about two grams a day of pure powdered wakame, which is equivalent to about a quarter cup of seaweed salad. “All fifteen patients with active Herpetic viral infections”—including herpes virus 1, the cause of oral herpes, which causes cold sores; herpes virus 2, which causes genital herpes; herpes virus 3, which causes shingles and chicken pox; and herpes virus 4, also known as Epstein-Barr virus, which causes mono—“experienced significant lessening or disappearance of symptoms,” as you can see at 2:06 in my video. There was no control group in the study, but with no downsides to eating seaweed, why not give it a try?

Researchers also found that wakame boosted antibody production, so could it be useful to boost the efficacy of vaccines? The elderly are particularly vulnerable to suffering and dying from influenza. While the flu vaccine can help, ironically, the elderly are less likely to benefit from it because immune function tends to decline as we get older. So, researchers took 70 volunteers over the age 60. As you can see at 2:50 in my video, their baseline level of antibodies against a flu virus was about 10 GMT. What you’re looking for in a vaccination is to get a two-and-a-half-fold response, so we’d like to see that antibody level get up to at least 25 GMT to consider it an effective response. The vaccine only boosted levels to 15 to 20 GMT, though. What happened after the subjects were given some wakame extract every day for a month before the vaccination? Their levels jumped up to 30 to 35 GMT. The researchers used an extract in a pill rather than the real thing, though, so they could perform this randomized placebo-controlled study. After all, it’s kind of hard to make a convincing placebo seaweed salad.

“It is hoped that the popular seaweeds eaten daily in Japan, though almost unknown around the world outside of Japanese restaurants, will be consumed…for possible immunopotentiation”—that is, immune-boosting potential—“and for attenuating the burden of infectious diseases in the elderly.”

What else can seaweed salad do (other than taste delicious)? See my video Wakame Seaweed Salad May Lower Blood Pressure.

In general, sea vegetables are good sources of iodine, as I discuss in Iodine Supplements Before, During, and After Pregnancy, and may also be one reason Japanese women have historically had such low rates of breast cancer, which I cover in Which Seaweed Is Most Protective Against Breast Cancer?.


What else can we do to boost our immunity? Check out my videos:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Pill-Free Ways to improve Your Sex Life

“Sex is important to health,” according to the Harvard Health Letter. “Frequent sexual intercourse is associated with reduced heart attack risk.” But, as I discuss in my video Do Men Who Have More Sex Live Longer?, that seems to be the perfect case of reverse causation. They’re implying that more sex leads to healthier arteries, but isn’t the opposite more likely—that is, healthier arteries lead to more sex? Blood flow in the penis is so reflective of blood flow elsewhere that penile Doppler ultrasound can predict cardiovascular disease. However, low frequency of sexual activity may predict cardiovascular disease in men independently of erectile dysfunction. This suggests that sex may be more than “just fun” and may also be therapeutic, or at least so says an editor of the Journal of Sexual Medicine and colleagues in discussing whether or not “frequent sexual activity can be prescribed” to improve general health. In men, they suggest it’s because more sex means more testosterone.

When men have sex, they get a big spike in testosterone levels in their blood, but, interestingly, in contrast, they don’t get a testosterone boost when they masturbate, as you can see at 1:21 in my video. This may be because “testosterone increases with competitive success,” like if you win a sports game. While sex “is not usually regarded as a competitive event…one’s mental state following coitus could nevertheless be something like that of a winner,” as opposed to the mental state after masturbation.

As you can see at 2:00 in my video, the spike in sex hormones in the blood is so great that men’s beards actually grow faster on days they have sex. And, since low testosterone levels are associated with increased risk of mortality, this could help explain the health benefits of having sex.

So, do men who have more sex actually live longer? I searched Pubmed for sexual activity and longevity and found a study supported by the U.S. Department of Agriculture, titled “Sexual activity and longevity of the southern green stink bug”—clearly an example of our taxpayer dollars hard at work. I was less interested in whether or not screwworms live up to their namesake and more interested in a study on sex and death, in which the objective was “to examine the relation between frequency of orgasm and mortality.” The researchers found that men with “high orgasmic frequency” appeared to cut their risk of premature death in half and, apparently, the more, the better: There was an associated 36 percent drop in mortality odds for every additional 100 orgasms a year. “Conclusion: Sexual activity seems to have a protective effect on men’s health”—but, apparently, not if you cheat. “Unfaithfulness in men seems to be associated with a higher risk of major cardiovascular events,” like heart attacks and strokes. “Extramarital sex may be hazardous and stressful because the lover is often younger…[and] a secret sexual encounter” may be more stressful.

In a large autopsy series, the majority of cases of sudden death during sex occurred in men during extramarital intercourse. The absolute risk is low—“only one out of 580 men might be expected to suffer a sudden death attributable to sexual intercourse”—but for those at high risk, research shows that “[s]ex in familiar surroundings, in a comfortable room temperature, and with the usual partner adds less stress to the heart” and may be safer.

Speaking of safe sex, you thought drinking and driving was bad? “While it is generally assumed that sexual behavior happens in parked cars, there is little discussion…in the research literature of sexual activity in moving vehicles.” About one in five college students report engaging in sex while driving, nearly half while going more than 60 miles an hour. Researchers suggest maybe this is something students should be warned about in health class.

When done right, though, love may protect your lover’s life. Given the benefits of sexual activity, “intervention programmes could also be considered, perhaps based on the exciting ‘At least five a day’ campaign aimed at increasing fruit and vegetable consumption—although the numerical imperative may have to be adjusted.”

What are some pill-free ways to improve your sex life? Exercising, quitting smoking, not drinking too much alcohol, not weighing too much, and eating a healthy diet. But what does it mean to “eat a healthy diet”? As I discuss in my video Best Foods to Improve Sexual Function, heart-healthy lifestyle changes are sex-healthy lifestyle changes, which have been demonstrated in studies from around the world, including in women. “Sexual function in women is significantly affected” by coronary artery disease, atherosclerotic narrowing of blood flow through our arteries, including the arteries that supply our pelvis. So, high cholesterol may mean “lower arousal, orgasm, lubrication, and satisfaction,” and the same holds for high blood pressure.

Given this, putting women on a more plant-based diet may help with sexual functioning.   Researchers found that improvements in female sexual function index scores were related to an increased intake of fruits, vegetables, nuts, and beans, and a shift from animal to plant sources of fat. The same for men: a significant improvement in international Index of Erectile Function scores. In fact, the largest study on diet and erectile dysfunction found that each additional daily serving of fruits or vegetables may reduce the risk of ED by 10 percent. But why? It may be due to the anti-inflammatory effects. Two years on a healthier diet resulted in a significant reduction in systemic inflammation, as indicated by reduced levels of C-reactive protein. Fiber itself may play an anti-inflammatory role. Those who eat the most fiber tend to have significantly lower levels of inflammation in their bodies, as you can see at 2:06 in my video. The opposite was found for saturated fat, “associated with an increased likelihood of elevated CRP”, C-reactive protein levels.

We’re used to seeing changes in inflammatory markers over weeks, months, or years, but people don’t realize that the level of inflammation in our bodies can change after only a single meal. For example, there’s a pro-inflammatory signaling molecule in our bodies called interleukin 18, thought to play a role in destabilizing atherosclerotic plaque. As such, the level of interleukin 18 in the blood “ is a strong predictor” of cardiovascular death.

What would happen if you fed people one of three different types of meals: sausage-egg-butter-oil sandwiches, cheeseless pizza with white flour crust, or the same cheeseless pizza but with whole-wheat crust? Within hours of eating the sausage sandwich, interleukin 18 levels shot up about 20 percent, an effect not seen after eating the plant-based pizza. In contrast, those eating the whole food, plant-based pizza made with the whole-wheat crust had about a 20 percent drop in interleukin 18 levels within hours of consumption, reinforcing dietary recommendations to eat a diet high in fiber and starches, and low in saturated fat to prevent chronic diseases.

But the billions in profits are in pills, not plants, which is why the pharmacology of the female orgasm has been studied ever since 1972 when a researcher at Tulane University implanted tubes deep within the brain of a woman so he could inject drugs directly into her brain and was able to induce repetitive orgasms. A man who had electrodes placed into similar parts of his brain was given a device for a few hours that allowed him to press the button himself to stimulate the electrode. He pressed the button up to 1,500 times.


For more on male reproductive health, see:

Also check out my other men’s health videos, such as:

What effect might that inflammation directly following an unhealthy meal have on our artery function? Check out my three-part endotoxins series starting with The Leaky Gut Theory of Why Animal Products Cause Inflammation.

And why exactly is fiber anti-inflammatory? Watch my video Prebiotics: Tending Our Inner Garden.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

How to Treat Endometriosis with Diet

“Endometriosis is a major cause of disability and compromised quality of life in women and teenage girls.” It “is a chronic disease which is under-diagnosed, under-reported, and under-researched…[and for patients, it] can be a nightmare of misinformation, myths, taboos, lack of diagnosis, and problematic hit-and-miss treatments overlaid by a painful, chronic, stubborn disease.”

Pain is what best characterizes the disease: pain, painful intercourse, heavy irregular periods, and infertility. About one in a dozen young women suffer from endometriosis, and it accounts for about half the cases of pelvic pain and infertility. It’s caused by what’s called “retrograde menstruation”—blood, instead of going down, goes up into the abdominal cavity, where tissue of the uterine lining can implant onto other organs. The lesions can be removed surgically, but the recurrence rate within five years is as high as 50 percent.

Endometriosis is an estrogen-dependent disease, so might the anti-estrogenic effects of the phytoestrogens in flaxseeds and soy foods help, as they appear to do in breast cancer? I couldn’t find studies on flax and endometriosis, but soy food consumption may indeed reduce the risk of that disease. What about treating endometriosis with soy? While I couldn’t find any studies on that, there is another food associated with decreased breast cancer risk: seaweed.

Seaweeds have special types of fiber and phytonutrients not found in land plants, so in order to get these unique components, we would need to incorporate sea vegetables into our diet. Seaweeds, may have anti-cancer properties, including anti-estrogen effects. Japanese women have among the lowest rates of breast, endometrial, and ovarian cancers, as well as longer menstrual cycles and lower estrogen levels circulating in their blood, which may help account for their low risk of estrogen-dependent cancers. We assumed this was due to their soy-rich diets, but their high intake of seaweed might also be helping.

When seaweed broth was dripped on human ovary cells that make estrogen, estrogen levels dropped. Why? It either inhibits production or facilitates breakdown of estrogen. It may even block estrogen receptors, lowering the activity of the estrogen that is produced. This is in a petri dish, though. Does it happen in women, too? Yes.

Researchers estimated that an effective estrogen-lowering dose of seaweed for an average American woman might be around five grams a day, but, apparently, no one has tried testing it on cancer patients yet. However, it has been tried on endometriosis, as I discuss in my video How to Treat Endometriosis with Seaweed.

Three women with abnormal menstrual cycles, including two with endometriosis, volunteered to add a tiny amount of dried, powdered bladderwrack, a common seaweed, to their daily diet. This effectively lengthened their cycles and reduced the duration of their periods—and not just by a little. As you can see at 3:14 in my video, subject 1 had a 30-year history of irregular periods, averaging every 16 days. Taking just a quarter-teaspoon of this seaweed powder a day added 10 days onto her cycle, up to 26 days, and adding a daily half-teaspoon increased her cycle to 31 days, nearly doubling its length. Furthermore, as you can see at 3:38 in my video, all three women experienced marked reductions in blood flow and a decreased duration of menstruation. For 30 years, subject 1 had been having her period every 16 days, and it typically lasted 9 days. Can you imagine? Then, by just taking a daily half-teaspoon of seaweed, her period came just once a month and only lasted about four days. Most importantly, in the two women suffering from endometriosis, they reported “substantial alleviation” of their pain. How is that possible? There was a 75 percent drop in estrogen levels after just a quarter-teaspoon of seaweed powder a day and an 85 percent drop after a half-teaspoon. 

Of course, with just a few women and no control group in that study, we need bigger, better studies. But, that study was published more than a decade ago and not a single such study has been published since. Millions of women are suffering with these conditions. Does the research world just not care about women? The more pointed question is: who’s going to fund the work? Less than a teaspoon of seaweed costs less than five cents, so a larger study may never be done. But, without any downsides, I suggest endometriosis sufferers give it a try.


For more on endometriosis, see my video What Diet Best Lowers Phthalate Exposure?, and, to learn about the anti-estrogenic effects of the phytoestrogens in flaxseeds on breast cancer, see Flaxseeds and Breast Cancer Survival: Clinical Evidence.

Interested in more on sea vegetables? See:

I recommend staying away from kelp and hijiki, though. Why? See Too Much Iodine Can Be as Bad as Too Little.

Learn more about other natural remedies for menstrual problems:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations: