We have a lot of choices to make about our diet. Add to that – doing the right thing when it comes to treating a chronic illness, fighting a virus, or losing weight, and suddenly, our nutrition choices can seem almost overwhelming.
Well, I’m here to help. Welcome to the Nutrition Facts podcast. I’m your host – Dr. Michael Greger.
It’s time for the Nutrition Facts grab bag – where we look at the science on a wide variety of topics. Today, we start with an unusual finding. Did you know that burning incense has been found to generate about four times the particulate matter as burning cigarettes? Here’s the story.
Frankincense and myrrh date back to thousands of years before the three wise men. The burning of which as incense may have actually had hygienic functions––like maybe repelling mosquitoes, and when put to the test, incense fumes were able to kill off some bacteria and mold in the air, but may also carry health risks.
Although the adverse health effects of secondhand tobacco smoke are well recognized, the impact of burning incense in the home has received less attention, but burning incense has been found to generate like four times the particulate matter as cigarettes; so, incense may be even worse! No wonder home incense use may have significant adverse health effects, particularly on the heart and lungs, including childhood asthma. No wonder, since the incense smoke particle size peaks down in the danger range, so ultrafine they can float down into the deepest parts of the lungs.
It’s not just the little ash particles in the smoke though; there’s carbon monoxide, nitric oxides, sulfur dioxide, carcinogenic polycyclic aromatic hydrocarbons, and volatile organic compounds like benzene and formaldehyde. The World Health Organization suggests limiting indoor formaldehyde to about 80 parts per billion, but even with a window open during the hour or so incense is burning, formaldehyde levels exceed the safety limit. What does this all mean in terms of disease outcomes?
Studies on rats show incense can do all sorts of terrible things, but what about people? A study of thousands of children followed over time found that exposure to household incense burning was associated with impaired lung function, reduced lung function growth, and increased risks of respiratory diseases and symptoms. Daily exposure is associated with impaired lung function in adolescents too, though interestingly, those who had pets at home appeared to have better lung function. Something I noted previously, how having a dog or cat in the house during early life may protect against childhood asthma and allergy.
What about the heart? Long-term exposure to incense burning in the home environment was associated with an increased risk of cardiovascular mortality. Approximately 8 percent of heart disease deaths and 12 percent of stroke deaths could potentially be attributed to incense use, though they were looking at long-term exposure, like incense burning at home on a daily basis for over 20 years.
What about cancer? Temple workers exposed to incense day in and day out were found to have evidence of significantly more DNA damage, including DNA strand breaks. Does this translate into greater cancer risk? One unsolved mystery has been why nonsmoking Asian women have such high lung cancer rates. Might it be incense? Probably not, since the association between incense use and lung cancer remains inconclusive––though incense use does appear to be linked to cancers of the upper respiratory tract, as well as brain tumors among children whose mothers were exposed to incense. Three times the odds, even more than that of secondhand smoke. In fact, even more than the consumption of bologna sandwiches. Processed meat consumption only appears to at most double brain tumor risk among children.
Even without tumors, a study of 15,000 infants found that household incense burning was associated with a delay in brain development milestones, such as when they start to walk. And then, on the other side of the life cycle, incense exposure among older adults was associated with reduced cognitive performance and adverse structural changes in the brain. The researchers conclude that this calls for safer practices, such as avoiding burning incense indoors or using safer incense alternatives.
So-called environmentally friendly types of incense have been put to the test, and…they were found to contain even higher concentrations of several potentially carcinogenic polycyclic aromatic hydrocarbons. Despite being a recognized health hazard, burning incense remains in widespread use. In the very least, we may want to avoid burning incense in the home when susceptible individuals are present, such as the very young, the very old, or people with a family history of allergy or pre-existing cardiovascular or respiratory disease.
One innovative suggestion is electronic incense, like the e-cigarette of the incense world; so, you can get the fragrance without the combustion by-products of smoke. Most of the concern about e-cigarette-related adverse events traditionally has revolved around the nicotine, which wouldn’t be a problem with e-incense, the concern that e-cigarette use would lead to real cigarette use. But now that there have been thousands of cases of lung injury associated with vaping, and we’re still actually not sure what’s causing the issue, it seems to me we should figure that out before we push for the electronic incense equivalent.
One option in the meantime is scented candles, which, under normal conditions of use, do not appear to pose known health risks to the consumer.
Next up, we look at specific foods that have shown in randomized controlled trials to improve symptoms like hot flashes.
There is a great variety of symptoms suffered by women undergoing menopause. There are the so-called vasomotor symptoms––like night sweats and hot flashes, difficulty sleeping or full-on insomnia, vaginal dryness and pain during sex, as well as adverse effects on mood, including full-blown depression. Might exercise help? Exercise can certainly help with physical and psychological quality of life in general, but unfortunately there was no evidence for the effects of exercise on menopause-specific symptoms. You know researchers are getting desperate when they try to see if giving people pig placenta will help. Spoiler alert: it doesn’t.
Well, we know oxidative stress, which is a consequence of excessive free oxygen radicals or impaired antioxidant defense, is linked not only to diseases such as diabetes, obesity, and cardiovascular disease, but also menopausal symptoms like hot flashes. Low free oxygen radical defense is associated with more menopausal symptoms, just like having a diet with more antioxidants is associated with fewer menopausal symptoms. In fact, a high intake of fruits and vegetables may delay the onset of menopause in the first place, thought to be because the presence of antioxidants in fruits and vegetables may counteract the adverse effects of free radicals on the number of functional eggs you still have in your ovaries, whereas a reason high meat consumption has been related to degenerative diseases may not just be the saturated fat and cholesterol, but the pro-oxidation products generated during their production, storage, digestion, and metabolism of meat.
Similarly, since a proinflammatory diet has also been associated with higher menopause-specific somatic symptoms, meaning like hot flashes and sleep issues, that would mean moving toward a more plant-based diet packed with anti-inflammatory components like fiber, and away from proinflammatory foods containing saturated fat and cholesterol. No wonder whole plant foods intake has been associated with fewer menopausal symptoms.
In terms of specific foods, poultry and skim dairy products may be particularly bad, whereas soy milk seemed to help. So, women may derive benefit from lower consumption of poultry and skimmed dairy, and a greater consumption of vegetables and soy milk. You don’t really know, though, until you put it to the test. And indeed, women randomized to drink soy milk reduced their menopausal symptoms by 20 percent within 12 weeks.
No wonder that those eating strictly plant-based diets report less bothersome menopausal symptoms. Among women undergoing menopause, vegans reported less bothersome symptoms, and within the diet groups, more vegetables, and in the meat-eating group, less flesh food was associated with less bothersome symptoms as well. So, eating a plant-based diet may be helpful for women in their menopausal transition who prefer a natural means to manage their symptoms––consistent with all the other studies demonstrating reduced menopausal symptoms in those consuming greater quantities of plant-based foods and less meat.
But again, maybe there are other reasons healthier eaters have fewer symptoms. You can’t prove cause and effect until…you guessed it, an interventional trial to see if changing your diet actually reduces symptoms. And in this study, where women were encouraged to decrease fat and increase fruit, vegetable, and whole grain intake, they were significantly more likely to eliminate their vasomotor symptoms like hot flashes and night sweats compared to the control group; so, it’s certainly not all or nothing.
And within a plant-based diet, those randomized to a meat-free diet with daily flaxseed oil, walnuts, and almonds did better than those randomized to the same diet, but with daily extra-virgin olive oil. After 16 weeks, the vegetarian diet that was rich in omega-3s did better reducing vasomotor symptom frequency. In fact, even just two teaspoons worth of ground flaxseeds a day alone can significantly decrease menopausal symptoms to about the same extent as hormone replacement therapy, but without the side effects.
Finally today, we have more info on that fabulous spice fenugreek – and how it controls blood sugar.
The spice fenugreek is considered to be one of humanity’s oldest medicinal plants. What can it do? In my last video on fenugreek, I explored the evidence showing it can improve sexual function in both men and women, decrease menstrual pain, and boost milk production in lactating mothers.
And what are the side effects? Fifteen randomized controlled trials show, on average, a significant improvement in cholesterol levels. And a dozen other studies show significant improvements in both long- and short-term blood sugar control in diabetics and prediabetics using an average of about a half teaspoon a day over a period of an average of two months. Results clearly indicate that fenugreek is an inexpensive, low-risk dietary supplement that has potential to improve blood sugar control in diabetes.
What exactly is the mechanism by which it lowers blood sugars? There’s a peculiar amino acid in fenugreek that increases insulin release from the pancreas.
The peculiar 4-hydroxyisoleucine has been described as an efficient compound in the regulation of insulin secretion. Due to the fact that it acts as a secretagogue in the presence of elevated blood glucose concentrations, it has been proposed for the potential treatment of insulin resistance, diabetes, and obesity. There’s a class of diabetes drugs that does the same thing: sulfonylureas, sold as glucotrol, glyburide, micronase, glipizide. The problem is that they increase insulin secretion whether you need it or not, and so there’s a risk of severe hypoglycemia, driving your blood sugars too low. The funky fenugreek amino acid, on the other hand, only boosts it when you need it. When your blood sugars are normal, it has no effect. It only seems to stimulate extra insulin release when you need it most, when your blood sugars are high.
What these researchers did, was after consent was obtained from family members, pancreases were obtained from brain-dead organ donors. Put the insulin-secreting cells in a petri dish at a low blood sugar concentration, and they release a little insulin, and at high blood sugar levels, they release more insulin. That makes sense. That’s what they’re supposed to do, since insulin is the hormone your body releases when trying to bring down your blood sugars. Add in some of that fenugreek amino acid, though, and you can boost insulin production. Great! But if that happened even at the low blood sugar concentration too, it would be like the drugs, and you could dip too low; but no, when you don’t need extra insulin, no fenugreek effect.
What about the role of fenugreek in the prevention of type 2 diabetes? A 3-year randomized controlled study of the efficacy of fenugreek on men and women diagnosed with prediabetes. Those randomized to fenugreek were told to take about one and a third teaspoons of fenugreek powder twice a day before meals, and both the fenugreek and the control groups that didn’t get any fenugreek were both given identical diet and lifestyle advice. And, by the end of the study, the cumulative incidence rate of diabetes was reduced significantly in the fenugreek group. Check it out. Those who didn’t get the fenugreek had a four times higher chance of developing diabetes, and you could already see the groups starting to diverge within six months, all from just a few cents worth of a spice, every day.
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