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Are Legumes Healthy?

December 15, 2009 Written by JP       [Font too small?]

Nutritionists generally concede that there are healthy ways and unhealthy ways of implementing almost any type of diet. There are obviously different points of view about what an optimal menu plan looks like. But ultimately, it’s understood that everything from a vegan diet (no animal derived food) to a ketogenic diet (very in high fat, very low in carbohydrates) can be made healthier by choosing the best dietary options within each diet’s framework. You’ll be hard pressed to find a vegetarian advocate who suggests eating meals consisting of potato chips and mixed cocktails or a low-carb authority who recommends pork rinds and diet soda for breakfast, lunch and dinner.

There’s an issue that all natural health writers must confront at one time or another: How to report on health topics that you don’t personally endorse. My answer to that question is simply to report the facts as I see them in an appropriate context. I then add my own opinion and include additional suggestions about how I believe the information can be best put to use.

By and large, I don’t go out of my way to include legumes (beans, carob, lentils, peas, etc.) in my diet. The one exception to this unofficial rule are peanuts and peanut butter. I choose to avoid this class of fruit because I don’t digest them very well. Also, they wouldn’t really add much value to my nutrient-dense diet. However, this doesn’t preclude me from sharing studies that document the positive health effects of legumes and offering some practical tips about how to derive the greatest possible benefits from this food source while minimizing some of the potential downside.

Scientists from the Agricultural Research Service at the United States Department of Agriculture have just reported that “dark-roasting” peanuts (with their skins on) increases levels of phenolic antioxidants. This may seem counterintuitive to those who believe that raw food is always healthier. In this case, the browning process, which consisted of roasting the legumes at 362 degrees F for 77 minutes, also resulted in larger concentrations of Vitamin E as compared to lightly roasted and raw peanuts. (1)

Another legume, the humble soybean, is the topic of a new study presented in the December 9th edition of the Journal of the American Medical Association. The published trial is based on a population study on over 5,000 Chinese women with a history of breast cancer. The participants were of varying ages (20 – 75) and were monitored for an average of 3.9 years. Interviews and food frequency questionnaires were employed to measure typical soy intake.

  • Women who consumed the largest amounts of soy protein were found to have a 29% reduced risk of death.
  • The high soy protein women also exhibited a 32% lower likelihood of breast cancer recurrence.
  • The greatest level of protection was attained by consuming about 11 grams of soy protein daily.

It’s also interesting to note that the benefits of soy applied to women with both estrogen receptor-positive and negative forms of breast cancer. The use of conventional medications, such as tamoxifin, didn’t appear to affect the protection afforded by soy. (2)

Fermented and “Predigested” Soy Reduces Intestinal Gas
Source: BMC Microbiology 2008, 8:22 (link)

If you look at the official US Department of Agriculture’s “food pyramid” you’ll notice that they strongly support the greater consumption of dry beans and peas. They believe this will help a great many people by adding “higher intakes of fiber, protein, folate, zinc, iron and magnesium with lower intakes of saturated and total fat”. This is in alignment with the rather antiquated view that low fat diets are ideal for overall health and weight loss/maintenance. I won’t address that debate today. However, I will tackle other important considerations for those who choose to include substantial quantities of legumes in their diets. (3,4,5)

Legumes contain a substance known as phytic acid, an “antinutrient” which can impair the absorption of dietary minerals. This is part of the reason why mineral-rich legumes are rarely recommended to address nutrient deficiencies. There are also certain carbohydrates in soy and other beans (alpha-galacto-oligosaccharides) that aren’t digested well by many. This is what often causes bloating and gas after eating such foods. But the good news is that there are some natural ways to improve both of these pitfalls. Researchers are finding that the selective use of fermentation (with probiotics) and germination (sprouting) can dramatically improve the health benefits of legumes, while also allowing for them to be better tolerated. (6,7,8,9,10,11)

The issue of food allergies and/or sensitivities to legumes is another important consideration. Scientists are addressing this by determining the optimal ways of cooking, growing and processing legumes in order to decrease the likelihood of immune reactivity. A fascinating example appears in a recent experiment conducted at the Rio Hortega University Hospital in Valladolid, Spain. There, a group of researchers discovered that adding vinegar to the cooking process can help minimize the allergenic potential of lentils. It’s possible that the organic acids in vinegar work to breakdown some of the more difficult to digest components found in legumes. (12,13,14,15,16,17,18)

Foods affect us in a very individualized manner. Even the healthiest foods are not appropriate for everybody. Broccoli is truly a “super food”, but not for those who are allergic to it. The same is true of other more commonly allergenic foods such as chicken, cocoa, eggs, nuts, etc. All of these are nutrient dense and wonderfully health promoting for the majority of people. But there’s no arguing with your own body if it reacts in a negative way. I think this is this most important principle with regard to legumes. There is simply too much positive evidence to disregard it offhandedly. Therefore, if you have a good reason to eat legumes, do so, but pay close attention to how they impact your health – blood sugar, digestion, energy, mood, sleep, etc. You may be pleasantly surprised to find that they’ll enrich your diet and your life. On the other hand, it could be that you’re one of those people (like me) who finds it best to continue eating them sparingly.

Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!

Be well!

JP

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11 Comments & Updates to “Are Legumes Healthy?”

  1. Nina K. Says:

    Morning JP :-)

    it seems that there are two categories of us: the nuty ones (you me ) and the legumeeaters ;-) . i like lentils, especilly the black ones with balsamico and fish, but one tablespoon to much and i have horrible digestive problems, so too with other legumes. Thank god that there are enough other healthy foods for me :-)

    Best wishes
    Nina K.

  2. JP Says:

    Good day, Nina! :)

    I’m with you on this one. Perhaps the balsamic vinegar helps to improve the digestion of the black lentils? It couldn’t hurt. Still, moderation is probably the key for people like us.

    Be well!

    JP

  3. Jo Says:

    Not to long ago I was eating a salad for lunch at work and two of my coworkers insisted that I should NOT eat raw green beans. I have grown up eating green beans, but I do remember learning in a Medical Botany course that I took that some legumes contained undesirable compounds, but I cannot remember for the life of me what the specific compounds were. These two particular coworkers were from China, and when I googled the issues of raw green beans something came up about China and a particular country in Europe regarding raw green beans as toxic.

    Anyway, minus my anecdote there, maybe it was phytic acid that we learned about because I remember the compounds were anti-nutritive. But I also though they made legumes hard to digest, which goes more along the line of toxicity, which is what lectins are thought to be responsible for (doi:10.1371). I think I am going to have to email my former professor on the subject so I can get it straight. Great post!

  4. JP Says:

    Thank you, Jo. :)

    If you wouldn’t mind sharing, I’d like to know what your professor has to say about it too.

    BTW, I was happy to see that your blog is now a part of the Healthy Monday program. Congrats!

    Be well!

    JP

  5. sheri Says:

    I feel legumes are the bread of nutrition ,, as I consume them .. my body is so pleasantly ]pleased with the benefactors of nutrition

  6. sheri Says:

    legumes are delicious and pleasantly good for the body

  7. JP Says:

    Update 06/21/15:

    http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9781928&fulltextType=RA&fileId=S0007114515001725

    Br J Nutr. 2015 Jun 16:1-7.

    Non-soya legume-based therapeutic lifestyle change diet reduces inflammatory status in diabetic patients: a randomised cross-over clinical trial.

    The present randomised cross-over clinical trial investigated the effects of two intervention diets (non-soya legume-based therapeutic lifestyle change (TLC) diet v. isoenergetic legume-free TLC diet) on inflammatory biomarkers among type 2 diabetic patients. A group of thirty-one participants (twenty-four women and seven men; weight 74·5 (sd 7·0) kg; age 58·1 (sd 6·0) years) were randomly assigned to one of the two following intervention diets for 8 weeks: legume-free TLC diet or non-soya legume-based TLC diet. The latter diet was the same as the legume-free TLC diet, except that two servings of red meat were replaced with different types of cooked non-soya legumes such as lentils, chickpeas, peas and beans over a period of 3 d per week. The intervention period was followed by a washout period of 4 weeks, after which the groups followed the alternate treatment for 8 weeks. Concentrations of inflammatory markers were measured at baseline and after the intervention periods. Compared with the legume-free TLC diet, the non-soya legume-based TLC diet significantly decreased high-sensitivity C-reactive protein, IL-6 and TNF-α in overweight diabetic patients. The replacement of two servings of red meat by non-soya legumes in the isoenergetic TLC diet for a period of 3 d per week reduced the plasma concentrations of inflammatory markers among overweight diabetic patients, independent of weight change.

    Be well!

    JP

  8. JP Says:

    Update 07/10/15:

    http://pubs.rsc.org/en/content/articlelanding/2015/fo/c5fo00290g#!divAbstract

    Food Funct. 2015 Jul 7.

    A comparison of antioxidative and anti-inflammatory activities of sword beans and soybeans fermented with Bacillus subtilis.

    This study was conducted to determine the antioxidative and anti-inflammatory activities of non-fermented or Bacillus subtilis-fermented soybeans and sword beans (red and white). The total flavonoid content in both sword bean types was higher (1.9-2.5-fold) than that in soybeans. The total phenolic content in fermented red sword beans was 2.5-fold greater than that in non-fermented red sword beans. HPLC profiles revealed that gallic acid, methyl gallate, and ellagic acid were major phenolic components of non-fermented/fermented red sword beans. DPPH radical scavenging activity and ferric-reducing antioxidant power were higher in fermented red sword beans than in other beans. Non-fermented/fermented red sword beans had higher nitrite scavenging activity than butylated hydroxytoluene and non-fermented/fermented soybeans. The hyaluronidase inhibitory activity of non-fermented/fermented red sword beans was higher (1.5-2.6-fold) than that of non-fermented/fermented soybeans. These results suggest that B. subtilis-fermented sword beans are potential natural antioxidant sources and anti-inflammatory agents for the food industry.

    Be well!

    JP

  9. JP Says:

    Updated 09/24/15:

    http://www.ncbi.nlm.nih.gov/pubmed/26395434

    Eur J Clin Nutr. 2015 Sep 23.

    Intake of legumes and the risk of cardiovascular disease: frailty modeling of a prospective cohort study in the Iranian middle-aged and older population.

    BACKGROUND/OBJECTIVES: The purpose of this study was to explore the association of legume intake (beans, chickpeas, lentils and so on), as part of a low-glycemic index diet, with the risk of cardiovascular events in the Iranian middle- and old-aged people.

    SUBJECTS/METHODS: A total of 6504 subjects living in the three counties of Iran participated in the Isfahan Cohort Study. Totally, 6323 were free of cardiovascular disease (CVD) at their baseline examination. Of the 6323 individuals, 5398 participants remained in the study for 7 years of follow-up. They have been contacted every 2 years for possible occurrence of CVD events including fatal and non-fatal myocardial infarction, unstable angina, fatal and non-fatal stroke, and sudden cardiac death. The frequency of legume intake was estimated using a food frequency questionnaire. Cox proportional hazards models with shared gamma frailty terms were used to model time to event outcomes.

    RESULTS: After a median follow-up of 6.8 years, 427 cardiovascular events occurred. The intake of legumes in different tertiles of consuming measure was associated with 34% lower risk of CVD in old-aged people, after controlling for the other probable confounders (hazard ratio and 95% CI: 0.66 (0.45, 0.98), P-value=0.039). However, there was no significant association between the frequency of consuming legumes and CVD events in the middle-aged people.

    CONCLUSIONS: The present study indicated a strong inverse relationship between legume intake and the risk of cardiovascular events in old-aged Iranian people.

    Be well!

    JP

  10. JP Says:

    Updated 04/06/16:

    http://www.ncbi.nlm.nih.gov/pubmed/26396436

    J Food Sci Technol. 2015 Oct;52(10):6821-7.

    Sprouting characteristics and associated changes in nutritional composition of cowpea (Vigna unguiculata).

    Cowpea (Vigna unguiculata), is an important arid legume with a good source of energy, protein, vitamins, minerals and dietary fibre. Sprouting of legumes enhances the bioavailability and digestibility of nutrients and therefore plays an important role in human nutrition. Improved varieties of grain cowpea viz. Pant Lobia-1 (PL-1) and Pant Lobia-2 (PL-2) and Pant Lobia-3 (PL-3) were examined for sprouting characteristics and associated changes in nutritional quality. Soaking time, sprouting time and sprouting temperature combinations for desirable sprout length of ¼ to ½ inch for cowpea seed samples were standardized. All the observations were taken in triplicate except soaking time, where six observations were taken in a completely randomized design of three treatments. Results revealed that optimum soaking time of PL-1 and PL-2 seed was 3 h whereas PL-3 required 9 h. Sprouting period of 24 h at 25 °C was found to be desirable for obtaining good sprouts. Significant improvement in nutritional quality was observed after sprouting at 25 °C for 24 h; protein increased by 9-12 %, vitamin C increased by 4-38 times, phytic acid decreased by 4-16 times, trypsin inhibitor activity decreased by 28-55 % along with an increase of 8-20 % in in-vitro protein digestibility.

    Be well!

    JP

  11. JP Says:

    Updated 07/29/16:

    http://www.tandfonline.com/doi/full/10.1080/1028415X.2016.1204744

    Nutr Neurosci. 2016 Jul 7:1-8.

    Cerebrovascular and cognitive benefits of high-oleic peanut consumption in healthy overweight middle-aged adults.

    OBJECTIVE: Peanuts contain bioactive nutrients beneficial for vascular function. This study investigated whether consumption of unsalted peanuts (with skins) would enhance cerebrovascular perfusion and cognitive performance.

    METHOD: In a randomized crossover trial, 61 volunteers (29 males/32 females, 65 ± 7 years, BMI 31 ± 4 kg/m2) consumed their habitual diet ± high-oleic peanuts (56-84 g/day), each for 12 weeks. Nutrient intakes, vascular and cognitive function were assessed at baseline and at the end of each 12-week phase. Differences between the ends of each phase were compared by general linear repeated measures ANOVA controlling for baseline. Pearson’s correlation analyses determined relationships between differences in cerebrovascular reactivity (CVR) and cognitive function.

    RESULTS: Intakes of bioactive nutrients increased during the peanut phase. CVR was 5% greater in the left middle cerebral artery (MCA) and 7% greater in the right MCA. Small artery elasticity was 10% greater after peanut consumption; large artery elasticity and blood pressure did not differ between phases. Measures of short-term memory, verbal fluency, and processing speed were also higher following the peanut phase; other cognitive measures did not change. Differences in CVR in the left MCA correlated with differences in delayed memory and recognition.

    DISCUSSION: Regular peanut consumption improved cerebrovascular and cognitive function; increased intakes of bioactive nutrients may have mediated these improvements.

    Be well!

    JP

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