Almonds for appetite and blood-sugar control and antioxidant power; walnuts compliment wild salmon's cardiac benefits 10/30/2006
This past week was full of positive medical news about almonds and walnuts. And California's nut farmers can use all the good tidings they can get, given the pollination and pilferage problems plaguing them of late.
Thieves called “nut-nappers” have been stealing trailer loads of almonds, while parasitic mites are busy minimizing the numbers of honeybees available to pollinate California's 550,000 acres of almond trees.
The new studies were sponsored by the California Almond Board and the California Walnut Commission, but were conducted at major universities and fit with prior positive evidence, so it's probably pretty safe to take the findings without the proverbial pinch of salt.
Almonds curb appetites
There's substantial evidence that people who eat nuts frequently are less likely to be overweight or to gain weight. For example, women who eat five or more servings of nuts a week have lower-than-average BMIs (body mass indices) and risk of cardiovascular disease (Hu FB et al 1998).
The author of a recent evidence review (Sabate J 2003) noted these facts:
- Population studies show that as nut intake rises, people's body-mass indices drop.
- When people are free to eat as many nuts as desired, they do not gain weight and show a slight tendency to lower weight.
- People on nut-rich diets excrete more fat.
And last weekend, researchers from Purdue University presented the results of a supportive new study at the Obesity Society Annual Scientific Meeting 2006 (NAASO) in Boston.
Their findings add to the evidence that almonds curb hunger very effectively, and that eating a handful or two a day (up to two ounces) may help control your weight.
The Purdue team researchers divided 20 overweight women into two groups for a 20-week study:
- Group A ate two ounces of almonds a day for 10 weeks, and then ate no almonds for the second 10 weeks.
- Group B ate no almonds for the first 10 weeks and then ate two ounces a day for the last 10 weeks.
The weight and BMIs of the women in both groups did not increase, even though the almonds provided about 300 calories a day and the women did not increase their physical activity or their metabolism during the weeks they were eating almonds.
According to lead researcher, Richard Mattes, Ph.D., R.D., “We concluded that the women found their daily almond snack to be very filling, and so they naturally compensated in their caloric intake at other times of the day.”
Based on the evidence we cited above, showing that people on nut-rich diets excrete more fat, the researchers speculated that some of fat calories in the almonds were not digested and absorbed.
Nutty diet controls blood sugar and cholesterol
Three studies presented at the Experimental Biology 2006 conference by researchers from the University of Toronto and Loma Linda University underscore the role of nuts in a healthy diet.
Study #1: Almonds show blood sugar and antioxidant benefits
The first study demonstrated that eating two ounces of almonds (about two handfuls) significantly reduces the blood sugar-raising effect of white bread and that almonds reduce the impact of damaging free radicals, which promote heart disease and diabetes (Josse AR et al 2006).
Researchers compared the blood sugar effect of a high-glycemic (rapid blood sugar-raising) meal containing mashed potatoes with that of two low-glycemic meals: one containing almonds and one containing parboiled rice.
The meal that included almonds produced the least impact on glucose and insulin levels and on measures of oxidative stress.
This finding led the researchers to conclude that antioxidant-rich almonds might reduce the risk of heart disease and diabetes as part of a low-glycemic diet, through mechanisms beyond their moderating effect on blood sugar levels.
Study #2: Nutty, fishy diet rivals statins' cholesterol-cutting effects
The authors of the second University of Toronto study presented in Boston found that eating a certain combination of heart-healthy foods called the “Portfolio Eating Plan”--which is rich in almonds, fish, oatmeal, and lean meats--can help reduce LDL, or “bad,” cholesterol levels as much as the leading statin drugs (Jenkins DJA et al 2006).
Over the course of one year, the Toronto team followed 55 overweight middle-aged men and women who agreed to eat diets high in certain heart-healthy foods: almonds, plant sterol-enriched margarine, soy foods, and viscous fibers from oatmeal, barley and certain fruits and vegetables. One in three was taking statin drugs and blood-pressure drugs.
After one year on the diet, one in three participants had lowered their cholesterol by 20 to 29 percent: an effect equal to that of statin drugs. Of this group, two thirds had included fish and lean meats in their diet.
Participants who adhered to the eating plan less strictly achieved an average 15 percent LDL cholesterol reduction, and even those who strayed furthest from the diet lowered their cholesterol by an average of 10 percent.
Study #3: Walnuts complement heart-health effects of salmon
A friend just passed us this quote from Oprah Winfrey's Web site, regarding their favorite sources of omega-3s: “...our personal choices are: walnuts every day… and fish commonly.”
And it's a good place to start, since a new report validates the wisdom of enjoying both foods on a regular basis.
A team at California's Loma Linda University conducted a rigorous controlled clinical trial designed to compare the effects of adding salmon and walnuts to the diet (Rajaram S et al 2006).
The researchers enrolled 14 men and 11 women, who were assigned to one of three diets, each delivering the same amount of calories:
- Control diet (typical American diet without fish and walnuts)
- Walnut-rich diet (42.5 grams or 1.5 oz six days a week)
- Salmon-rich diet (113 grams or 4 oz of fish, 2 days a week)
The Walnut-rich diet significantly decreased total and LDL (“bad”) cholesterol levels, compared to the Control and Salmon-rich diets.
The Salmon-rich diet increased blood levels of HDL (“good”) cholesterol and decreased levels of triglycerides, compared with the Control and Walnut-rich diets.
This fits with the findings of earlier studies showing that the omega-3s in plant foods and seafood have different, complimentary effects on blood chemistry.
Compared with long-chain marine omega-3s, the short-chain omega-3s in plant foods like nuts do not offer the same degree of risk reduction with regard to cardiovascular disease. However, frequent enjoyment of nuts probably adds substantially to the health-promoting effects of regular consumption of fish and/or fish oil capsules.
Almonds' antioxidant content rivals veggies and tea
When we launched our new Organic Nuts last week, we told you that almonds are high in antioxidants. No sooner had the ink dried on that news than researchers published a study showing that almonds contain the same kinds of antioxidant compounds in many fruits and vegetables, in similar amounts.
A team from the USDA Human Nutrition Research Center on Aging at Tufts University performed tests showing that a one-ounce serving of almonds contains the same amount of flavonoid-class antioxidants as a one-ounce serving of broccoli or a single cup of brewed black or green tea (Milbury PE et al 2006).
And the polyphenol compounds most abundant in almonds (catechin, epicatechin and kaempferol) provide some of the strongest protection against free radicals available from dietary antioxidants.
As lead author Jeffrey Blumberg, Ph.D. said, “These new findings, coupled with past results, lay the groundwork for future clinical trials that examine a link between whole almond consumption and the reduced risk of heart disease and other chronic conditions.”
- Milbury PE, Chen CY, Dolnikowski GG, Blumberg JB. Determination of flavonoids and phenolics and their distribution in almonds. J Agric Food Chem. 2006 Jul 12;54(14):5027-33.
- Chen CY, Milbury PE, Lapsley K, Blumberg JB. Flavonoids from almond skins are bioavailable and act synergistically with vitamins C and E to enhance hamster and human LDL resistance to oxidation. J Nutr. 2005 Jun;135(6):1366-73.
- Jenkins DJA, Kendall CWC, Faulkner DA, et al. Assessment of the longer-term effects of a dietary portfolio of cholesterol-lowering foods in hypercholesterolemia. Experimental Biology 2006.
- Josse AR, Salvatore S, Augustin L, et al. Almonds, Glycemic Index, Dietary Antioxidants and Risk Factors for Coronary Heart Disease. Experimental Biology 2006.
- Rajaram S, Haddad E, Mejia MA, Nguyen L, Tanzman J. Effect of Fatty Fish vs Walnuts on Serum Lipids in Healthy Adults. Experimental Biology 2006.
- Sabate J. Nut consumption and body weight. Am J Clin Nutr. 2003 Sep;78(3 Suppl):647S-650S. Review.
- Fraser GE, Bennett HW, Jaceldo KB, Sabate J. Effect on body weight of a free 76 Kilojoule (320 calorie) daily supplement of almonds for six months. J Am Coll Nutr. 2002 Jun;21(3):275-83.
- Jaceldo-Siegl K, Sabate J, Rajaram S, Fraser GE. Long-term almond supplementation without advice on food replacement induces favourable nutrient modifications to the habitual diets of free-living individuals. Br J Nutr. 2004 Sep;92(3):533-40.
- Hu FB, Stampfer MJ, Manson JE, Rimm EB, Colditz GA, Rosner BA, Speizer FE, Hennekens CH, Willett WC. Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. BMJ. 1998 Nov 14;317(7169):1341-5.