Study finds almonds lower bad cholesterol and raise good cholesterol
High LDL (“bad”) cholesterol and low HDL (“good”) cholesterol are risk factors for heart disease. Research has shown that eating nuts can reduce LDL cholesterol and raise HDL cholesterol levels in the blood. But because nuts are high in fat and calories, doctors worry that recommending nuts to their patients with high cholesterol might lead to weight gain—another risk factor for heart disease.
New research published online in Circulation: Journal of the American Heart Association suggests that eating almonds may be a good way for people with abnormal cholesterol levels to lower their LDL cholesterol and raise their HDL cholesterol levels.
About the study
Canadian researchers teamed up with the Almond Board of California to study the effects of almond intake on cholesterol levels in 27 men and postmenopausal women (average age 64) with high cholesterol. Other than having high cholesterol levels, participants were in good overall health. They were asked to maintain their usual level of exercise throughout the study, and those taking medications (including cholesterol-lowering drugs) were told to continue their medications as usual.
All participants were instructed to eat a low-fat therapeutic diet of their choice, such as the National Cholesterol Education Program Step 2 Diet (which some were already eating before the study began). The study consisted of three one-month diet phases. During each phase, participants substituted one of the following snacks for one of their usual snacks each day:
- 73 grams of whole unblanched almonds
- A 147-gram, whole-wheat, low-saturated fat muffin
- A half portion of almonds plus a half portion of the muffin
There was a two-week “washout” period between each diet phase in which participants did not eat any of these snacks. Researchers measured participants’ weights, cholesterol levels, and blood pressure at the start of the study and again at weeks 0, 2, and 4 of each diet phase.
The researchers compared weights, cholesterol levels, and blood pressure levels from the start of the study with those at weeks 2 and 4 of the three diet phases.
Note: This study was funded in part by the Almond Board of California.
Compared to cholesterol levels at the start of the study, the phase with a full portion of almonds reduced LDL cholesterol by 9.4% and raised HDL cholesterol by 4.6%. The half-portion phase reduced LDL cholesterol by 4.4% and raised HDL cholesterol by 3.8%. In contrast, the whole-wheat muffin phase produced no reduction in cholesterol levels, but it did increase triglyceride levels (another risk factor for heart disease).
None of the diets produced a significant change in body weight or blood pressure.
Although these results suggest that eating almonds can improve cholesterol levels, this study has its limitations. One limitation, which can also be considered a strength, is that all three diets were tested in the same people rather than in different groups of people. The drawback to this method is that the “washout” period may be insufficient to bring participants’ back to their true baseline status before starting the next diet. Although participants completed seven-day dietary records and kept a record of the almonds and muffins they ate, this type of record keeping is prone to error. There is no way to know how strictly participants adhered to the low-fat therapeutic diet and whether they ate all of their assigned snacks. In addition, they were not supposed to alter their intake of other nuts, fiber, or vegetable protein—a difficult task, especially for people without a good understanding of the nutritional content of various foods. Finally, this study was conducted in a very small group of people. Studies in large numbers of people provide more compelling evidence.
How does this affect you?
Should you add almonds to your diet? Absolutely…though in small amounts. And consider trying peanuts, walnuts, pecans, macadamia nuts, and pistachios as well. This research suggests that people with high LDL/low HDL cholesterol may benefit from eating almonds. And research suggests that other nuts provide cholesterol-moderating effects as well.
Nuts are high in calories and fat, though, so you’ll do best to eat only a small portion. The 73 grams eaten in this study (full portion) is equal to about 2.5 ounces of nuts (a small handful). And remember to use the nuts as a replacement for some other snack you normally eat. Otherwise you’ll just be adding calories to your diet, which can lead to weight gain.
Jenkins DJA, Kendall CWC, Marchie A, et al. Dose response of almonds on coronary heart disease risk factors: blood lipids, oxidized low-density lipoproteins, lipoprotein(a), homocysteine, and pulmonary nitric oxide. Circulation. 2002;106. Published online ahead of print publication.
Last reviewed Aug 23, 2002 by ]]>Elizabeth S. Smoots, MD]]>
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