- Why Are Walnuts Good For My Heart?
- Walnuts vs. All-American Diet
- ‘2–3 oz of walnuts’ daily may benefit heart and gut health
- Nuts may ‘lower’ cholesterol
- Where did the story come from?
- What kind of research was this?
- What did the research involve?
- What were the basic results?
- How did the researchers interpret the results?
- Links to the headlines
- Links to the science
- How to Eat For High Cholesterol
- Tree Nuts and Healthy Fats
- Fish Sourced Omega-3 Fatty Acids
- Oats and High-Fiber Foods
- Sources of MUFAs
- How Nuts Can Reduce your Levels of Cholesterol
- Artery-clogging saturated fat myth debunked
- Coronary heart disease reduced with regular exercise, eating ‘real’ food
Why Are Walnuts Good For My Heart?
1FDA approved claim: Supportive but not conclusive research shows that eating 1.5 ounces of walnuts per day, as part of a low saturated fat and low cholesterol diet, and not resulting in increased caloric intake, may reduce the risk of coronary heart diseas. U.S. Food and Drug Administration, March 2004. One ounce of walnuts provides 18g of total fat, 2.5g of monounsaturated fat, 13g of polyunsaturated fat, including 2.5g of alpha-linolenic acid, the plant-based omega-3.
2Kris-Etherton P. Walnuts decrease risk of cardiovascular disease: a summary of efficacy and biologic mechanisms. J Nutr. 2014; 10: 39:2S-8S.
3Zhao G, Etherton TD, Martin KR, et al. Dietary alpha-linolenic acid reduces inflammatory and lipid cardiovascular risk factors in hypercholesterolemic men and women. J Nutr 2004; 134: 2991-2997.
4Estruch R, Ros E, Salas-Salvado J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J. Med. 2013; 368: 1279-90.
5According to the study referenced above, among persons at high cardiovascular risk, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.
Walnuts vs. All-American Diet
The study involved 13 adults with high cholesterol who were randomly assigned to eat three different diets for six weeks each — with a two-week break in between each diet.
One diet was the average high-fat, high-cholesterol American diet. The other two diets had similar total fat counts as the American diet. But they were low in saturated fat and cholesterol, which are more abundant in animal products, and high in polyunsaturated fatty acids.
In both of the high-poly diets, volunteers got half of their total fat from walnuts and walnut oil:
- The “regular” high-omega-3 diet contained varying amounts of walnuts and walnut oil — specifically, ¼ cup walnuts and 1 tablespoon walnut oil, according to a news release.
- The “high-dose” omega-3 diet contained walnuts, walnut oil, but flax oil, too (West’s paper does not indicate how much flax oil they got).
At the study’s end, the volunteers fasted for 12 hours — then had an ultrasound test to measure how well their blood vessels responded to changes in blood flow. This artery function has been linked to heart disease risk. Their blood was also tested for high cholesterol.
“Cholesterol levels improved after both of the intervention diets, in which saturated fat had been replaced by plant omega-3 fatty acids,” says West in a news release. “But only the higher-dose alpha-linoleic acid diet improved artery function.”
The high-dose group had a sevenfold improvement in artery function, compared with the all-American diet group, says West. While it’s a small study, her findings indicate that walnuts and other plant-based omega-3 oils offer an important benefit to arteries.
The study was funded by the California Walnut Commission.
‘2–3 oz of walnuts’ daily may benefit heart and gut health
The researchers conducted a randomized, controlled trial involving 42 participants with overweight or obesity aged 30–65.
They wanted to see if — and how — adding walnuts to a person’s diet might influence gut health.
To begin with, the research team asked the participants to follow a standard Western diet for 2 weeks.
Then, at the end of this period, the researchers randomly split the study participants into three groups. One group followed a diet that included whole walnuts, the second group ate a diet that included alpha-linolenic acid but in the same quantity that the walnuts would contain. The third group followed a walnut-free diet in which the researchers replaced alpha-linolenic acid with oleic acid.
The participants followed their assigned diet for 6 weeks and then switched diets until each person had followed all three eating plans.
The researchers collected fecal samples from all participants at the end of each diet regimen period. This allowed them to analyze any changes regarding the bacterial populations present in the gastrointestinal tract.
Prof. Kris-Etherton, Petersen, and their colleagues found that individuals who ate 3 ounces (oz) of walnuts as part of an otherwise healthful diet experienced improvements in heart health. The scientists say that these changes were likely mediated by improvements in gut health, as suggested by changes in gut bacteria.
“The walnut diet enriched a number of gut bacteria that have been associated with health benefits in the past,” explains Petersen.
“One of those is Roseburia, which has been associated with protection of the gut lining,” she adds. “We also saw enrichment in Eubacteria eligens and Butyricicoccus.”
The researchers explain that E. eligens has associations with a variety of different aspects of irregular blood pressure. They add that an increase in the population of this bacterium may thus suggest a lower cardiovascular risk.
They also note that an increase in Lachnospiraceae has links with lower blood pressure, total cholesterol, and “bad” cholesterol measurements.
The study did not find any significant associations between any changes in gut bacteria following the walnut-free diets and risk factors for heart disease.
“Replacing your usual snack — especially if it’s an unhealthful snack — with walnuts is a small change you can make to improve your diet,” notes Petersen.
“Substantial evidence shows that small improvements in diet greatly benefit health. Eating 2 to 3 oz of walnuts a day as part of a healthful diet could be a good way to improve gut health and reduce the risk of heart disease.”
– Kristina Petersen
Nuts may ‘lower’ cholesterol
“Eating nuts may help lower cholesterol levels,” BBC News reported.
This news story is based on a pooled analysis of 25 studies, looking at the effects of experimental nut diets on blood cholesterol and fat levels. A nut-enriched diet was found to be associated with both reduced total cholesterol and LDL (“bad”)-cholesterol. On average, in people who consumed 67g of nuts a day, total cholesterol was reduced by 5.1% and LDL-cholesterol by 7.4%. Nut-enriched diets had a lesser effect on reducing the cholesterol levels of people with higher BMIs.
These diets lasted between three and eight weeks, so it is unclear whether this reduction in cholesterol has any effect on the risk of coronary heart disease in the long term. Although nuts are low in saturated fat, they are nevertheless very high in fat and calories. Plain, unsalted nuts should be eaten in moderation as part of a healthy diet.
Where did the story come from?
The study was carried out by researchers from Loma Linda University in California and the Instituto de Salud Carlos III in Barcelona. Funding came from Loma Linda University and the International Tree Nut Council Nutrition Research and Education Foundation. Some of the researchers have also received funding from the California Walnut Commission, the Almond Board of California, the National Peanut Board and the International Tree Nut Council. The study was published in the peer-reviewed medical journal Archives of Internal Medicine.
The research was generally covered well by the newspapers, which all included the advice that people who want to increase their nut intake should avoid salty nuts.
What kind of research was this?
The researchers say that previous epidemiology studies have shown that frequent nut consumption reduces the risk of coronary heart disease. The aim of this research was to see whether it was possible to estimate the effects of nut consumption on the levels of different types of fat in the blood.
The researchers carried out a systematic review and a pooled analysis, in which they grouped the data from various published trials on the effects of nut consumption on cholesterol levels and blood fat. They also wanted to see whether other factors, such as a person’s age or the type of nut, affected the outcomes.
What did the research involve?
The researchers carried out a systematic search of a medical research database for scientific papers which looked at the effect of nuts on blood fat and cholesterol levels, and had been published between January 1992 and December 2004.
To be included, studies had to be based on humans, and either to have had a control group or to have taken stable baseline fat measurements from participants before they started the experimental diet. The experimental diets had to be supplemented solely by nuts, and to have lasted at least three weeks. The participants’ weight also had to have remained the same during the diet. The researchers excluded studies in which participants had taken fat or cholesterol-lowering medication.
Twenty-five studies of various design were suitable for inclusion in the analysis. In studies that had used a crossover design, in which participants received the experimental diet followed by the control diet or vice-versa, participants contributed two data points, one from when they were a control and one where they were receiving the experimental diet. This resulted in a total 1,284 data points and 583 participants.
The researchers looked at whether age, gender, body mass index (BMI) type of nut and type of diet modified the effect of nut consumption on cholesterol and fat measurements in the blood. They also considered the type of study design and the degree of control that the study’s investigator had over the participants’ overall diet, and whether this impacted the effect of nuts on the blood measurements.
What were the basic results?
Compared with control diets, nut diets were associated with a reduction in total cholesterol and levels of low-density lipoprotein (LDL) (“bad”) cholesterol. Nut consumption did not have an effect on the levels of high-density lipoprotein (HDL) (“good”) cholesterol, but it did increase the ratio of HDL compared to total cholesterol (p < 0.001).
Nut diets did not appear to affect blood triglyceride levels, except in participants who had high blood triglyceride levels before the study began, in whom blood triglyceride levels were reduced following the diet (p<0.05).
Age, gender and the type of nut did not influence the effects of nuts on blood cholesterol. However, BMI did have an effect. Participants with a lower BMI at the beginning of the study had lower cholesterol as an effect of eating nuts. Participants with higher LDL-cholesterol at the start of the study had a greater decrease of total cholesterol at the end of the diet.
Participants with LDL-cholesterol greater than 160 mg/dL at the start of the study were associated with a decrease of 17.5 mg/dL (approximately 11%) at the end. Having LDL-cholesterol at less than 130 mg/dL at the study start was associated with a decrease of 5.0 mg/dl (approximately 4% of 130).
The researchers then made estimates of how differing amounts of nuts would affect blood fat and cholesterol levels. They suggested that if a participant ate 71g of nuts per day as part of a 2,000-kcal diet (20% of dietary energy), this was associated with a 4.5% decrease in total blood cholesterol, and a 6.5% decrease in LDL-C.
How did the researchers interpret the results?
The researchers say that their study suggests that “increasing the consumption of nuts as part of an otherwise prudent diet can be expected to favorably affect blood lipid (fat/ cholesterol) levels (at least in the short term) and have the potential to lower CHD risk”.
They attempt to explain the association by saying that “nuts are rich in plant sterols, natural compounds that might contribute to cholesterol lowering by interfering with cholesterol absorption”. However, they also say that “more research is needed to answer the important question of why nuts are less effective in lowering blood cholesterol concentration among subjects with obesity”.
This study conducted a pooled analysis of 25 studies, which looked at the effect that a nut-supplemented diet had on cholesterol and fat levels in the blood. A nut-enriched diet was found to be associated with a decrease in blood cholesterol. There are a few limitations which affect how these results can be interpreted:
- Although the data pooled results from 25 studies the overall population was relatively small. The small size increases the likelihood that the differences observed were due to chance.
- The 25 studies had different diets to which the nut supplementation was added. The researchers did not give details of the energy, fat and cholesterol content of these background diets, which may have varied, potentially affecting the collective results. In addition, the studies varied on the degree of dietary control that the researchers had over the participants, such as whether they checked compliance to the diets or advised on other foods that should be eaten or avoided during the experimental nut diet.
- The experimental diets were typically between three and eight weeks long, which is a relatively short period of time. It is unclear what effect a nut-enriched diet would have over the longer term.
- It is unclear whether the reductions in cholesterol and LDL-cholesterol would be enough to lower the risk of coronary heart disease. Further analysis is needed to assess how much an individual would need to lower their cholesterol in order to lower their risk of coronary heart disease in the long term.
These preliminary results warrant further investigation into how to optimise our diets to lower blood cholesterol levels. As many nuts are heavily salted or coated with sugar and other vegetable oils, people are advised to choose raw unsalted nuts. They should also be aware that although nuts are low in saturated fat, they are nevertheless very high in fat and calories, and should be eaten in moderation as part of a healthy diet.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
Eating nuts can lower cholesterol, say experts.
BBC News, 10 May 2010
How a handful of nuts a day can keep your heart healthy.
Daily Mail, 10 May 2010
Packet of nuts a day ‘can reduce cholesterol levels’.
The Daily Telegraph, 10 May 2010
Links to the science
Sabaté J, Oda K, Ros E.
Nut Consumption and Blood Lipid Levels.
Arch Intern Med 2010; 170: 821-827
How to Eat For High Cholesterol
If you’ve recently visited your doctor and found out that your cholesterol levels are a little bit high, it is important that you begin to make lifestyle changes. Both blood pressure and cholesterol are highly affected by your diet, so we’ve put together a guide to help you eat your way back to a healthy cholesterol number. Here’s some foods that will set you on the right track to lower cholesterol.
Tree Nuts and Healthy Fats
Tree nuts are key players in aiding many illnesses and conditions, including high cholesterol. This is due to their high levels of mono and polyunsaturated fatty acids which are quite helpful in maintaining healthy blood vessels. In turn, this helps to reduce your cholesterol.
Here are a few types of nuts that are both affordable and healthy. Try to eat about a handful each day, or around 50g.
- Pine Nuts
Fish Sourced Omega-3 Fatty Acids
Fish have been a staple in the human diet for all of human history, and for good reason. With their high levels of Omega-3 fatty acids, they assist in keeping a healthy heart and cardiac system overall.
Omega-3 fatty acids don’t have a direct impact on your cholesterol levels, but they are capable of creating better overall health. Try cooking up some fish for dinner, and here’s a few choices to get started with.
Oats and High-Fiber Foods
Oats and other high-fiber foods are the kings of bringing down LDL cholesterol, otherwise known as the “bad” cholesterol. A bowl of oatmeal in the morning can do wonders for regulating your cholesterol.
The soluble fibers of these foods are effective at absorbing free LDL (low-density lipoprotein) from your bloodstream. The less LDL in your bloodstream, the lower your LDL cholesterol will be.
Some great choices for high-fiber foods are:
- Kidney Beans
- Leafy greens
Normally, it only takes five to 10 grams of a soluble fiber each day to produce a noticeable decrease in your LDL cholesterol. If you eat 1.5 cups of cooked oatmeal with some fruit (like a banana), you’ll already be at your quota! Stick with it, and you’ll notice a substantial improvement over time.
Sources of MUFAs
Another great way to target your LDL cholesterol is through the consumption of MUFAs (monounsaturated fatty acids), which also can improve LDL levels in people who are overweight or obese.
Monounsaturated fats are significantly healthier than saturated fats, and can be found in the following types of foods:
- Olives and olive oil
- Peanuts and peanut oil
- Canola oil
- Nut butters
Whether your cholesterol is high or if you are looking to adjust your diet to keep it down, these are some healthy guidelines to get you started. Look for healthy fats, fish, nuts, and most importantly, have healthy portion sizes! For more information on how to keep a healthy diet,
If you are struggling with high blood pressure, obesity, or high cholesterol, it is important that you have a regular family health care provider to help oversee your health and lifestyle changes. Contact the CHC office location nearest you to schedule an appointment with one of our caring providers.
How Nuts Can Reduce your Levels of Cholesterol
With heart disease being the number one killer in the United States, researchers at Loma Linda University Health advise us to go nuts with our health. Patricia Kelikani
Patricia Kelikani, Health Journalist (Co-host): When it comes to your health, it’s okay to go a little nuts. Especially since heart disease is so prevalent in our country.
Dr. Mark Reeves Surgical Oncologist (Co-Host): In fact, one-third of Americans have high LDL cholesterol—the bad kind of cholesterol. Those with high total cholesterol have twice the risk of heart disease compared to people whose cholesterol levels are under 200.
KELIKANI: With heart disease being the number one killer in the United States, researchers at Loma Linda University Health advise us to go nuts with our health.
DR. REEVES: Back in 1993, Loma Linda University Health made a landmark discovery that reversed the health advice from the American Heart Association. Up until then, the organization advised the public against eating nuts because of the high fat content.
KELIKANI: However, Dr. Joan Sabaté discovered that adding one to two servings of nuts to our daily diets could actually cut our risk of having a heart attack in half. During the initial study, the researchers put subjects on a two-month diet known as the American Heart Association step-one diet to lower cholesterol.
DR. REEVES: Half of those subjects were fed the same diet with 20 percent of the calories coming from walnuts. The following month, the groups switched.
Eat a handful of nuts a day to cut your risk of heart disease in half and reduce your cholesterol.Dr. Mark Reeves
Dr. Joan Sabaté, LLU Professor of Nutrition & Epidemiology: “The walnut diet lowered much more the cholesterol particularly the LDL-cholesterol that is considered the bad cholesterol without changes in the good cholesterol, the HDL cholesterol.”
DR. REEVES: Nuts are rich in unsaturated fat— a healthy type of fat that our bodies need to reduce LDLs, the bad cholesterol in our blood. In addition, walnuts have high levels of omega-3 fatty acids. Omega-3s help lower levels of triglycerides, a type of fat in the bloodstream. But nuts are also loaded with protein.
Percent wise and quantity wise it is even greater than the protein that is in meat or in many other animal products. Besides fat and protein, nuts have many other micronutrients such as minerals, vitamins. Dr. Joan Sabaté, LLU Professor of Nutrition & Epidemiology
KELIKANI: For more than 20 years, Dr. Sabaté has been studying the effect of nuts on our health and summarized that one to two servings of nuts a day lowers cholesterol by 10 percent.
DR. REEVES: So what are today’s health tips? Eat a handful of nuts a day to cut your risk of heart disease in half and reduce your cholesterol.
SABATE: “Every morning that I have a smoothie, I put whatever is the ripe fruit that is available, and then two or three handful of nuts, and that is a perfect smoothie.”
KELIKANI: Other ways to incorporate nuts into your diet include topping salads with nuts instead of croutons, or adding them on pizza and pasta. There’s your tip for the day on how you can live healthier, longer.
Artery-clogging saturated fat myth debunked
Among doctors and the public alike, there is a popular belief that dietary saturated fat clogs up the arteries and results in coronary heart disease. A new editorial published in the British Journal of Sports Medicine says that this notion of saturated fat clogging a pipe is “just plain wrong.”
Share on PinterestAccording to researchers, ‘the conceptual model of dietary saturated fat clogging a pipe is just plain wrong.’
The article is the result of a collaboration between a team of cardiologists, including: Dr. Aseem Malhotra, of Lister Hospital in Stevenage, in the United Kingdom; Prof. Rita Redberg, of the University of California-San Francisco School of Medicine and editor of JAMA Internal Medicine; and Pascal Meier, of University Hospital Geneva in Switzerland and University College London, who is also the editor of BMJ Open Heart.
The team cited reviews that show no association between intake of saturated fat and a greater risk of heart disease, in order to support their argument against the existence of artery-clogging saturated fat.
“It is time to shift the public health message in the prevention and treatment of coronary artery disease away from measuring serum lipids and reducing dietary saturated fat,” say the authors. Instead of focusing on lowering blood fats and cutting out dietary saturated fats, the importance of eating “real food,” partaking in regular physical activity, and minimizing stress, should all be emphasized.
According to Malhotra, Redberg, and Meier, the current approach to managing heart disease echoes the practice of plumbing, but the notion of improving the condition by “unclogging a pipe” has been invalidated by a series of clinical trials. The trials found that when a stent was inserted to widen narrowed arteries, the risk of heart attack or death was not lessened.
“Decades of emphasis on the primacy of lowering plasma cholesterol, as if this was an end in itself and driving a market of ‘proven to lower cholesterol’ and ‘low fat’ foods and medications, has been misguided,” the panel contends. These misconceptions may stem from “selective reporting of data,” they suggest.
Coronary artery heart disease is the most common type of heart disease and the leading cause of death for men and women in the United States. The chronic inflammatory condition responds positively to a Mediterranean-style diet, rich in the anti-inflammatory compounds often found in extra virgin olive oil, vegetables, oily fish, and nuts, the researchers note.
Coronary heart disease reduced with regular exercise, eating ‘real’ food
The best predictor of heart disease risk involves a high total cholesterol (TC) to high-density lipoprotein (HDL) ratio, not low-density lipoprotein. Dietary changes, such as substituting refined carbohydrates with healthful high-fat foods including olive oil and nuts, can significantly reduce the high TC to HDL ratio, the experts explain.
Exercise plays an essential role in preventing heart disease and may increase life expectancy by 3.4 to 4.5 years. Just 30 minutes of moderate activity per day on more than three occasions each week has been shown to make a difference to risk factors for inactive adults. Furthermore, the researchers point out that regular brisk walking may be more effective at preventing coronary disease than running.
Chronic stress is a risk factor for coronary heart disease that “should not be overlooked,” the team underline. Chronic stress puts the body’s inflammatory response on a continuous state of high alert. Research has shown that environmental stress, such as childhood trauma, can decrease life expectancy by up to 20 years. The authors write:
“Combining a complete lifestyle approach of a healthful diet, regular movement, and stress reduction will improve quality of life, reduce cardiovascular, and all-cause mortality.”
The researchers add that spending just 22 minutes per day walking and eating healthful food can prevent coronary artery disease. However, “there is no business model or market to help spread this simple yet powerful intervention,” the authors conclude.
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