Bottom line: An ounce a day of nuts does not protect against heart disease, despite what this â€śdoctorâ€ť may assert.
I went to the trouble of analyzing some false claims coming out of Dr. Michael Greger on his website nutritionfacts.org. There are really too many to spend time on, so I thought I would just look at the most recent.
I am a retired biology professor who is interested in healthy plant-based diets and have read and followed all the experts over time. Let me say that I eat nuts in moderation as part of my healthy plant based diet, and believe they are a healthy food. I am not "anti-nut" but want to help set the record straight about the relative importance of nuts in a healthy diet. Nut consumption is in no way crucial for good health, despite being so portrayed by the nut industry and their press releases.
I watched Dr. Greger's recent 2-part video presentation today called, â€śHow do nuts prevent sudden cardiac death?â€ť In it, Dr. Greger points out that low levels of magnesium appear to be a marker for heart disease, and that added nut consumption offers potential protection due to the magnesium content of nuts.
The pitch goes something like this: magnesium is important for heart health, post-mortems of people who died of heart attacks all showed low levels of magnesium. A study of vegetarians shows that vegetarians get a bit more magnesium than non-vegetarians, but still less than recommended. Nuts are an excellent source of magnesium, so vegetarians should be adding nuts to their diets to protect against heart disease.
What is wrong with that argument is simply . . . everything.
It has been long known that magnesium is an essential mineral, involved in nearly every function of the body, including the heart. The National Institutes of Health say magnesium is the fourth most abundant mineral in the body and essential to good health. Only 1% of magnesium is found in blood, but the body works very hard to keep blood levels of magnesium constant. For more on magnesium, see this information page on the NIH website: http://ods.od.nih.gov/factsheets/Magnes ... fessional/
Do people who suffered fatal heart attacks have low levels of magnesium? Apparently they do. Why? Because just about everyone in the US population is suffering from magnesium deficiency, since they eat the Standard American Diet (SAD).
Dr. Greger cites a study of vegetarians, which shows that, while vegetarians have higher blood levels of magnesium than non-vegetarians, it is still too low. Those vegetarians need to clean up their diet to prevent heart attacks, he says, starting with nuts.
So let's start by looking at the study cited on vegetarians in the argument. The study is: A Vegetarian Dietary Pattern as a Nutrient-Dense Approach to Weight Management: An Analysis of the National Health and Nutrition Examination Survey 1999-2004
You can download the full study from http://veg.ca/images/pdf/farmer.pdf
Looking at the study, reviewers compared the diet of 432 lacto-ovo vegetarians to 8,255 nonvegetarians. Both failed to meet the RDA for magnesium.
So what were the vegetarians eating? As you can see when you look at the study itself, they ate a very unhealthy junk food diet.
According to Table 3 in the study, they ate lots of processed grains and little whole grains. (Processed grains contain far less magnesium than whole grains, which are higher.) They ate little fruit, the same amount of vegetables as the nonvegetarians. The vegetarians also ate meat, poultry, fish â€“ seriously! It's all there for anyone to see in Table 3. They ate more eggs, milk and cheese than the nonvegetarians, and they ate more sugar and more oil than the nonvegetarians.
â€¨In other words, the vegetarians in the study ate an incredibly unhealthy diet. Why is this important? Because much of the discussion around nuts in our niche is aimed at people who are already eating much different diets. Most of the discussion around nuts are in places like these discussion forums of Dr. McDougall, Dr. Fuhrman, Dr. Esselstyn, Dr. Barnard and so forth.
So this study of vegetarians who are eating a just slightly better diet than the SAD eaters in no way applies to people eating the kinds of healthy plant-based diets where this issue is being discussed.
â€¨Moreover, if you look at Table 3 of the study, you will see that the vegetarians were eating more nuts than the nonvegetarians â€“ about .89 ounces of nuts a day on average, so almost an ounce serving a day. And yet this did not help them. Dr. Greger and some others advocate an ounce of nuts a day as practically mandatory. And yet the vegetarians, who were consuming almost an ounce per day, were still lacking in magnesium.
â€¨The real problem this study of vegetarians underscores has nothing to do with nuts. The problem is that they were eating only 1.2 ounces of whole grains, which is far below the bare minimum of 3 ounces set by the USDA, and way below the 5-8 ounces which are recommended. They only took in .23 cups of vegetables (non potato) which is way below the recommended 2-3 cups per day. They consumed only .22 cups of beans, which is far below the recommended level.
So the vegetarians in the study do not even meet the minimum USDA standards for a nutrient dense diet.
That is the crux of the issue, not whether these people were eating enough nuts to prevent a heart attack.
If you look at Table 4 of the study, you will see that out of a possible healthy eating score of 100, the vegetarian group scored only 50.5, since they were so low in all fruits, vegetables and whole grains. A typical Fuhrman, McDougall, Barnard or Esselstyn diet would easily score 90 or more.
This study actually shows why Americans (including the lacto-ovo vegetarians in the study) should switch to a healthy plant-based diet, like those of McDougall, Barnard, Fuhrman or Esselstyn. The study does not show why people need to eat nuts. So the issue is not just about magnesium, or any one nutrient, even though Dr. Greger likes to approach diet this wrongheaded way.
But in terms of magnesium, nuts are actually a poor source and score fairly low in regard to nutrient density. To make it appear nuts are good sources of magnesium, Dr. Greger compares foods by weight or volume. But as we well know, using weight or volume to compare foods is an outdated food industry trick and does not give the real picture. The correct comparison is the amount of nutrients per calorie.
The idea of nutrient density and why food should be evaluated by the calorie is that, for example, to get the daily RDA of 400 mg. of magnesium, you can eat 93 calories of Swiss chard, or 857 calories of almonds, including all the added fat. Clearly, the Swiss chard is the better source, not only for magnesium, bur for all other vitamins, minerals and phytochemicals.
Lets look at it another way to really see the point..Per 100 calories of Almonds and Swiss ChardAlmonds/Swiss Chard
Protein gm 3.7/ 9.4
Fiber gm 2.1/ 10.5
Folate mcg 8.7/45
B1 mg 0/.2
B2 mg .2/.4
B3 mg .6/1.8
B5 .mg .1/.8
B6 mg 0/.4
C mg 0/90
E mg 4.6/9.4
K mcg 0/1636
Choline mg 9.1/143.5
Calcium mg 46/290
copper mg .2/.8
iron mg .6/11.3
magnesium mg 47/430
manganese mg .4/1.7
phosphorus mg 84.2/165
potassium mg 123/2745
selenium mcg .4/4.5
zinc mg .5/1.7
Swiss chard beats almonds in EVERY way.
As long as you are eating a whole foods plant based diet, with all the whole grains, beans, fruits, starchy veggies and veggies, how mandatory are nuts? You can certainly include nuts. But mandatory? Poppycock.
There is an old saying, that â€śbullsh*t baffles brains.â€ť What it means is you can't just rely on someone making generalizations, mentioning some studies and one or two aspects of what a study says, and then automatically accept their conclusions. That's important if you don't want to get sucked into someone else's agenda.
Here are sources of magnesium in various foods, from http://nutritiondata.com
Dietary sources of magnesium per 100 calories, from highest to lowest:
Swiss Chard cooked, 430
Purslane, raw 425
Spinach, cooked, 378
Beet Greens, raw, 318
Beet greens cooked, 257
Scotch Kale, raw, 210
Scotch Kale, cooked, 204
Okra, cooked, 182
Zucchini, raw, 157
Bok Choy, raw, 146
Navy Beans, 143
Parsley, raw, 139
Turnip greens, cooked, 110
Pumpkin Seeds 103
Savoy Cabbage, cooked, 100
Cowpeas, cooked, 82
Amaranth cooked, 64
Buckwheat, cooked, 56
Quinoa Cooked, 54
Cashew Nuts, 53
English Walnuts, 24
Pistachio nuts, 22
Sunflower Seeds, 22