Nutrient Universe

Saturday, 31 January 2015

Breast milk and protein deficiency

A common idea in the vegan community is that breast milk contains only 5% protein and babies double in size rather rapidly on this small amount of protein. So we only need 5% protein max right?

Indeed breast milk contains only 5% protein roughly, but 5% of what? The problem with this is people assume babies consume the same amount of calories per kilogram of body weight as fully grown adults. They do not. A well fed baby consumes on average 120 calories per kilogram of body weight per day. An adult consumes roughly 35 calories per kilogram. If a grown adult was consuming as much per kg as a baby they'd be consuming somewhere between 8000 and 9000 calories a day. If 5% of those calories were from protein you'd be getting over 100g of protein. The RDA is only 56g for the average male or 44g for a female. Put another way babies get more protein per kilogram of body weight a day. Roughly 3 times more. So this idea doesn't really help anyone figure out adult protein requirements.

http://www.fao.org/docrep/003/aa040e/aa040e07.htm

Friday, 14 December 2012

Does Soy cause Bladder Cancer?

In the Singapore Chinese Health Study, higher soy intake was associated with higher bladder cancer risk. 329,848 people were questioned on their dietary habits. 61 later got bladder cancer. There were more people, with bladder cancer, in the high soy group than the low soy group [1].

So does this mean soy causes bladder cancer? Lets look at what else the study found. Soy intake was significantly associated with intake of vegetables, fruits, vitamins, A, C and E, fish, protein, fat, carotenoids, and energy. So you could say vegetables, and all the other things listed, are associated with bladder cancer in this study. Does this mean vegetables cause bladder cancer? Of course not. There are many studies showing the health benefits of vegetables. Lets look at what other studies have to say about soy.

Four epidemiological studies show an inverse association between soy intake and risk of breast cancer [1]. Soy intake is also associated with decreased prostate cancer risk [2].

In a study done on mice induced with bladder cancer (by nitrosamines), dietary soy reduced tumors [3]. Soy also inhibited growth of both humans bladder cancer cells outside the body, and implanted murine, or human bladder cancer cells in mice [4].

The bladder cancer/soy study goes on to suggest soy could possibly cause cancer as soy supplements raise IGF-1 levels. High IGF-1 levels have been associated with cancer. Indeed soy can raise IGF-1 levels, but no more so than animal proteins. Soy also raises IGFBP-1. This is probably a good thing [5]. For this reason it's wise to limit soy protein as you probably should with animal protein.

Just like in the study on memory decline and tofu in Indonesia where they found it was an additive that causes the association [6], it's possible some of the soy foods eaten in Singapore have cancer promoting substances added to them. The data in the study supports this possibility as the association was weaker with soy protein and soy isoflavone intake.

As of yet, there is no strong evidence that soy contributes to bladder cancer.

Monday, 10 December 2012

Is Cacao Toxic?

The mild toxin in Cacao is theobromine.

Cocoa powder is ground cacao beans with the fat extracted. Cocoa powder contains roughly 2000mg of theobromine per 100g.[1] Cocoa butter contains very little, if any, theobromine.[2] I can't see any evidence suggesting cooking has any effect on the theobromine content of cocoa. So raw and cooked probably have the same levels.

Theobromine is a big problem in dogs. It's hard to find much information on the toxic dose of theobromine for humans. That should tell you something. However, it is said, by some, to be 3 times that of dogs.[3] The toxic dose for a dog is around 130mg per kilogram of body weight.[4] That makes the toxic dose for humans to be about 27, 300mg (average male)or 390mg per kg of body weight. That means you would have to eat over 1kg of cocoa powder in a day. That's like a whole package of the stuff.[5]

I wouldn't say cacao, or cocoa, was a miracle food, like some claim, but it does seem to have some health benefits. It's quite mineral dense for one. One tablespoon of cocoa powder gives you 7% of your magnesium requirements, 9% of your iron requirements (for males), and 23% of your copper requirements.[6] Vitamin wise it doesn't impress.

Cocoa is also very antioxidant dense, having an ORAC score of 3005 per tablespoon.[7] It may also reduce LDL cholesterol, and has been shown to reduce blood pressure.[8][9]

Cocoa butter can raise LDL, but not as much as other saturated fat sources. This is likely because cocoa is high in the saturated fatty acid stearic acid, and low in myristic and lauric acid.[10]

Saturday, 8 December 2012

Acid Forming Foods & Bone Health

Are grains acidic?

PRAL (potential renal acid load)is a rating of how potentially acid or alkaline a food is, calculated on the major acid and alkaline substances.[1] 100 grams of brown rice has a PRAL of around 2. 100g of whole wheat bread has a PRAL of 1.1. This means they're slightly acidic. You could argue the acidifying effect could be less as the calculation is partly based on phosphorus content. Grains may have a lot of phosphorus, but a lot of it is in the form of phytate which isn't even absorbed.[2]

PRALs of other foods per 100g

Chicken broilers, 17.3
Top sirloin steak, 15
Boiled egg, 8.7
Walnuts, 5.5
Almonds, 3
Kidney beans, -0.8
Orange, -3.6
Potato, -5
Banana, -6
Spinach, -11.8
Medjool dates, -13.6

The acidifying substances in the calculation are phosphorus and protein. There is still some debate as to whether high levels of these actually have significant effects on bone health [3][4][5].

Yes they're acidic. No it's not a problem.

Weight Gain on a High Carbohydrate Diet

There's a claim going around that you can't gain weight (fat)on a high carbohydrate, low fat diet. As far as I can tell, this belief is based on things said by Colin Campbell, Neal Barnard and/or personal experiences.

Whilst observing the diets of Americans and rural Chinese, Colin Campbell noticed Chinese people ate more calories than Americans but were slimmer. He put this partly down to them being more active, but also felt that their low protein, not low fat, diet may have played a part, as rodents, and pigs, fed low, sometimes deficient, protein diets gained less weight than those fed high protein diets. It was even found that high fat diets worked better.

I've only seen one study done on humans showing similar effects. They were given high and low protein diets. Overall, people gained less weight on the low protein diet, but for some people the effects of the two diets weren't significantly different. Some even did better on the high protein diet [1]. Again these weren't low fat diets always.

Some say Thermogenisis mops up any excess carbohydrate calories. A few studies have found that Thermogenisis is higher on high protein diets [2][3]. This makes sense as you'll see.

When you eat your body uses energy to digest the food. This produces heat. The harder a food is to digest, the higher the thermic effect and the more energy you burn. Out of the three macro nutrients, protein has the highest thermic effect. The thermic effect of protein is 10 – 20% of calories. The thermic effect of carbohydrate is 5 – 10%, and the thermic effect of fat 0 – 5% [4].

This means a high carbohydrate diet will have a higher thermic effect than a high fat diet with the same protein level. However, a lot of high fat diets are higher in protein than many low fat diets. This might make the difference, in thermogenisis, less significant.

In a study comparing the thermic effect of different types of carbohydrates, sucrose had the highest thermic effect. 10 healthy males were given 75g, or 300 calories, of each carbohydrate type. Over a six hour period, they lost 33 calories, to thermogenisis, with sucrose [5].

If you think higher fibre sugar sources will lead to higher levels of thermogenisis, you're not right. Lower fibre meals induce thermogenisis more than higher fibre meals [6].

What about fat storage?

As with digesting, energy is needed to store energy as fat. Storing fat as fat doesn't require much energy. However, carbohydrate uses 23% of the energy [7]. With this in mind, you should gain less weight when over consuming on carbohydrate compared to fat. Instead of storing 975 out of 1000 excess calories, you would store 770.

Assuming you didn't exercise more to burn it off, if you consumed an excess of 500 carbohydrate calories a day for 1 month, you would theoretically gain over 1kg of fat.

500 – 50 (energy used digesting) = 450 – 104 (energy used converting to fat) = 346 divided by 9 (calories per gram of fat) = 38.4 (grams of fat) x 28 (4 weeks) = 1076g = 1.076kg

A study done on overfeeding fat and carbohydrate supports this. Fat overfeeding led to 90 – 95% of the excess energy being stored. Carbohydrate overfeeding led to 75 – 85% of the excess energy being stored [8].

Unlimited calories and weight loss

What about Neal Barnard's study where they put people on low fat vegan diets, and were told they could eat as many calories as they wanted. They lost weight and their diabetes improved. Does this mean you can eat unlimited calories and not gain weight, or even lose weight? No. They were allowed to eat as much as they wanted, but they averaged about 1400 calories a day [9].

Friday, 7 December 2012

B12 & Vegan Babies

Perhaps you heard about the French couple that went on trial after the death of their child. The parents were vegan and into alternative therapies. The child was breastfed up until her death at 11 months old. She was found to have Vitamin A and B12 deficiency, and died of a pneumonia-related illness.[1]

I'm not here to hate on these people. What's done is done. They've probably learnt their lesson, and it's none of my business. It could so easily happen again however, and it could so easily be prevented. How can we do this?

I have nothing against babies being brought up as vegans, or breastfed. It's said that babies should be started on solids after six months, but I don't really feel that's the big issue here. The big issue is that the mothers milk was inadequate to support her baby. The mothers milk likely didn't contain enough Vitamin A or B12. This was probably because the mother herself lacked those vitamins. B12 deficiency can be fixed relatively easily with supplementation. If you're not already deficient, oral B12 should be enough to keep you from becoming deficient, but if you're planning to breast feed your newly born baby and you know you're deficient, it's probably best you take B12 injections as they work to fix deficiencies faster.[2][3] Alternatively you could perhaps pump breast milk, put it in a bottle and mix it with some kind of B12 supplement. Discuss with your doctor. You could also choose not to breast feed and give your child a vegan baby formula.[4] One final option could be to get someone else (healthy)to breastfeed your child.

Vitamin A deficiency is rare in adults. If the mother was deficient in Vitamin A, she may not have been taking in enough, but more likely explanations would be lack of fat in the diet, needed to absorb Vitamin A, or thyroid issues which can apparently interfere with the conversion of plant Vitamin A to Retinol.[5][6]

Thyroid issues can be caused by lack of iodine, or too much iodine.[7] It's more likely vegans will suffer from lack of iodine unless they consume the seaweed Kelp, in which case they could be getting too much iodine. Most people get their iodine from iodized salt, fish, or milk. There is iodine in fruits, vegetables, legumes and grains, but the amount of it depends on the soil quality.[8]

Some naturalist people insist we don't need to take B12 supplements, because B12 is in plant foods and the air. They suggest B12 deficiency is an absorption issue, and that a fast can fix this. I've seen no evidence to suggest these things. B12 is found in plant foods, but likely in amounts too small. There isn't much data on it. Your body does have bacteria that produces B12, but it's in the large intestine. The small intestine is the absorption point for B12.[9]

Thursday, 6 December 2012

Is Cooked Food Toxic?

In the raw food movement, there are three main arguments for why you should eat a raw food diet. They are as follows:

We haven't been cooking very long
Cooking creates toxins, and carcinogens
Cooking destroys nutrients

How long have we been cooking?

In his book “The 80/10/10 Diet”, Douglas Graham states we've likely only been cooking regularly for 10, 000 years. He states it takes around 50, 000 to 500, 000 years for evolutionary change to occur.

There's a lot of agreement among anthropologists that human ancestors were cooking their food as long ago as 250,000 to 500,000 years, but Richard Wrangham and a few of his colleagues see evidence that cooks spoiled the broth as long ago as 2 million years. That's about the time when our ancestors became less like apes and more like humans [1].

Italian wall lizards introduced to a tiny island off the coast of Croatia are evolving in ways that would normally take millions of years to play out. In just a few decades the 5-inch-long lizards have developed a completely new gut structure, larger heads, and a harder bite [2]. Exceptions don't make the rule of course, but consider that we could also be an exception and that it is uncertain how long adaptations take if they even need to occur.

If we had only been cooking consistently for 10, 000 years, we would have reason to suspect we may not be adapted to it, but it wouldn't prove anything. We need studies showing the negative effects of cooking.

Does cooking really create toxins, or carcinogens?

Many of the people promoting raw food diets say cooking creates toxins, often without mentioning what toxins, or giving any real proof. The following are all the potential, or proven, toxins I'm aware of that are created, or elevated, by cooking.

Acrylamide

Acrylamide is known to cause cancer in animals. Also, certain doses of acrylamide are toxic to the nervous system of both animals and humans. Acrylamide is formed by frying, baking and grilling. Acrylamide has not yet been found in foods cooked below 120 degrees Celsius.[3] If it were found, levels would be very low. High intakes have been linked to certain cancers [4].

HCAs and PAHs

Exposure to high levels of Heterocyclic amines (HCAs)and Polycyclic aromatic hydrocarbons (PAHs)can cause cancer in animals; however, whether such exposure causes cancer in humans is unclear. Benzanthracene, benzofluoranthene, benzopyrene, dibenzanthracene, and indenopyrene are examples of PAHs. HCAs and PAHs are formed when muscle meat, including beef, pork, fish, and poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame [5].

Nitrosamines

Nitrosamines have been proven carcinogenic in many species. They are probably carcinogenic to humans too [6]. Nitrosamines are made from nitrates. Nitrates are found in some vegetables, but Nitrosamines are not. They are mostly found in meat and dairy [7][8].

Acrolein

Small amounts of acrolein may be found in some foods, such as fried foods, cooking oils, and roasted coffee [9]. The Department of Health and Human Services (DHHS) has not classified acrolein as to its carcinogenicity. The International Agency for Research on Cancer (IARC) has determined that acrolein is not classifiable as to carcinogenicity in humans. The EPA has stated that the potential carcinogenicity of acrolein cannot be determined based on an inadequate database [10].

AGEs

Advanced Glycation End Product levels aren't significantly different in raw and cooked plant foods. Some cooked items have lower levels than some raw items even [11].

If you're avoiding animal products, as well as grilled, baked and fried foods you shouldn't be consuming any potential, or proven, toxins or carcinogens. Although it can be said that those things are likely harmful to health.

Cooking destroys nutrients

Whilst this is true, the important question is, is a diet containing a lot of cooked food deficient in nutrients? Are raw food diets always better than diets containing cooked food? Of course a diet containing mostly cooked could potentially be deficient in nutrients, just the same as with raw diets, but it isn't necessarily deficient.

Lets take Vitamin C. Raw foodists will often talk about how cooking destroys Vitamin C. This is true. Vitamin C is very heat sensitive. It's also very important. The RDA is 90mg. You may benefit from getting more than this, but this isn't important for now. How can we obtain the RDA? 2 raw oranges give you 155% of the RDA, 1 raw red pepper gives you 169%, and 200g of boiled broccoli gives you 144%. This isn't a difficult nutrient to get a lot of.

Many 80/10/10 dieters rely on the banana as a staple. There's a calorie dense cooked food that beats the banana for Vitamin C content. The banana contains about 10mg of Vitamin C [12]. A boiled potato contains about 17mg of Vitamin C [13]. Yes cooking destroys Vitamin C. The potato had 42mg before cooking [14].

What if we need more Vitamin C? Out of all raw food dieters, 80/10/10 dieters probably get the most. The most popular 80/10/10 site on the internet is 30bananasaday.com. The creator of the site pushes high calorie fruits like bananas and dates. According to the records, dates don't contain any Vitamin C. Bananas aren't bad for Vitamin C, but you could get the same amount of Vitamin C as a person eating 30 bananas by eating 5 oranges a day. So eating a raw food diet doesn't necessarily mean you're getting more Vitamin C.

Denatured protein

Some will claim denatured protein is toxic and/or unusable. I see no evidence for it being toxic. Denatured proteins are actually more digestible [15]. A study tested the protein digestibility of raw and cooked egg. The cooked (denatured)egg protein was absorbed 41% more [16]. When you denature a protein it loses it's secondary and tertiary structure [17]. It's primary structure remains in tact. This is the important one. Your stomach acid denatures protein also [18][19].