How many working brain cells do researchers have? Part n+1

Once upon a time, I took the mickey out of some eejit researchers in How many working brain cells do researchers have? Guess what? I'm doing it again. A Facebook friend sent me a link to a worrying "new" study Omega-3 Supplements Linked To Prostate Cancer. Oh, dear. Things are looking bad for oily fish & fish oil supplements. Just a moment!

I did some digging on PubMed for the author and found this:- n-3 Fatty acids and prostate cancer risk. The main feature of wild oily fish & fish oil supplements is their high ratio of EPA & DHA (long-chain omega-3 fatty acids) to LA (a shorter-chain omega-6 fatty acid). It would therefore be logical to assess oily fish consumption and/or fish oil supplement intake by measuring the ratio of serum EPA:LA and/or DHA:LA and/or (EPA+DHA):LA.

What did Brasky TM, Crowe FL & Kristal AR actually do? According to the abstract, they measured only serum EPA, DHA & (EPA+DHA). They didn't measure serum LA. Therefore, if the subjects in the EPIC study ate a diet with a high omega-6 (n-6):omega-3 (n-3) ratio (i.e a Standard English Diet), subjects with a high serum n-3 level would have a very high serum n-6 level. As excessive levels of serum n-6 pufas are carcinogenic (see Completing the trine: Which are the safest fats?), it's not surprising that the study produced the results that it did.

There only one thing to do, in cases like this...

Because one palm just isn't enough!

EDIT: Here's a better analysis:- Fish Oil and your Prostate. It looks as though n-6 was measured, which makes my analysis wrong, but I'm keeping the double face-palm, as the full study is hidden behind a £30 pay-wall. Here's another good analysis:- Omega-3 Fats and Cancer.

Completing the trine: Which are the safest fats?

First, watch this video by Chris Masterjohn.

Diets very high in pufas (polyunsaturates) are not beneficial to heart health or longevity. Flora? No thanks!

Here's a chart. The beige & grey bars represent pufas (omega-6 & omega-3).

Comparison of dietary fats

The yellow bars represent monounsaturates and the orangey-red bars represent saturates. I consider these to be harmless, as long as you don't go mad and eat them in such large amounts that you gain weight.

Bearing in mind the information in the video, plus the information in Fats: Spawn of Satan or Dogs' Doodads? , I use only fats from the bottom 6 for cooking (olive oil and butter, actually).

Flaxseed oil can be used as an omega-3 supplement for vegetarian/vegan women, as omega-3 pufas are as rare as rocking-horse poo in most foods (apart from oily fish).

Non-vegetarian/vegan people can get their long-chain omega-3 pufas (EPA & DHA) from oily fish. As vegetarian/vegan men barely produce any DHA from the omega-3 in flaxseed oil, they should get it from algal DHA supplements. See Extremely Limited Synthesis of Long Chain Polyunsaturates in Adults: Implications for their Dietary Essentiality and use as Supplements.

Inflammation: Is omega-6 really to blame?

Take a look at the following diagram from Tripping Lightly Down the Prostaglandin Pathways showing the omega-6 and omega-3 pathways.


Omega-6 pufas result in the production of Series 1 prostaglandins (anti-inflammatory) and Series 2 prostaglandins (inflammatory). Omega-3 pufas result in the production of Series 3 prostaglandins (anti-inflammatory).

Now, see Are diets high in omega-6 polyunsaturated fatty acids unhealthy?

"Insulin sensitivity might be the common factor relating disease to fatty acid metabolism — both within and between the fatty acid pathways. A high linoleate to arachidonate concentration occurs in insulin resistance, in diabetic complications and also in some tumours."

"Current epidemiological and clinical evidence supports the regular consumption of cold-water fish as part of a balanced diet, in which attention to lifestyle and the quantities eaten (to prevent obesity and the insulin resistance syndrome) may be more critical than the nature of the fatty acids consumed."

Do you see where I'm going with this? If you have insulin resistance, don't change your diet (low in carbs & avoiding omega-6) to suit the insulin resistance. Tackle the insulin resistance!

This isn't an open invitation to start guzzling high-pufa oils. Stick to oils that have been squeezed out of things that grow in hot climates. I include Extra-Virgin Olive Oil in this category. Check the label, as the pufa contents of different EVOOs vary. Solesta from Aldi contains only 6.6% pufas.

EDIT: In addition, your brain depends on omega-3 to function properly. Too much omega-6 can "fry" it. See Mental Health and Omega 3/6 Ratio, A New Review.

Vitamin D is anti-inflammatory. Fish oils are also anti-inflammatory.


I just spotted this on Anthony Colpo's Blog: The Adventures of Chris “Razzi” Razwell and Other Assorted Internet Psychos. Oh, my!


And finally: I made mum a CD of "Dare" by The Human League (I bought it in vinyl years ago) and played it on the CD/Record player in the lounge at the nursing home. She loved it and was moving her arms in time with the music. This is her favourite track from that album.

Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet

Thanks to Stephan Guyenet for bringing the study n-6 Fatty acid-specific and mixed polyunsaturate dietary interventions have different effects on CHD risk: a meta-analysis of randomised controlled trials to my attention in his post Diet-Heart Controlled Trials: a New Literature Review. This shows that diets high in omega-6 (n-6) polyunsaturates but low in omega-3 (n-3) polyunsaturates are heart-unhealthy.

In the West, we are advised to eat lots of "heart-healthy" sunflower oil & spreads. These contain about 70 times more omega-6 than omega-3. Safflower, Grapeseed, Corn & Groundnut Oils also have high omega-6:omega-3 ratios, according to Comparison of Dietary Fats Chart.

I then found the following study also on the British Journal of Nutrition:- Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet.

This shows that traditional hunter-gatherer diets have a short-chain omega-3:omega-6 ratio of 1·12–1·64 and a long-chain omega-3:omega-6 ratio of 0·84–1·92. In other words, there is a moderate balance between omega-6 and omega-3 polyunsaturates.

The diets are also relatively high in protein (25–29% energy) and fat (30–39% energy) but moderate in carbohydrate (39–40% energy).

I thought that followers of a Paleo-type diet would find this interesting.

EDIT: I've just noticed that O Primitivo has already posted about this study!

We are not all the same.

Cont'd from Everyone is Different.

Lyle (McDonald) brought the following study to my attention to illustrate that "We are not all the same":- Some Metabolic Changes Induced by Low Carbohydrate Diets. On a very-low-carb diet, one subject’s total cholesterol rose to 12.9mmol/L (500mg/dL in US units). The others didn't.
See also LDL cholesterol goes sky high on fatty diet.

I posted the study in various blogs to make the above point. Here are some of the replies I got:-
"Lyle? Lyle McDonald? Is that where you got that study, Nigel?" and... "I’m usually a pretty polite guy, Nigel. But based on this quote from the beginning of the study you mentioned, the people who wrote this study were a bunch of f**kwads, and really don’t deserve our attention. It’s a hatchet job."
"That was a weird study (1967) what I could make of it." and... "The men did all the stages but the women only did 3 stages of the diet."
"The fats were mostly omega-6 PUFA 13-35 grams worth..."
"The report you cite is so old and out of date that it makes me cry..."

My point was well & truly missed. I got the distinct impression that people thought I was criticising very-low-carb, high-fat diets. I wasn't. The simple fact is that there is no "One True Diet" that suits absolutely everybody. In the olden days everywhere & in poor countries nowadays, people that ate/eat the wrong diet for their body died/die young. Nowadays in rich countries, they get put on drugs e.g. oral hypoglycaemics (to lower blood glucose) & hypolipidaemics (to lower blood cholesterol/triglycerides).

Please note that omega-6 PUFAs tend to lower serum cholesterol rather than raise it, as per Fig. 2 of Types of Dietary Fat and Risk of Coronary Heart Disease: A Critical Review. However, don't rush off and eat shed-loads of omega-6 PUFA (e.g. corn oil) in the mistaken belief that it will make you live any longer. See (1971) Incidence of cancer in men on a diet high in polyunsaturated fat - Pearce.

Finally, for a little light relief, here is the latest result for Google Fight between "Healthy "low-fat diet"" and "Healthy "low-carb diet"". Oh, YES!

Cont'd on Everyone is Different, Part 2.

So, when & where did it all go wrong?

No, I'm not talking about Demand Five! I'm talking about us, modern man & woman. We have improved hygiene, clean water & food, modern medicine, anti-biotics, anti-virals etc. We should be enjoying good health and vitality into our nineties. We're not, though. Degenerative diseases like Type 2 Diabetes, Coronary Heart Disease, Cancer, Dementia, IBS etc are afflicting increasing numbers of people (including youngsters) and are even starting to reduce our longevity statistics. Why?

On one side of the fence are the anti-animal fat brigade who claim that animal fats are the cause of all our health problems and that we should all be eating more vegetable fats and reducing our cholesterol.

On the other side of the fence are the anti-carb brigade who claim that carbohydrates are the cause of all our health problems and that we should all be eating less carbohydrates and increasing our fat consumption.

I'm sure you can guess where I am. I have the splinters to prove it!

In 1911, hydrogenated vegetable oil (Crisco) entered the marketplace. So, in 1911, fat turned bad! See The rise and fall of Crisco.

Interestingly, rates of Coronary Heart Disease started to rise from 1920, 9 years later. Co-incidence?

Our genes may have not changed much in the last few hundred thousand years, but our lifestyles certainly have. We now live mostly sedentary lives (which makes our muscles less sensitive to insulin). We now live and work mostly indoors (which makes us deficient in Vitamin D).

We now don't eat much oily fish. Our vegetables contain much less omega-3 fat than they used to (to make them stay fresh for longer). Our meat now contains much more omega-6 and much less omega-3 fat than it used to (due to feeding animals on grains). These changes make us deficient in omega-3 fat (which makes our muscles less sensitive to insulin).

We now eat loads of refined carbohydrate (which causes unstable blood glucose & insulin levels) and loads of processed foods (which makes us deficient in Magnesium and fibre/fiber).

As a result of all of the above changes, we have many modern diseases. We can't blame it on one factor only. So, what can we do? Here's one suggestion....



























Good health!

I've got a lovely bunch of coconuts!

Coconut Oil is the No. 1 most stable oil for cooking at high temperatures.

What’s in coconut oil?

According to http://www.manitobaharvest.com/nutrition/index.asp?itemID=183 , coconut oil is ~91% saturated fatty acids, ~7% monounsaturated fatty acids, ~2% omega-6 fatty acids and zero omega-3 fatty acids.

According to McCance and Widdowson's “The Composition of Foods”, the fatty acid composition of coconut oil is as follows:-

Name(:0=sat, :1=mono, :2=poly, n6=omega-6) Quantity (%)
Caprylic Acid (C8:0)___________________________7.5
Capric Acid (C10:0)____________________________7.1
Lauric Acid (C12:0)___________________________47.7
Myristic Acid (C14:0)_________________________15.8
Palmitic Acid (C16:0)__________________________9.0
Stearic Acid (C18:0)___________________________2.4
Arachidic Acid (C20:0)_________________________1.0
Palmitoleic Acid (C16:1)_______________________0.4
Oleic Acid (C18:1)_____________________________6.6
Linoleic Acid (C18:2 n6)_______________________1.8

Won’t all that saturated fat give me a heart attack?

Whether or not you get coronary heart disease depends on your whole diet. According to http://www.ajcn.org/cgi/reprint/34/8/1552.pdf , Pukapukans got 26% (male) to 30% (female) of their total Calories from saturated fats. Tokelauans got 47% (male) to 49% (female) of their total Calories from saturated fats. Tokelauans had total serum cholesterol 35-40mg/dL (0.9- 1.03mmol/L) higher than Pukapukans.

As Tokelauans were getting about seven times more energy from saturated fats than the 7% that current healthy eating guidelines recommend, they must have been dropping like flies from coronary heart disease or strokes, right? Wrong! To quote:-
“Vascular disease is uncommon is both populations and there is no evidence of the high saturated fat intake having a harmful effect in these populations.”
How come? Well, if you look at the rest of the Tokelauans’ diet, you’ll see virtually no refined sugar or cereal products. Basically, they weren’t eating any junk. When Tokelauans migrated to New Zealand, their sat fat intake fell to ~41% of total calories but as they were eating more refined carbs & sugar, their lipid profile got worse.

What are the benefits of coconut oil?

Medium-chain fatty acids are metabolised rapidly without passing through the liver and they provide a quick source of energy for muscles. There is some evidence that medium-chain fatty acids stimulate the thyroid gland to secrete more T4 & T3 which can be an aid when cutting. There is also some evidence that Lauric Acid has anti-bacterial & anti-viral properties. Coconut oil is also good for the skin when rubbed in.

Where can I buy coconut oil?

Don’t buy cheap coconut oil. It’s almost certainly Refined, Bleached & Deodorised which detracts from its health benefits. The best coconut oils are Organic Virgin Oils. Some good on-line sources are
http://www.fresh-coconut.com/ ,
Coconut Oil UK and
http://www.revital.co.uk/product_search.cfm?searchString="Nutiva+Organic+Extra+Virgin+Coconut+Oil"

In addition, check-out Rosso's Blog on Saturated oils.

As sure as Eggs is Eggs.....

...is grammatically incorrect! Rumour has it that it's a corruption of "As sure as x = x". But anyway....

Eggs are very nutritious and should be eaten freely as part of a healthy diet.

Click http://www.nutritiondata.com/facts/dairy-and-egg-products/111/2 and set the serving size to 1 large (50g) to see what nutrients there are in a raw whole egg.

Click http://www.nutritiondata.com/facts/dairy-and-egg-products/112/2 and set the serving size to 1 large (33g) to see what nutrients there are in a raw egg white.

Click http://www.nutritiondata.com/facts/dairy-and-egg-products/113/2 and set serving size to 1 large (17g) to see what nutrients there are in a raw egg yolk.

The amino acid scores for whole egg , white and yolk are 136, 145 and 146 respectively. Eggs are a good source of complete proteins. This is because the yolk and white need to contain everything necessary for a growing chick embryo.


Can I drink eggs raw to save time?There are three potential problems with this:

1) Salmonella poisoning. Unless you’re pretty sure of the hens that the eggs came from, there is a risk of poisoning from raw eggs. This doesn’t apply to pasteurised eggs from suppliers like http://www.eggnation.co.uk/ for example.

2) Poor absorption of egg white protein. According to http://jn.nutrition.org/cgi/content/full/128/10/1716 , only 51% of raw egg white protein is absorbed during digestion compared to 91% for cooked egg white protein. According to http://ajpgi.physiology.org/cgi/content/full/277/5/G935 , the figures are 65% and 94% respectively. The second study used 200g of white and one yolk. I don’t believe that there is a problem with the absorption of raw egg yolk, though problem 1 still remains. Pasteurised egg white protein is well absorbed.

3) Poor biotin absorption. Raw egg white contains a glycoprotein called avidin which binds to biotin (Vit. B7) in the yolk and prevents its absorption. Cooking or pasteurisation denatures (changes the 3-D structure of) the avidin and renders it harmless.


What about all that cholesterol in egg yolks?

Current “Healthy Eating” guidelines state that we should eat no more than 3 egg yolks/whole eggs per week. This is based on the erroneous assumption that dietary cholesterol always increases serum cholesterol and that this is always a bad thing. According to http://www.ajcn.org/cgi/reprint/32/5/1051.pdf , adding or not adding 500mg of dietary cholesterol from two large eggs per day made no significant difference to serum cholesterol or triglycerides in 116 healthy male subjects. Some went up and some went down. Eddie Vos at http://www.health-heart.org/cholesterol.htm reckons that you’d have to eat 20 whole eggs per day to get as much dietary cholesterol as the liver produces each day (5g). Egg yolks do contain some fat and this should be factored into your total diet. If you happen to have the genes for familial hypercholesterolaemia, then you need to keep a close eye on dietary cholesterol intake. See also Eat Whole Eggs All Day and Throw Your Statins Away? 375x Increased Dietary Cholesterol Intake From Eggs Reduces Visceral Fat & Promotes Healthy Cholesterol Metabolism.

There is a problem with modern eggs though, and it’s caused by the food that’s fed to the hens. Grains contain about 50 times more Linoleic acid (omega-6) than Alpha-Linolenic acid (omega-3) and this raises the omega-6:omega-3 ratio of the eggs that the hens lay. Hens eating a natural diet of bugs, grubs and vegetation lay eggs with a 1:1 ratio of omega-6:omega-3, but grain-fed hens lay eggs with an omega-6:omega-3 ratio of >10:1. A high omega-6:omega-3 ratio in the diet is associated with increased risk factors for heart disease, cancer and Insulin Resistance (pre-type 2 diabetes). Therefore, if large numbers of cheapo eggs are eaten, it’s advisable to eat other foods that are rich in omega-3 fats.

Vegetarians & vegans, listen up!

Firstly, by vegetarian I mean someone who does not eat the flesh of animals. This includes fish and chicken.

Dr. Michael Greger M.D. ("The Vegan MD") has a very informative and witty lecture Optimum Vegetarian Nutrition: Surprising New Research on Omega 3's and B12.

In a nutshell, vegetarians & vegans don't live any longer than omnivores – as shown in a study of 28,000 subjects. Vegetarians & vegans have the same rates of coronary heart disease as omnivores but double the rates of Alzheimer's Disease. WHY? There are two reasons.

1) Vegetarians and vegans don't eat oily fish and most don't eat cracked or ground-up linseeds either. This means that the ratio of omega-6 to omega-3 fats in their diet is way too high. This increases the risk of diabetes, certain cancers and heart disease.

2) Only animal produce naturally contains Vitamin B12. Lack of B12 in the diet raises the level of homocysteine in the blood, which attacks artery walls. This raises the risk of heart disease and Alzheimer's Disease. What to do?

1) Eat 25g (women) or 50g (men) of powdered brown or golden linseeds per day or add 10g (women) or 20g (men) of flax-seed oil to food per day or take 10 (women) or 20 (men) 1000mg flax-seed oil capsules per day. Or supplement with ~1000mg/day vegan DHA.

2) Eat foods fortified with vegan B12 or supplement with vegan B12.

'Nuff said?

I was just thinking......

On a messageboard in a galaxy far far away, someone suggested that as many as one in three people in the UK could have impaired carbohydrate metabolism. This set me thinking.

London is 51degrees North of the Equator, so the sun has to pass through ~45% more atmosphere to reach us, compared to the Equator.

According to Elina Hyppönen & Chris Power, (edited) "The prevalence of hypovitaminosis D was highest during the winter and spring, when 25(OH)D concentrations less than 75nmol/L were found in 87.1% of participants, respectively; the proportion was 60.9%, respectively, during the summer and autumn."

Note that 75nmol/L was insufficient to give me normal Insulin Sensitivity. See Chiu, Chu, Go & Saad. However, greater than 160nmol/L was sufficient, but that was only obtained after I supplemented with 5,000iu/day of Vitamin D3 (25 x RDA).

A deficiency of omega-3 EFAs can cause Insulin Resistance (poor Insulin Sensitivity). See Ghafoorunissa, Ahamed Ibrahim, Laxmi Rajkumar & Vani Acharya, Storlien LH, Kraegen EW, Chisholm DJ, Ford GL, Bruce DG & Pascoe WS and Yam D, Bott-Kanner G, Friedman J, Genin I, Klainman E & Shinitzky M.The typical omega-6:omega-3 ratio in the British diet is ~15:1. This is partly due to the fact that animal produce from grain-fed animals contains a lot more omega-6 and a lot less omega-3 than it used to. See Is food less nutritious than it used to be? Andre Purvis investigates. In addition, people eat grains, nuts, seeds, oils & spreads high in omega-6 and don't eat much oily fish, powdered Flax-seeds (a.k.a. Linseeds) or Purslane (a plant that's relatively high in omega-3).

With all of these problems, I wonder what percentage of the UK population actually do have some degree of impaired carbohydrate metabolism? It might be more than one in three.

According to The eatwell plate, one third of our total Calories are supposed to come from bread, rice, potatoes, pasta and other starchy foods. All of these foods raise blood glucose. Impaired carbohydrate metabolism makes for roller-coaster blood glucose levels which encourages over-eating, leading to obesity (see my Blog post on Blood Glucose, Insulin & Diabetes.)

I think that that's enough thinking for now.

How to lose body-fat healthily.

Previous blog posts have been about Carbohydrates, Fats & Proteins. However, when you go shopping, you buy food. So this blog post is going to be about food. Updated!

1) If you're eating a high-carb diet, eat 6 small meals or 3 meals and 3 snacks per day to keep your blood glucose relatively stable. I used to believe that it also kept your metabolic rate high, but I now know this to be a myth. If you're the type of person who gets lowish blood glucose in the mornings (which may make you ravenously hungry and therefore highly likely to buy junk food when you're away from home), skipping breakfast is not advisable. If you're the type of person who isn't satisfied by small meals/snacks, a small number of large meals (Intermittent Fasting) is a better option.

2) Meals and snacks should contain proteins, fats and fibrous carbs.

3) Slow sugary/starchy carbs can be eaten in meals/snacks at breakfast and before/after workouts/exercise/intense activity. If/when you are sedentary, keep slow sugary/starchy carbs to a minimum. Keep fast sugary/starchy carbs to a minimum (except for the occasional treat or post-workout) as they can cause large fluctuations in blood glucose and insulin levels. The more intense exercise you do, the more slow sugary/starchy carbs you can eat.

4) Drink >1.5 litres of no-added-sugar watery drinks per day. If your urine is darker than straw, drink more. If you're weeing too often, drink less.

5) Balance your omega-6 and omega-3 essential fatty acids (EFAs) by eating about 100g of omega-3 rich oily fish (sild, sardines, pilchards, mackerel, herring, salmon, trout, fresh tuna etc) per day or supplement with fish oil capsules such that you get at least 2g of EPA+DHA per day. Please note that tinned tuna contains virtually zero omega-3 fat.
If you're vegetarian or vegan, eat 25g (women) or 50g ( men) of powdered linseeds (a.k.a. flaxseeds) per day with lots of fluids or supplement with flaxseed oil in bottles/capsules such that you get at least 10g (women) or 20g (men) of flaxseed oil per day.

6) Eat 2 to 3 portions of low-sugar fruits per day - preferably before meals/snacks. Minimise your consumption of high-sugar fruits.

Proteins are:- Meats, poultry, fish, eggs, cheese, Quorn, seeds, nuts, legumes (peas, beans & lentils).

Fibrous carbs are:- All vegetables that grow above ground level, bulbs (onions, leeks, garlic etc) and "vegetable" fruits (tomatoes, peppers, cucumbers/courgettes, aubergines, avocados, olives etc).

Slow sugary/starchy carbs are:- All-bran, no-added-sugar muesli, oats, sweet potatoes, lightly-boiled new potatoes eaten hot, cold or refrigerated, Basmati rice, non-overcooked legumes & root veggies, lumpy wholegrain rye breads, Burgen/Vogel's soya & linseed breads.

Fast sugary/starchy carbs are:- White wheat breads, wholemeal wheat breads, most breakfast cereals including Shredded Wheat, Weetabix, Cheerios, Grapenuts etc, sugar, sweets, chocolate, cakes, biscuits, cereal bars, sweetcorn, overcooked tubers e.g. jacket potatoes, overcooked root veggies, overcooked legumes e.g. baked beans.

High sugar fruits are:- Ripe & over-ripe bananas, grapes, pineapples, sweet apples, sweet pears, sultanas, raisins, currants and any dried fruits with added sugar.

Low sugar fruits are:- Berries, stone fruits, citrus, Granny Smith apples, Conference pears. Dried apple rings, apricots, pear halves, peach halves and prunes without added sugar are high in sugar but they release that sugar very slowly.

Fats are sats, monos and the EFAs mentioned above. Butter is high in sats and monos. Olive oil & spreads are high in monos. Sunflower/safflower/corn oils & spreads are very high in omega-6 EFAs - minimise your consumption of these. Don't fry or roast with high-EFA oils as they oxidise and convert into trans-fats too quickly. Meats contain sats, monos and some EFAs. Minimise your consumption of anything with the word "hydrogenated" in the ingredients list.

Some foods fall in-between categories like yellow bananas which are medium speed sugary/starchy carbs. Green bananas are slow carbs and black bananas are fast carbs.

Depending on your insulin sensitivity, speed of metabolism and exercise levels, you may get away with eating fast sugary/starchy carbs - you'll just have to "suck it and see".

One final bijou tip-ette:- Avoid walking down "dodgy" supermarket aisles (confectionery, cereals, booze, fizzy drinks) as "What the eye don't see, the heart don't grieve over".

Happy New Year folks!

Cont'd on How to lose body-fat healthily, Part 2.

Fats: Spawn of Satan or Dogs' Doodads?

Fats get a lot of bad press in the media. There are so many adverts with "X% fat-free" or "only 1g of fat per Jaffa Cake" as if that's going to stop you from getting fat when you "om nom nom" your way through a whole box of the things!

Saturated fats are usually described as "bad" and polyunsaturates are usually described as "good". This is simplistic. Everything is bad in excess, even polyunsaturates. The thing about fats is that there are four basic types (saturates, monounsaturates, omega-6 polyunsaturates and omega-3 polyunsaturates) and they need to be consumed in roughly the right proportions for optimum health. Suffice it to say, the majority of people in the West do not eat them in anywhere near the right proportions. So, what exactly are fats?

Fats

Fats are an ester of glycerol and three fatty acids and are also known as triglycerides or triacylglycerols.

1 molecule of glycerol + 3 molecules of fatty acid = 1 molecule of triglyceride + 3 molecules of water.

It's the fatty acids that determine whether a fat is sat, mono etc. The four different types of fatty acid all have a CH3 at one end and a COOH at the other. The difference is in the middle section.

Saturated fatty acids have a middle section consisting of all CH2's. Here's a diagram for Stearic acid (the predominant fatty acid in beef):-

__H H H H H H H H H H H H H H H H H OH-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-O-H__H H H H H H H H H H H H H H H H HMonounsaturated fatty acids have one C=C bond in the middle, which is usually (but not always) 9 from the left-hand end resulting in monounsaturates usually being referred to as omega-9's, as omega is the letter at the end of the Greek alphabet. Here's a diagram for Oleic acid (the predominant fatty acid in olive oil):-

__H H H H H H H H_____H H H H H H H OH-C-C-C-C-C-C-C-C-C=C-C-C-C-C-C-C-C-C-O-H__H H H H H H H H H H H H H H H H H

Omega-6 polyunsaturated fatty acids have two or more C=C bonds in the middle with the last one always being 6 from the left-hand end. Here's a diagram for Linoleic acid (the predominant fatty acid in sunflower oil):-

__H H H H H_____H_____H H H H H H H OH-C-C-C-C-C-C=C-C-C=C-C-C-C-C-C-C-C-C-O-H
__H H H H H H H H H H H H H H H H H

Omega-3 polyunsaturated fatty acids have three or more C=C bonds in the middle with the last one always being 3 from the left-hand end. Here's a diagram for Alpha-linolenic acid (the predominant fatty acid in flax-seed oil):-

__H H_____H_____H_____H H H H H H H OH-C-C-C=C-C-C=C-C-C=C-C-C-C-C-C-C-C-C-O-H__H H H H H H H H H H H H H H H H H

These diagrams are slightly misleading. Where there is a C=C bond, there are two H's on the "underside" only of the molecule. This asymmetry causes the H's to repel each other and bend the molecule into a V-shape at each C=C bond. C=C bonds with H's on the same side are known as "cis" bonds. The above molecule is really cis, cis, cis (c,c,c) Alpha-linolenic acid. The other type of C=C bond is known as "trans" and looks like the following diagram:-

__H H H___H H___H H___H H H H H H H OH-C-C-C=C-C-C=C-C-C=C-C-C-C-C-C-C-C-C-O-H
__H H___H H___H H___H H H H H H H H

This is a diagram of trans, trans, trans (t,t,t) Alpha-linolenic acid. As the H's are on opposite sides of the molecule, they do not repel each other and the molecule is straight as shown above. Note that saturated fatty acid molecules are naturally straight. Therein lies the problem with trans-fatty acids. They're straight, like saturated fatty acids but have unsaturated bonds which are prone to oxidation. See http://www.cyberlipid.org/perox/oxid0002.htm WARNING! Heavy-duty organic chemistry!

Our bodies take trans-fatty acids and incorporate them into cell membranes as if they were saturated fatty acids. This results in atherogenicity (artery-clogging), damage to the immune system and other health problems. Trans-fatty acids are found in partially-hydrogenated vegetable oils and so any processed foods or cooking/spreading fats which has the word "hydrogenated" high-up in the ingredients list should be avoided. These truly are bad fats. There are also naturally-occurring trans-fatty acids made by bacteria in the stomachs of ruminant animals, like Conjugated Linoleic Acid (CLA). This looks a bit like the diagram below:-

__H H H H H_____H___H H H H H H H H O
H-C-C-C-C-C-C=C-C=C-C-C-C-C-C-C-C-C-C-O-H
__H H H H H H H___H H H H H H H H H

This has one of the C=C bonds shifted to the left and also has one cis bond and one trans bond, so the molecule is always bent. CLA has possibly beneficial properties but medical studies show mixed results. It's certainly not artery-clogging, so don't let anyone put you off eating butter from grass-fed cows (e.g. New Zealand butter) by saying that it has trans-fats in it. CLA is a harmless trans-fat.

Anyway, back to diet. Saturated fat consumption should be about 10% of total calories. This is because, even though sat fats are not essential (our bodies can manufacture them), this guarantees adequate levels of sex hormones in the body. Total polyunsaturate consumption should be about 5% of total calories, with a ratio of omega-6 (O6) to omega-3 (O3) of between 1:2 and 4:1. As O3's are only found in greater quantities than O6's in flax-seeds (a.k.a. linseeds) and oily fish, and many people eat way too little or no oily fish (and who, other than body-builders and some vegetarians/vegans, eats flax-seeds?), the O6:O3 ratio in the West is about 20:1. This is due to the widespread consumption of meats, eggs & milk from grain-fed animals, grains, nuts and seeds. So, it’s not surprising that there are high rates of heart disease and other inflammatory diseases in the West, as O6's end up in series 1 & 2 prostaglandins and series 2 prostaglandins are pro-inflammatory. O3 fats end up in series 3 prostaglandins, which are anti-inflammatory.

So eat up yer oily fish if you're not vegetarian or vegan. Otherwise, eat up yer ground-up flax-seeds!

Monounsaturates can make up 15% to 35% of total calories, depending on activity levels. Remember from the histogram in the Blog post Everyone is Different, sedentary people on average burn twice as much energy from fats as from carbs. So, if energy from protein is 25% say, 25% of energy can come from carbs and 50% can come from fats i.e. a 2:1 ratio of fats:carbs. The cyclists at the left-hand end of the histogram in Chapter 1 would do best on 25% protein, 5% carbs, 70% fat when sedentary, whereas the cyclist at the right-hand end of the histogram would do best on 25% protein, 60% carbs, 15% fat when sedentary. When active, more carbs are needed by everyone.

Which fats contain which fatty acids? See http://homepage.ntlworld.com/nigel.kinbrum/comparison-of-fats.gif for a Comparison of Dietary Fats chart. Click http://www.apag.org/oleo/fatsoils.pdf for tables of Properties & Composition of Vegetable & Special Oils and Properties & Composition of Animal & Marine Fats & Oils.

For high-temperature cooking, saturates are the least likely to oxidise (when they're on fire, they're oxidising!), followed by monos, then omega-6's with omega-3's being the least stable. An oil doesn't have to be smoking to be oxidising. Alpha-linolenic acid oxidises at room temperature, which is why linseed oil is used to varnish cricket bats and soften putty. The best non-animal fat for high-temperature cooking is Coconut Oil, followed by Palm Oil and then Olive Oil. Extra-Virgin Olive Oil (EVOO) has a lower smoking temperature than refined Olive Oil (due to higher levels of free fatty acids), but has higher levels of polyphenol antioxidants, which makes it pretty heart-healthy.

Oils high in polyunsaturates shouldn't be heated above 100°C, as polyunsaturates can change from the cis configuration to the trans configuration at temperatures as low as 102°C. See http://www.harricksci.com/sites/default/files/pdf/application_notes/FatIR_App-Notes_ATR_Oil-Analysis.pdf