What can we learn for breast milk? Part 2: Micronutrients

All these calculations use 84 grams of protein worth of breast milk, to normalise it to the minimum needed for an adult (see part 1).

I'm also aware that the nutritional content of breast milk varies depending on the mother's diet but using the USDA data for it means we get a nice average of an American (which I'm aware may not be the best nutritionally).


Here's my CRONometer print out for the breast milk at 84g of protein (ignore chromium, there's just no data for it):

Vitamins

Let's start with vitamin A, this amount of breast milk provides ~16.5kIU vitamin A which is quite a bit and more than what I or the WAPF recommend (10kIU). Infants are growing rapidly and so need more vitamin A though, so this is fine.

With the B vitamins everything is in normal meaty amounts, except the B2 is slightly higher and B5 is a lot higher. B5 is needed for forming acteyl-coA so may be high due to the infant's high energy requirement, it's also used in the synthesis of fatty acids and cholesterol so again good reasons for it to be high. B6 is also fairly low, but the milk provides huge amounts of folate and choline instead so homocysteine levels will be fine. The WAPF comments that most mothers are also deficiency in B6 due to low meat consumption  The amount of choline is so incredibly high due (9 large eggs worth) to its other use for helping the developing brain. As previously discussed the amount of choline/folate/B6 needed are all interrelated.

Vitamin C is higher than would be gotten eating a carnivorous diet, but the protein needs for infants is very high and so little is left over to make uric acid, so breast milk supplies ascorbic acid instead.

Vitamin D is fairly low but almost all mothers are deficient in this vitamin. It's one of two supplements I recommend to everyone (the other being magnesium as soils are depleted), and should be supplemented based on your blood levels rather than a set IU amount.

The vitamin K is K1, as the USDA doesn't measure K2. It's quite low compared to the RDA and about twice the amount in 2000 calories worth of grain-fed rib-eye (grass-fed meat would have more K1 though), but as previously discussed K2 can do clotting like K1 so this is no problem.

Minerals

As previously discussed in my post about calcium, breast milk in the amount an infant drinks (rather than 84g of protein worth) only provides ~320mg calcium a day and this should be fine for an adult too.

Magnesium is lower than the RDA but still about double provided by just meat. Again I'll note that most mothers are deficient in magnesium due to the soil being depleted and that's why I recommend supplementing it.

Phosphorus is at about half the level of calcium which is why I originally recommended a 2:1 calcium:phosphorus ratio but further research shows our calcium needs are lower. The total amount is similar to that found in 2000 calories of rib-eye so I'm happy that this amount is ideal for an adult.

The level of potassium is almost at the USDA RDA which is interesting and may warrant the use of more potassium in a carnivore diet. But the ideal potassium:sodium depends on whether you're in ketosis or not, with ketosis meaning more sodium is needed per potassium. Infants, as far as I'm aware are not in ketosis due to the lactose in breast milk and so have more potassium and less sodium (or at least only mild ketosis). Additionally the level of sodium in breast milk is quite low as infant's kidneys struggle somewhat with sodium initially and slowly improve as the infant grows. This means that an adult in ketosis needs much more sodium and less potassium.

With selenium, the level is almost three times the RDA, but similar to the amount recommended by most for proper thyroid health (200ug), again American mothers are likely to be slightly deficient in this so 150-200ug is properly the best amount.

The manganese is quite high in breast milk, and is needed for mitochondrial functioning so may be high due to an infant's high energy requirements.

The iron in breast milk is very low, as it is in all mammal milks, as iron interes with zinc absorption and zinc is needed for the developing brain. Infants have large iron stores when born (or at least they should do if the placenta is allowed to return the infant's blood back to its body after birth and not clamped early like is usually done in the developed world; as much as half an infant's total blood can be lost to the placenta with early cord clamping, which is a huge amount!) so little is needed in the diet until at least 6 months old (older if delayed clamping) and the first weaning foods should be high in iron such as meat or liver.

The copper in breast milk is actually pretty low, only ~0.6mg total a day (rather than per 84g protein) and an infant will slowly run down the coper stored developed before birth similar to what it does for iron, again meaning the best weaning food would be liver (from beef or lamb, not pork) as it's rich in copper too. This means that our copper requirement is more than ~0.6mg per day, and as discussed in the phytic acid nutrients post I recommend 1-2.4mg of copper a day.

Conclusion

We can see that looking at the vitamins and minerals of breast milk, again in the context of the body it's designed to nourish, gives is good insight into the nutrition of an adult. I points to us needing more retinol, calcium, magnesium, potassium, sodium, selenium, and copper than is normally achieved just eating fatty meat. This points to the need include a few other choice animal foods in our diets for optimal health.

What can we learn from breast milk? Part 1: Macronutrients

Warning: post contains maths!

Breast milk is 1% protein, 6.9% carbohydrate and 4.4% fat by weight, or 5.6% protein, 38.8% carbohydrate and 55.6% fat by calories. It is low in protein and high in both fat and carbohydrates... Or is it?

Protein

Due to babies huge energy requirements*, they actually get ~0.89 grams of protein per pound body weight**, but this is more than an adult needs as the infant is growing rapidly so this amount can be seen as the maximum we would need (especially considering formulas made with higher protein levels are toxic to infants). This translates as 150lb adult needing a maximum of ~134 grams of protein a day, and at 2000 calories a day, this is 27% of calories.

* An infant weighing 5kg/11lbs needs 700 calories; this is ~64 calories per pound. A 150lb adult may need 2000 calories, or ~13 calories per pound. The infant’s energy requirements are almost five times that of an adult’s on a per weight basis.

**700 calories @ 5.6% protein = 39.2 calories from protein = 9.8g protein / 11lbs = 0.89 protein/lbs.

How little protein do we need though if that's the maximum? Well many keto dieters eat as little as 60g of protein a day fine (~12% @ 2000 calories), but this is usually done in fear of slightly higher fasting blood glucose levels on a ketogenic/low-carb diet even though such a thing is perfectly natural and safe. They're eating the absolute minimum they can get away with, which I think is a poor strategy. The body has an efficient system for getting rid of excess protein, via urea and uric acid. As previously discussed uric acid is a potent antioxidant and why I think we don't get scurvy on all meat diets, so protein in excess of our pure tissue requirement can be seen as a good thing!

Phinney/Volek in The Art And Science of Low Carb Living/Performance generally recommend 1.5g/kg protein (~0.68g/lb), this is ~102g at150lbs (~20% @ 2000 calories). Other recommendations include 0.7+g/lb of lean mass (84g/150lbs@20%bf, 17% @ 2000 calories), this seems much more reasonable minimum. Basing your protein needs off lean mass rather than whole mass is much smarter, as fat tissue doesn't increase protein requirements but muscle mass does. 102g of protein is almost exactly half way between 84g and 134g, so is a good middle ground target of protein intake.

Carbohydrates

The brain is the biggest user of carbohydrates in the body; in infants, it uses 50% of the body’s total energy requirements, but by adulthood only uses up 20%. This means the adult brain uses 40% of the energy required by an infant brain: this works out to ~15% of calories from carbohydrates (38.8% x 40% = 15.5%).

BUT... the carbohydrate source is lactose, made of glucose and galactose. Now galactose is very special, it's not used as an energy fuel like glucose, it's used for myelin synthesis (that is making nerve insulation), this is why human breast milk is so high in lactose, for the galactose! So that ~15% becomes ~7% of calories coming from carbs for an adult (~38g @ 2000 calories).

BUT... we can make glucose from protein (via gluconeogenesis) and glycerol from fats. Gluconeogenesis is constant regardless of diet, as we've discussed before, but as far as I'm aware there is no cap on glycerol->glucose synthesis. Estimates are at about 10% of whole fat can be converted to glucose from the glycerol.

The actual dietary requirement for carbohydrates is zero, and even infants do very well on ketogenic diets; we can synthesis all the glucose we need (which is less while in ketosis) from GNG and glycerol. The main reason for muscle wastage in starvation is it's being used for GNG (which is constant even in starvation), this supplies the glucose requirement easily and blood glucose levels remain steady right up until you die.

Fat

The rest of the body’s calories come from fat, which in an adult eating ~27% protein and ~7% carbohydrates is ~66%, or ~147 grams of fat on a 2000-calorie diet. This would be the minimum fat, as this is the maximum protein and carbohydrates we need. Taking in our minimum 84g protein and no carbs would mean we need to eat 83% of our calories as fat or ~184 grams of fat on a 2000-calorie diet.

Summary

So understanding the macronutrient ratios of breast milk in context of the body it is designed for gives up a good idea of what ratios are healthy for an adult human. This works out to ~17-27% protein, ~0-7% carbohydrates, ~66-83% fat, or 84-137g protein, 0-38g carbs, and 147-184g fat on a 2000-calorie diet. Such a diet would almost always be ketogenic (very metabolically damaged people may not handle even 38g carbs).

As calorie expenditure increases, say due to increased exercise, the extra calorie should come from fat, little extra protein or carbs are needed. During very heavy exercise some non-insulin-stimulating carb source may be used to aid recovery such as super starch, palatinose, or possibly pure fructose in order to refill glycogen stores (as discussed previously our ability to refill glycogen is limited by GNG and is less than that of other carnivores).