Our hunter-gatherer ancestors consumed a diet very different from what’s typical today.
Grains were introduced into the diet after the appearance of stone tools. Refined grains were available after the invention of automated rolling and sifting devices.
Milk, cheese and other milk products were introduced with the domestication of livestock.
Salt consumption rose when technology to mine, process, and transport it became available.
Meat consumption increased with animal husbandry. It further increased with the advent of technology that enabled grains to be efficiently fed to cattle, which allowed cattle to be fattened quickly.
Sugar consumption has risen since the beginning of the Industrial Revolution.
Grains, fish, meat, poultry, shellfish, cheese, milk, and salt all produce acid, so the introduction and dramatic rise in our consumption of these foods meant that the typical Western diet became more acid-producing.
Some practitioners recommend the alkaline diet if a person has the following symptoms and other illnesses have been ruled out.
Lack of energy
Excessive mucous production
Frequent colds and flu
Anxiety, nervousness, irritability
Ovarian cysts, polycystic ovaries, benign breast cysts
There’s actually a lot of controversy about the alkaline diet. Some smart people think it is complete BS. Skeptics actually run the wikipedia page on the alkaline diet and link to fellow skeptics. They simply believe the body can adjust to the radical change in foods consumed with no problem. These people also tend to be advocates of bean and dairy consumption. They claim that blood ph is unaffected, but that’s not the point. The point of the diet is that a more alkaline diet leads to more calcium retention and less fat accumulation.
There are studies like this one that see no association between bone mineral density and acid load (although even that one saw a correlation in older men). In this case the study looked at an older study and made estimates of net asset load and renal acid load - which I assume were based on the dietary data available - and then compared that to bone mineral density. So that’s certainly a reason t be skeptical. It’s possible that bone mineral density is more correlated with things like exercise and physical size.
Actually if you’re overweight, your bone mineral density actually increases.
it was noted that overweight (BMI > 25 < 29.9) was neutral or protective for BMD
So it’s very possible that those on poor diets simply got fatter, which put more stress on their bones, which led to them having more dense bones.
So what other ways can this data be looked at?
There is evidence that having an alkaline diet increases calcium absorption. Here’s a link to a cool study where they basically fed people alkaline chemicals. As it says, calcium retention went up.
The effects of neutralization of dietary acid load (equimolar amounts of NaHCO3 and KHCO3 substituted for NaCl and KCl) in nine healthy subjects (6 men, 3 women) under metabolic balance conditions on calcium balance, bone markers, and endocrine systems relevant to bone [glucocorticoid secretion, IGF-1, parathyroid hormone (PTH)/1,25(OH)2 vitamin D and thyroid hormones] were studied. Neutralization for 7 days induced a significant cumulative calcium retention (10.7 ± 0.4 mmol) and significantly reduced the urinary excretion of deoxypyridinoline, pyridinoline, andn-telopeptide. Mean daily plasma cortisol decreased from 264 ± 45 to 232 ± 43 nmol/l (P = 0.032), and urinary excretion of tetrahydrocortisol (THF) decreased from 2,410 ± 210 to 2,098 ± 190 μg/24 h (P = 0.027). No significant effect was found on free IGF-1, PTH/1,25(OH)2 vitamin D, or thyroid hormones.
In a recent study estimating the net acid load (NEAP) of 159 hypothetical pre-agricultural diets, 87 % were found to be base producing, with an estimated mean NEAP of negative 88 mEq/d. In comparison, calculations from the US Third National Health and Nutrition Examination Survey (NHANES III) found the average American diet to be acid producing, with an NEAP of positive 48 mEq/d.
Diet net acid load can be estimated from measurements of urinary excretion of ammonium, titratable acids and bicarbonate (called net acid excretion; NAE), or can be calculated from dietary constituents (called net endogenous acid production; NEAP).
In vivo studies have generally supported the in vitro ﬁndings that acid-promoting diets are associated with both increased Ca and increased bone matrix protein excretion (used as a marker for estimating bone loss), and that neutralising the acid intake with diet or bicarbonate supplements decreases urine Ca and bone matrix protein excretion (18 – 21) . In a trial of 170 postmenopausal women, for example, potassium bicarbonate supplementation reduced daily urinary Ca excretion, and one could predict which women would beneﬁt most – those with the greatest urinary Ca loss
In an examination of over 1000 women between the ages of 45 and 54 years, a lower dietary intake of acid-producing foods correlated with greater spine and hip bone mineral density, as well as greater forearm bone mass, after adjusting for age, weight, height and menstrual status (60) . In the Study of Osteoporotic Fractures Research cohort, over 1000 women aged 65 þ years were enrolled in a prospective cohort study.
A number of trials have shown that the bone loss can be reversed by the addition of a base…Potassium citrate combined with calcium citrate may be more beneﬁcial than either alone, as demonstrated in a cross-over trial on bone turnover in postmenopausal women. Urinary Ca excretion and markers of bone health were improved with potassium citrate, more so in those consuming a high-Na diet. … A recent study suggests that bicarbonate has favourable effects on bone resorption and Ca excretion
Kidney stones… In a study of nearly 200 renal stone-formers designed to identify the greatest risk factors for nephrolithiasis[kidney stones], it was the potential acid load of the diet which had the strongest association with stone risk…Potassiummagnesium citrate has been shown to counter renal stone formation associated with immobilisation and was associated with a signiﬁcant increase in urinary pH.
I view all this as additional evidence that a diet consisting of fruits and vegetables with some fish is healthy, and that foods like dairy and grains are not the best health choices.